WO1991011325A1 - Conductive polymer blends and methods for making the same - Google Patents

Abstract

Shaped articles such as fibers, films, tapes, rods and the like are fabricated from composites of nonconducting, flexible chain carrier polymers and conjugated polymers. The shaped, composite articles are electrically conductive and also display excellent mechanical properties, i.e., with respect to tensile strength, elongation at break, and the like. They can also exhibit anisotropy as shown by their electrical and optical properties. They can be rendered conductive by doping. Methods of preparing the novel composite articles are disclosed as well.

Description

CONDUCTIVE POLYMER BLENDS AND METHODS FOR MAKING THE SAME

Description

This work was supported by the Air Force Office of Scientific Research (AFOSR 90-0283) . The United States Federal Government may have certain rights to this invention.

Field of the Invention

This invention relates generally to conducting polymers, to ordered conjugated polymer precursors to conducting polymers, and to methods for making the same. More particularly, it relates to polymer blends and/or composites which contain conjugated polymers together with nonconjugated carrier polymers so as to provide shaped articles such as fibers, tapes, rods and films which can be rendered conductive and which also exhibit excellent mechanical and optical properties.

Background

Conjugated polymers and conducting polymers based on them were discovered in the late 1970s. They offer unigue optical properties and the possibility of combining the important electronic and optical properties of semiconductors and metals with the attractive mechanical properties and processing advantages of polymers. However, the initial conjugated polymer systems were insoluble, intractable, and non elting (and thus not readily processable into oriented structures) with relatively poor mechanical properties.

In recent years, progress has been made toward specific conjugated polymer systems which are more soluble and thereby more processable. For example, the poly(3-alkylthiophene) derivatives (P3ATs) of polythiophene are soluble and meltable with alkyl chains of sufficient length, and the P3ATs have been processed into films and fibers. See, e.g., Hotta, S., et al., Macromolecules. 2.0:212 (1987); Nowak, M. , et al. , Macromolecules. .12:2917 (1989); Eisenbaumer, R.L. , et al., Synth. Met.. £6.:267 (1988). However, because of the moderate molecular weights and/or the molecular structures of these polymers, the mechanical properties (modulus and tensile strength) of fibers and films, etc., of the P3ATs are modest and limit their use.

Alternative methods of processing conjugated polymers have been developed. For example, conjugated systems based on poly(phenylenevinylene) ("PPV") and alkoxy derivatives of PPV have been synthesized via the "precursor polymer" route. See, for example, U.S. Patent Nos. 3,401,152 and 3,706,677 to Wessling et al.; Gagnon et al., Am. Chem. Soc. Polym. Prepr. 25:284 (1984); Momii et al., Chem. Lett. !_'.1201-4 (1988); and Yamada et al., JCS Chem. Commun. 19_.:1448-9 (1987). In the first step of this route, a saturated precursor polymer is synthesized. The precursor polymer is soluble and can be processed into the desired final shape. The precursor polymer is thermally or chemically converted into the conjugated polymer during or after the forming into desired final shape. Tensile drawing can be carried out during the -conversion. Thus, significant. chain extension and chain alignment of the resulting conjugated polymers can be achieved. Although the precursor polymer route may offer advantages, the multi-step synthesis is complex, makes the resultant materials relatively expensive, and limits their utility. _

On the other hand, many nonconjugated polymers such as polyolefins, for example, ultra-high molecular weight ("UHMW") polyethylene ("PE") can be chain extended and chain-aligned by first dissolving the polymer in an appropriate solvent at an elevated temperature, then

10 forming a gel by cooling, and subsequently carrying out tensile drawing at selected conditions (temperature, time, etc.) to yield fibers and films etc. with the truly outstanding mechanical properties which characterize high-performance polymers (see Table 1 below) . -_ Today, most polymers (such as UHMW PE) with outstanding mechanical properties are insulators. It would clearly be desirable to render such materials conducting. Previous attempts to render such materials conducting have utilized the general method of filling

20 them with a volume fraction of conducting material such as particles of carbon black, or metal flakes or particles (for example, silver flakes) . Addition of such fillers at sufficiently high quantity to yield connected conducting paths (i.e., to be above the percolation

-25 threshold; for example, typically about 16% v/v for approximately spherical particles) results in moderate electrical conductivity, but at the expense of the material's mechanical properties. That is, tensile strength and elongation at break are severely reduced by

30 incorporation of the fillers.

Similarly, most polymers with outstanding mechanical properties are either not readily dyed, or, when pigmented, exhibit some loss of tensile strength or modulus, or both.

35 Thus, the ability to obtain conducting polyolefins and/or polyolefins with optical properties or other polymers with attractive mechanical properties and the ability to fabricate conjugated/conductive polymers into shaped articles such as fibers, films and the like remains seriously limited.

To further understand^"the background of this invention note should be taken of the following references:

A.O. Patil, A.J. Heeger and F. Wudl, Che . Rev.

88: 183 (1988).

R. Silbey, in "Conjugated Polymeric Materials:

Opportunities in Electronics, Optoelectronics and Molecular electronics", NATO ASI Series,

Series E: Applied Sciences- Vol. 182, Ed. by

J.L. Bredas and R.R. Chance; and references therein.

A. Andreatta, S. Tokito, P. Smith and A.J.

Heeger, Mol. Crvst. Liq. Cryst.. 189: 169

(1990) .

S. Kivelson and A.J. Heeger, Synth. Met. 22:

371 (1988) .

P. Smith and P. Lemstra, J. Mater. Sci. , 15: - 505 (1980) .

A. Fizazi, J. Moulton, K. Pakbaz, S.D.D.

Rughooputh, Paul Smith and A.J. Heeger, Phys.

Rev. Let. 64: 2180 (1990) .

P. Smith, P.J. Lemstra, J.P.L. Pijpers, and A.M. Kiel, Colloid and Poly . Sci. 259: 1070

(1981) .

L.S-. Lauchlan, S. Etemad, T.-C. Chung, A.J.

Heeger and A.G. MacDiarmid, Phvs. Rev. B27:

2301 (1983) . Y. Suzuki, P. Pincus and A.J. Heeger, Macromolecules 23: 4730 (1990) .

Disclosure of the Invention

It is accordingly an object of the present invention to overcome the aforementioned disadvantages of the prior art and to provide composites of conjugated polymers, which are both electrically conductive and exhibit excellent mechanical properties.

It is additionally an object of the present invention to provide composites of selected carrier polymers and conjugated polymers, said composites exhibiting the varied optical characteristics of the conjugated polymers as well as excellent mechanical properties.

It is also an object of the present invention to provide shaped articles (fibers, tapes, fabrics, and the like) from composites of selected carrier polymers and conjugated polymers, said composites being electrically conductive and exhibiting excellent mechanical properties.

It is another object of the present invention to provide shaped articles (fibers, tapes and the like) from composites of selected carrier polymers and conjugated polymers, said composites exhibiting the varied optical characteristics of the conjugated polymers as well as excellent mechanical properties.

It is still another object of the invention to provide oriented fibers, tapes and the like from composites of selected carrier polymers and conjugated polymers, said composites being electrically conductive and exhibiting excellent mechanical properties.

It is still another object of the invention to provide oriented fibers, tapes and the like from σomposites of selected carrier polymers and conjugated polymers, said composites exhibiting the various optical properties characteristic of. the conjugated polymers as well as excellent mechanical properties.

It is a further object of the invention to provide methods of making the aforementioned shaped articles from composites of selected carrier polymers and conjugated polymers, said composites being electrically conductive and exhibiting excellent mechanical properties.

It is another object with the invention to provide carrier polymer/conjugated polymer composites which have their molecules oriented relative to one another have significant degrees of anisotropy as evidenced by their absorption and photoluminescence properties.

Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art on examination of the following, or may be learned by practice of the invention.

In one aspect of the invention, shaped, articles such as fibers, tapes, rods, and films which retain the desirable properties of conjugated/conductive polymers are fabricated from a mixture of nonconjugated "carrier" polymer; for example, from ultra-high molecular weight polyethylene (UHMW PE) and a conjugated polymer or conjugated polymer precursor. Initially, a relatively dilute solution is made of a desired quantity of soluble conjugated polymer (such as, for example, the P3ATs) in a suitable solvent together with carrier polymer. Alternatively, the solution can be made of a quantity of a polymeric precursor or conjugated polymer which may be converted either chemically or thermally to a desired conjugated polymer (as in the case of PPV and its derivatives) . A mechanically coherent, shaped structure is then prepared, e.g., in the form of a fiber, tape, film, or the like; this structure is comprised of the carrier polymer and either the conjugated polymer or the precursor. The blend fibers, tapes, films, or the like are then subjected to distortion such as tensile drawing to yield the desired shaped articles.

Surprisingly, the inventors herein have found that composite articles fabricated through this processing route have excellent mechanical properties, i.e., with respect to tensile strength, elongation at break, and the like, and can be made electrically conductive as well. If desired, the composite articles may also be fabricated so as to retain color, or display other attractive optical characteristics.

Thus, in a preferred embodiment, conjugated polymer shaped articles can be formed by the process of

(a) providing a carrier solution made up of (i) carrier solvent, (ii) nonconjugated flexible chain carrier polymer, and

(iii) conjugated polymer or^* conjugated polymer precursor;

(b) forming this carrier solution, before or after gelling the solution, thereby yielding a body having a first shape;

(c) physically distorting the first shape of the body, and removing the carrier solvent before, during or after the distorting to yield the desired shaped article. In preferred embodiments, the physical distorting is carried out anisotropically so as to yield an oriented structure in the carrier polymer and in the conjugated polymer. The orientation of the conjugated polymer leads to anisotropic absorption and photoluminescence properties for the shaped article.

In some embodiments the distorting is carried out by drawing, particularly to very high draw ratios (greater than 10 and often up to as much as 30 or 100 or more) .

In other aspects, this invention provides the conjugated polymer products which this process makes possible and conductive polymer products which result from doping the conjugated polymer with ions.

Brief Description of the Figures

Figure 1 illustrates the chemical structure of the poly(3-alkylthiophenes) as discussed in Example 1.

Figure 2 schematically illustrates the synthesis of poly(2,5-dimethoxy-p-phenylenevinylene) (PDMPV) as described in Example 10.

Figure 3 schematically illustrates two routes for the synthesis of poly(2-methoxy-5(2'-ethylhexyloxy)- p-phenylenevinylene) (MEH-PPV) as described in Example 15.

Figure 4 is a graph showing anisotropic absorption for an oriented film at a draw ratio of about 50 of PE/MEH-PPV for polarization both parallel to (solid) and perpendicular to (dashed) the draw axis and for a spin-cast film (dot-dashed) , all at 8OK. The scattering loss from a UHMW-PE film of comparable thickness and draw ratio is shown (dotted) for comparison) . Figure 5 is a graph showing anisotropic absorption for a nonoriented free-standing film of PE/MEH-PPV (dashed) , absorption parallel to draw axis of the oriented film of PE/MEH-PPV (solid) , and anisotropic absorption of the spin-cast film (dot-dashed) all at 8OK. The inset compares absorption parallel to draw axis of the oriented film at 80K (solid) and at 300K (dashed) .

Figure 6 is a graph depicting anisotropy in the 80K photo-luminescence spectrum, from an oriented film of PE/MEH-PPV for parallel pumping; the upper solid curve is photo-luminescence spectrum parallel to draw axis; the lower solid curve is photo-luminescence spectrum perpendicular to draw axis; the dotted curve is photo- luminescence spectrum perpendicular to draw axis scaled (times 30) for clarity. The insert shows the dependence of photo-luminescence spectrum on the polarization angle relative to the chain axis (the solid curve is a fit to COS²©) .

Figure 7 shows the anisotropic electro- absorption (electric field modulated absorption) of a film of oriented PE/MEH-PPV having a 6% volume fraction Of MEH-PPV.

Modes for Carrying Out the Invention

In essence, the method of the present invention involves five steps: (a) the dissolution of the appropriate carrier polymer and either a soluble conjugated polymer or a soluble precursor to a conjugated polymer in a suitable carrier solvent; (b) the preparation of a shaped article from the polymer solution by forming; (c) the gelling of the polymer solution either before or after it is formed into the shaped article; (d) the physically distorting of the shaped article through tensile drawing or like process to chain-extend or chain-align the carrier polymer, and to chain-extend and chain-align the conjugated polymer as well; and (e) the removing of the solvent before, during, or after the physical distorting step. In the process, the gelling of step c can be arrived at as part of step b and solvent removal can accompany the gelling or distorting so as to give a three or four step process. Similarly, where a precursor is used in step (a) (for example, in the route to PPV and its derivatives) , the tensile drawing or distorting can be carried out at a temperature selected to. serve to convert the precursor polymer to the conjugated polymer. The articles formed by the present process—typically fibers, rods tapes, or films of the otherwise colorless and insulating carrier polymer—can be rendered electrically conductive by doping, exhibit excellent mechanical properties, and may or may not be colored or display other optical characteristics.

A. Definitions

For reference, the various categories of mechanical properties of polymers are summarized in the following table:

Table 1 Typical Mechanical Properties of Polymer Types

Modulus (GPa) Tensile Strength (GPa)

Although the ranges given in the table are approximate, the numbers serve to delineate the various types of applications.

A "shaped article" as used herein is intended to mean a mechanically coherent object having a defined form, for example, a fiber, rod, film, or tape. The inventiveness of the present process lies in the ability to form shaped articles (by means of solution processing) of polymers such as polyolefins for example ultra high and molecular weight polyethlene which are electrically conductive and exhibit excellent mechanical properties over the full range indicated in Table 1. They also can exhibit anisotropic absorption and emission spectra.

A "conjugated" polymer as used herein means a polymer having a 7r-electron network which allows for electron transfer substantially throughout its molecular structure. Conjugated polymers are typically highly colored because of the strong absorption associated with the π-π* transition; the color, if any, will depend on the specific polymer, for the energy of the π-π* transition is determined by the polymer structure.

By "substantially nonconducting" as used herein to describe the carrier polymer is meant a conductivity σ of less than about 10 S/cm and preferably less than IO^"9 S/cm. The conductivity σ of the composite materials provided and described herein is given as-the conductivity after doping, i.e., during or after preparation of the composite as described herein, the material is rendered conductive by either p-type (oxidative) or n-type (reductive) doping using standard dopants and techniques.

A "precursor" polymer as used herein is a partly saturated polymer which can be converted to a final conjugated polymer by thermal treatment or by chemical treatment, or both. The precursor polymer is soluble in common solvents, whereas the converted conjugated polymer is either not soluble in such solvents or much less soluble than the precursor polymer.

A polymer "composite" or "blend" as used herein means a structural mixture of two or more polymeric materials which may or may not be covalently bound to one another.

An "oriented" material as used herein is intended to mean a polymeric structure in which individual polymeric chains are substantially linear and parallel.

Generally, "flexible chain" polymers are structures which allow for more variation in bending angle, along the chains (characteristic ratio C_ω typically less than 10) , while "rigid rod" polymers tend to be straighter and more highly oriented (character¬ istic ratio C_ffl typically greater than about 100) . See P.J. Flory, Statistical Mechanics of Chain Molecules, N.Y., Wiley & Sons - Interscience, 1969, p. 11.

B. Solution Processing i) Carrier Polymers.

The criteria for the selection of the carrier polymer are as follows. The polymer is preferably a substantially nonconducting, flexible-chain polymer which allows for the formation of mechanically coherent structures (fibers, films, rods, tapes, etc.) at low concentrations, and which is stable with respect to the solvent used in processing. Low concentrations of carrier polymer are preferred in order to minimize processing difficulties, i.e., excessively high viscosity or the formation of gross inhomogeneities; however, the concentration of the carrier should be high enough to allow for formation of coherent structures. Preferred carrier polymers are high molecular weight (weight averaged molecular weight greater than about 50,000, more preferably greater than about 100,000 such as greater than about 500,000) flexible-chain polymers, such as polyethylene, isotactic polypropylene, polyethylene oxide, polystyrene, poly(aerylonitrile) , polyketones, polyesters, polyamides, and the like, and particularly preferred carrier polymers are polyethylene and polypropylene. Under appropriate conditions, which can be readily determined by those skilled in the art, these macromolecular materials enable the formation of coherent structures from a wide variety of liquids, including water, acids, and numerous polar and nonpolar organic solvents. Structures manufactured using these carrier polymers have sufficient mechanical strength at polymer concentrations in the carrier solvent as low as 1%, even as low as 0.1%, by volume, to enable the subsequent processing into the desired_shaped article.

Mechanically coherent structures can also be prepared from lower molecular weight flexible chain polymers, but generally, higher concentrations of these carrier polymers are required. ^"Higher concentrations may have an undesirable effect on the drawability and properties of the final products.

Selection of the carrier polymer is made primarily on the basis of compatibility of the final conducting polymer and its reactants, as well as with the solvent or solvents used. For example, blending of polar conducting polymers generally requires carrier structures that are capable of codissolving with or absorbing polar reactants. So, too, the conjugated polymer and carrier polymer are often soluble in one another. Examples of such coherent structures are those comprised of poly(vinyl alcohol), poly(ethylene oxide), etc., and suitable liquids. On the other hand, if the blending of the final polymer cannot proceed in a polar environment, nonpolar carrier structures are selected, such as those containing polyethylene, polypropylene, poly(butadiene) , and the like.

It should of course be noted that more than one carrier polymer may be used to form the carrier solution and ultimately become a part of the final composite; i.e., mixtures of two or more carrier polymers may be incorporated into the initial carrier solution.

ii) The Carrier Solvent.

The carrier solvent is one in which the carrier polymer is substantially soluble and one which will not interfere with the subsequent admixture with the conjugated polymer, gelation and formation into the first body.

Typically, organic solvents are used. These can include halohydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride, aromatic hydrocarbons such as xylene, benzene, toluene, other hydrocarbons such as decaline, and the like. Mixed solvents can be used, as well. Depending upon the nature of the carrier polymer, polar solvents such as water, acetone, acids and the like may be suitable. These are merely a representative exemplication and the solvent can be selected broadly from materials meeting the criteria set forth above.

iii) The Conjugated Polymer.

The conjugated polymers used herein include the wide range of conjugated polymers known in the art. These include, for example, poly(2-methoxy,5-(2'-ethyl- hexyloxy)-p-phenylenevinylene) or "MEH-PPV", P3ATs, poly(3-alkylthiophenes) (where alkyl is from 6 to 16 carbons), such as poly(2,5-dimethoxy-p-phenylene vinylene)-"PDMPV", and poly(2 ,5-thienylenevinylene) ; poly(phenylenevinylene) or "PPV" and alkoxy derivatives thereof; and polyanilines.

In an alternative embodiment, a polymeric precursor which may be converted to the desired conjugated polymer is used. The precursor must, as above, be soluble in the solvent. It will typically be readily converted to the ultimately desired polymer via either thermal or chemical means. If such is the case, the thermal or chemical treatment may take place either before, during, or after gelation. Examples of soluble precursor polymers include those described by Wessling et al. in U.S. Patent Nos. 3,401,152 and 3,706,677, cited supra (i.e., as precursors to PPV) as well as those described by Gagnon et al., Momii et al., and Yamada et al. , all cited supra. _

iv) Relative Amounts in Carrier Solution.

Turning now to the issue of concentration, it is of crucial importance that the first structure as formed have sufficient mechanical coherence for further handling during the formation of the final polymer blend. Therefore, the initial concentration of the carrier in the solution polymer generally is selected above 0.1% by weight, and preferably above about 0.2% or 0.75% by weight, basis solvent and more preferably from about 0.1% by weight to about 50% by weight. More preferably, the concentration of the carrier polymer in the initial solution is from about 0.1% by weight to about 25% by volume. The final composite is one in which the conjugated polymer represents at least about 0.1 wt.% of the total polymer in the composite, more preferably from about 0.2 wt.% to about 90 wt.%, most preferably from about 0.5 wt.% to about 50 wt.%. In some settings it is desired to provide a final composite in which the conjugated (conducting) polymer represents at least about 5% of the total composite, preferably at least about 10% and more preferably at least about 20% The concentration of conjugated polymer (or precursor) in the carrier solution should be set to provide this relationship with the carrier polymer.

At lower concentrations of total polymer in the solution, such as 0.1% to about 25%, the polymer chains are in a less tangled state which can be advantageous when making highly aligned, linear structures. C. The Forming Step

The carrier solution is formed into a selected shape, e.g., a fiber, tape, _rod, film or the like, by extrusion or by any other suitable method.

D. The Gelation Step

Gels can be formed from the carrier solution in various ways, e.g., through chemical crosslinking of the macromolecules in solution, swelling of crosslinked macromolecules, thermoreversible gelation, and coagulation of polymer solutions. In the present invention, the two latter types of gel formation are preferred, although under certain experimental conditions, chemically crosslinked gels may be preferred.

Thermoreversible gelation refers to the physical transformation of polymer solution to polymer gel upon lowering the temperature of a homogeneous polymer solution (although in exceptional cases a temperature elevation may be required) . This mode of polymer gelation requires the preparation of a homogeneous solution of the selected carrier polymer in an appropriate solvent according to standard techniques known to those skilled in the art. The polymer solution is cast or extruded into a fiber, rod, or film form, and the temperature is lowered to below the gelation temperature of the polymer in order to form coherent gels. This procedure is well known and is commercially employed, e.g., for the formation of gels of high molecular weight polyethylene in decalin, paraffin oil, oligomeric polyolefins, xylene, etc., as a precursor for high-strength polyolefin fibers and films.

"Coagulation" of a polymer solution involves contacting the solution with a nonsolvent for the dissolved polymer, thus causing the polymer to precipitate. This process is well known, and is commercially employed, for example, in the formation of rayon fibers and films, in the spinning of high-performance aramid fibers, etc.

The gelation step can be carried out before, during, or after the "Forming Step". Solvent is removed from the carrier solution during the gelation step or thereafter. Solvent can also be removed during the distorting step. In many cases solvent is removed in several stages, during and after gelatio ..

Alternatively, "dry" spinning can be employed. In this method, the solvent is removed by evaporation, leading to the desired carrier structure formation.

E. The Distorting Step

It is frequently desirable and preferred to subject the carrier polymer/conjugated polymer or precursor composite during or after forming into an initial shaped article is subjected to mechanical deformation, typically by stretching at least about 100% in length, after the forming step. Deformation of polymeric materials is carried out in order to orient the macromolecules in the direction of draw, which deformation results in improved mechanical properties. Maximum deformation of thermoreversible gels are generally substantially greater than melt processed materials. (P. Smith and P.J. Lemstra, Colloid and Polym. Sci., 258:891 (1980). The large draw ratios possible with certain thermoreversible gels are also advantageous if composite materials may be prepared with materials limited in their drawability due to low molecular weights. In the case of conducting polymers, not only do the mechanical properties- improve, but, more importantly, the electrical conductivity and optical properties also often display both anisotropy and drastic enhancement upon tensile drawing.

In accord with the. present invention, the carrier/conjugate formed articles are typically subjected to substantial deformation such as a draw ratio (final length:initial length) of at least about 1:1 and preferably at least 10:1 and more preferably at least 20:1. This drawing has the effect of physically orienting not only the carrier molecules but also the molecules of conjugated polymers. This leads to advantages such as anisotropic optical and electrical properties, for the carrier/conjugate composites as a whole.

F. Doping

The polymer composite materials can be rendered conductive by doping during or after fabrication into the shaped articles.

This can be done by doping with acceptors or donors. In acceptor doping, the backbone of the acceptor-doped polymer is pxidized, thereby introducing positive charges into the polymer chain. Similarly, in donor doping, the polymer is reduced, so that negative charges are introduced into the polymer chain. It is these mobile positive or negative charges which are externally introduced into the polymer chains that are responsible for the electrical conductivity of the doped polymers.

G.^' Polymer Properties

The materials prepared according to the aforementioned method are thus shaped polymer blends or composites, i.e., fibers, rods, films, tapes, or the like, which are electrically conductive and which display superior mechanical properties. More specifically, the composites provided herein can have an electrical conductivity σ of at least about 10 —7 S/cm and can in some cases have an electrical conductivity σ of at least about 0.75 S/cm and a Young's modulus E of at least about

0.4 and preferably at least about 0.5 GPa. This process can provide materials in which the product of σ and E is at least about 0.3 (GPa) (S/cm) or even at least about 1 0 (GPA) (S/cm) or even at least about 5 (GPa) (S/cm) .

It is possible using this invention to achieve composites having a modulus of at least about 10 GPa and a conductivity of at least 10 —7 S/cm; or even 10—3 S/cm or even 0.75 S/cm or more or even 1.0 S/cm or more.

15 It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, that the foregoing description as well as the examples which follow are intended to illustrate and not to limit the scope of the 0 invention. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains. Experimental

Mechanical Properties: The mechanical

__ properties of the various materials described in the examples were tested at room temperature using an Instron Tensile Tester Model 1122. The initial length of the test specimen was from 10 to 25 mm, and the crosshead speed was 10 mm/min. The modulus of the fibers was taken

_3Q to be the initial, or Young's, modulus. The denier

(linear density) of the samples was measured by weighing 100 to 200 mm of the fibers. The cross- sectional areas . of the fibers were determined from a knowledge of the linear density in combination with knowledge of the

₃₅ polymer or polymer composite density. Electrical Conductivity Measurements: A four- probe technique for conductivity measurement was used to measure the conductivity o¥_the materials herein. The four contacts were made on the surface of the sample fibers in a linear array. The testing probe was placed into a evacuable chamber from which ambient atmosphere was removed and into which iodine vapors were introduced. The vapor pressure of iodine at room temperature was 0.34 mm Hg. A current (1) was passed through the outermost probes and the voltage drop measured across the innermost probes. The voltage measurement was carried out by means of a high-impedance voltmeter and is considered to be essentially a zero current measurement. Hence, the contact resistance between the innermost probes and the sample is minute, since the current flow through the voltmeter is minute. Ohmic contacts were carried out using conductive carbon paint contacts (SPI, Inc., West Chester, PA) in which platinum electrodes were attached to the samples by means of finely divided graphite in .isopropyl alcohol. The resistance (R) of the fibers was first measured by the four-probe technique. The length (L) was measured with a ruler, and the cross section area (A) was determined gravimetrically. The conductivity of the fiber was then calculated by the following equation: σ = (L/AR) where a is the electrical conductivity.

Example 1 The poly(3-alkythiophenes) were prepared by direct oxidation of the appropriate 3-alkylthiophene by FeCl₃ (J.-E. Osterholm et al., Svnth. Met.. 28:C435 (1989)). Figure 1 shows the chemical structure of the poly(3-alkylthiophenes) . A 100%-by-weight film of poly(3-octylthiophene) was cast onto glass from a 3 wt.' solution in chloroform (Fisher Scientific) . The films were dried under nitrogen and lifted from the substrate by soaking in methanol (Fisher Scientific) . Appropriate samples were cut from the dried films and subsequently drawn to their maximum draw ratio (L+ΔL/L) at a variety of temperatures on the Instron Tensile Tester equipped with an oven capable of maintaining such temperatures.

The maximum attained draw rations were as follows:

Temperature f°C) Draw Ratio

25 3.1

80 4.5

90 5.3

95 5.3

100 6.1

105 6.1

110 6.2

120 5.0

130 1.7

Example 2 A 100%-by-weight film of poly(3-dodecylthio- phene) (PDDT) was cast onto glass from a 3 wt.% solution in chloroform (Fisher Scientific) . The films were dried under nitrogen and lifted from the substrate by soaking in methanol (Fisher Scientific) . A 100%-by-weight poly(3-octylthiophene) (POT) fiber was produced by wet spinning into acetone (Fisher Scientific) according to standard procedures. The fibers and films of PDDT were cut to appropriate sizes and drawn to various draw ratios at 100°C in air. The fibers and films of the POT and PDDT have a lustrous greenish appearance on reflection and are red in transmission. The mechanical properties of the drawn polymers are listed below:

These data illustrate the relatively poor mechanical properties of the drawn, soluble poly(alkylthiophenes)

Example 3 The poly(3-dodecylthiophene) samples of Example 2 were drawn, in air, at 100°C to various draw ratios. The poly(3-σctylthiophene) samples of Example 2 were drawn, in air, at 105°C to various draw ratios. The drawn poly(3-octylthiophene) samples were then doped at room temperature in iodine vapor and measured using a 4-probe device. The poly(3-dodecylthiophene) samples were doped at.40°C in^'1.74 wt.% solution of 488 mg N0SbF_g (Alfa Chemicals) in 27.51 g acetonitrile (Aldrich) . The conductivities of the films or ibers reached constant values of:

Draw Ratio Conductivity (S/cm)

Poly (3-octylthiophene)

1 6 0 2.8 17

3.8 28

Poly(3-dodecylthiophene)

15 1 17

2.8 52

3.1 66

Example 4

_₀ Decalin (decahydronaphthalene, Aldrich) ; 9.7 g was mixed, at room temperature, with 225 mg of polyoctylthiophene in a 50 ml test tube. This stirred mixture was blanketed with nitrogen gas and heated to 104°C, at which time 75 mg of ultra-high molecular weight

_₅ polyethylene (Hostalen GUR 415, Hoechst) was added.

Subsequently, the mixture was heated to a temperature of 155°C, at which point stirring was stopped, and the temperature was raised further to 150°C for 1 hour. A viscous orange liquid was obtained. The solution was

30 cooled, and the red-orange gel was transferred to a laboratory-scale spinning apparatus. A polyethylene/ polyoctylthiophene gel fiber was spun into a nonsolvent coagulating bath according to standard procedures.

35 The composite fiber was of 68 denier, and dark red-brown in color.

The polyoctylthiophene content of this composite fiber was 75% by weight.

The mechanical properties of the composite fiber were determined to be as follows for various draw ratios, with the samples being drawn at^' 105„C in air.

Example 5 The polyoctylthiophene/polyethylene composite fiber of Example 4 was dried and drawn, in air, at 105°C to various draw ratios. The drawn samples were then doped at room temperature in iodine vapor using a 4- probe device. The conductivities of the composite fibers reached constant values of:

Draw Ratio Conductivity (S/cm) 1 2

4.1 22 6 32 30 20 Example 6 Decalin (decahydronaphthalene, Aldrich) ; 9.7 g was mixed, at room temperature, with 200 mg of polydodecylthiophene in a 50 ml test tube. This stirred mixture was blanketed with nitrogen gas and heated to 104°C, at which time 200 mg of ultra-high molecular weight polyethylene (Hostalen GUR 415, Hoechst) was added. Subsequently, the mixture was heated to a temperature of 115°C, at which point stirring was stopped, and the temperature was raised further to 150°C for 1 hour. A viscous orange liquid was obtained. The solution was cooled, and the red orange gel was transferred to a laboratory-scale spinning apparatus. A polyethylene/ polydodecythiophene gel fiber was spun according to standard procedures, and subsequently drawn at 105°C in air.

The composite fiber was of 600 denier, and dark red-brown in color. The polydodecylthiophene content of this composite fiber was 50% by weight.

Elongation at Break

(%)

8 2.49 0.36 28

Exam le 7

The polydodecylthiophene/polyethylene composite fiber of Example 6 was drawn, in air, at 105°C. The drawn samples were doped at 40°C in -1.75 wt. % solution of 488 mg N0SbF₆ (Alfa Chemicals) in 27.5 g acetonitrile (Aldrich) . The doped samples were removed from the doping solution, washed 3 times in dry acetonitrile, and then air dried. The conductivities were measured using a 4-point probe device. The conductivities of the composite fibers reached constant values of:

Draw Ratio Conductivity (S/cm)

1 0.2

8 30

Example 8 A series of polyoctylthiophene - (POT)/polyethylene composite fibers were prepared such that the total polymer concentration in the gel was maintained at 1.5% by weight. All composite fiber samples were drawn to various draw ratios at 105°C in air. A comparison of the moduli from composite fibers in _Q Example 8 combined with data from Example 2 shows the drastically improved mechanical properties of the composite fibers.

5

0

5 The composite fibers were of the following

30%-bv-weight POT

Example 9 The polyoctylthiophene/polyethylene composite fibers of Example 8 were dried and drawn, in air, at 105°C to various draw ratios. The samples were then doped at room temperature in iodine vapor to constant measured potentials using a 4-point probe device. The conductivities of the composite^" fibers reached constant values of:

20%-b -weight POT

90%-by-weight POT

Draw Ratio _ Conductivity (S/cm) 1 7

3.1 25

5.0 46

6.3 39

Example 10

A. Synthesis of precursor polymer of poly(2.5-dimethoxy- p-phenylenevinylene) (PDMPV) :

The synthesis of the precursor polymer was carried out essentially according to the procedure described in the literature (T. Momii et al., Chem. Lett.. 1201 (1987); S. Tokito et al.. Polymer, to be published 1991) as shown in Figure 2. The polymerization was carried out by mixing equal volumes of 0.4 M aqueous monomer and 0.4 M aqueous NaOH at 0-l0°C for 1 hour. After 5 minutes reaction, the mixture formed a transparent gel. This gel was dissolved in distilled water followed by the addition of an excess amount of p- toluene sulfonic acid sodium salt (PTS) , giving a white precipitate of the sulfonium salt polymer with a p- toluene sulfonic acid counter anion. The precipitate was filtered and dissolved in methanol and reacted at 20°C. After 50 hours of stirring, a powdery precursor polymer was extracted; this polymer is soluble in common organic solvents such as chloroform, tetrahydrofuran, and dichloromethane. The precursor polymer was purified by reprecipitation from chloroform, solution into hexane. B. Preparation of Carrier Gel:

Purified precursor polymer (PDMPV, 50 mg) was dissolved in a mixture of 3_ml xylene and 0.5 ml chloroform. The solution of precursor polymer was mixed at 60°C with 62 mg of ultra-high molecular weight polyethylene (Hostalen GUR 412, Hoechst) in a 20 ml test tube. This mixture was heated at a temperature of 130°C for 30 minutes with stirring, and then cooled to ambient temperature. The resultant composite gel was yellow. Composite filaments of polyethylene and PPMPV were spun at 130°C using laboratory scale equipment. The as-spun filament was wound onto a bobbin and dried in a vacuum oven overnight.

C. Drawing of Composite Filament:

The dried composite filaments (PDMPV/PE = 46 wt% PDMPV) were drawn at 140°C under nitrogen flow using laboratory-scale drawing system. The draw ratio was varied by changing the speed of the two motors. The drawn fibers were heated to convert precursor polymer to PMPV at 110°C for 10 hours under nitrogen gas containing a small amount of the vapor of hydrochloric acid (the nitrogen gas was first passed over HC1 at room temperature) . The acid catalyst plays an important role in the conversion reaction (see T. Momii et al. , Chem. Lett. , 1201 (1987)). After 10 hours of heating, the highly oriented composite fibers which contained 60 wt% of PE and 40 wt% of PDMPV, were obtained. The composite fibers were red with a shiny metallic luster. Mechanical properties of the composite fiber are listed below. These values are comparable to the values of highly oriented polyethylene fiber. (P. Smith and P.J. Lemstra, J. Mat. Sci.. 15.:505 (1980)) and are characteristic of high-performance polymers (see Table 1).

Example 11 The composite fibers (40 wt%, PDMPV) of Example 10 were doped with iodine by exposing the fibers to iodine vapor at room temperature. The conductivities of the doped composite fibers were measured by the conventional 4-probe method. The conductivities are listed below:

The mechanical properties of the doped composite fibers are listed below:

The composite fibers prepared in Example 10(B) were drawn and converted simultaneously. Nitrogen gas containing a small amount of hydrochloric acid vapor was introduced into the tube furnace during heating and drawing.

The mechanical properties are listed below.

Example 13 The composite fibers (40 wt%, PDMPV) of Example 11 were doped with iodine by exposing the fibers to iodine vapor at room temperature. The conductivities of the doped composite fibers were measured by the conventional 4-probe method. The conductivities are listed below:

Example 14 The composite filaments with different concentrations of precursor.polymer were prepared according to Example 10(B). The composite filaments were drawn and converted by using the same system as described in Example 12.

The mechanical properties and conductivities of the composite fibers (concentrations of precursor, 20 wt%, 29 wt%, and 31 wt%) are listed below:

PDMPV = 20 wt%

PDMPV = 31 Wt%

Example 15 This example involves the preparation and testing of a highly drawn polymer composite made up of 99% ultra-high molecular weight polyethylene and 1% conjugated polymer, poly(2-methoxy,5-(2'ethyl-hexyloxy)- p-phenylenevinylene) "MEH-PPV". It follows the preparative scheme shown in Figure 3.

Monomer Synthesis

1. Preparation of l-Methoxy-4-(2-Ethyl-Hexyloxy)Benzene

A solution of 24.8 g (0.2 mole) of 4-methoxy phenol in 150 ml dry methanol was mixed under nitrogen with 2.5 M solution of sodium methoxide (1.1 equivalent) and refluxed for 20 min. After cooling the reaction mixture to room temperature, a solution of 2- ethylbromohexane (42.5 ml, 1.1 equivalent) in 150 ml methanol was added dropwise. After refluxing for 16 h, the brownish solution turned light yellow. The methanol was evaporated and the remaining mixture of the white solid and yellow oil was combined with 200 ml of ether, washed several times with 10% aqueous sodium hydroxide, H₂0 and dried over MgS0₄. After the solvent was evaporated, 40 g (85%) of yellow oil was obtained. The crude material was distilled under vacuum (2.2 mm Hg, b.p. 148-149°C)_/ to give a clear, viscous liquid. H NMR (CDC1₃) δ 6.98 (4H, s, aromatics), 3.8 (5H, t, 0-CH₂, O- CH₃), 0.7-1.7 (15 H, m, C₇H₁₅. IR (NaCl plate) 750, 790, 825, 925, 1045, 1105, 1180, 1235, 1290, 1385, 1445, 1470, 1510, 1595, 1615, 1850, 2030, 2870, 2920, 2960, 3040. MS. Anal. Calc. for C₁₅H₂₄0₂: C, 76.23; H, 10.23; 0, 13.54. Found: C, 76,38; H, 10.21; 0, 13.45. 2. Preparation of 2.5-bis(Chloromethyl)-l-Methoxy-4- (2-Ethyl-Hexyloxy)Benzene

To the solution of_4.9 g (20.7 mmoles) of compound (1) in 100 mi p-dioxane cooled down to 0-5°C, 18 ml of cone. HC1, and 10 ml of 37% aqueous formalin solution was added. Anhydrous HCl was bubbled for 30 min, the reaction mixture warmed up to R.T. and stirred for 1.5-2 h. Another 10 ml of formalin solution was added and HCl gas bubbled for 5-10 min at 0-5°C. After stirring at R.T. for 16 h, and then refluxed for 3-4 h. After cooling and removing the solvents, an off-white "greasy" solid was obtained. The material was dissolved in a minimum amount of warm hexanes and precipitated by ₅ adding methanol until the solution became cloudy. After cooling, filtering and washing with cold methanol, 3.4 g (52%) of white, crystalline material (mp 52-54°C) was obtained. ¹H NMR (CDC1-) _ 6.98 (2H, s, aromatics), 4.65 (4H, s, CH₂-C1) , 3.86 (5H, t, 0-CH₃, 0-CH₂) , 0.9-1.5 _fJ (15H, m, C_?H₁₅) , IR (KBr) 610, 700, 740, 875, 915, 1045, 1140, 1185, 1230, 1265, 1320, 1420, 1470, 1520, 1620, 1730, 2880, 2930, 2960, 3050. MS. Anal. Calc. for

^C17^H26°2^C12^{: C}' ⁶¹*²⁶' ^H' 7.86; O, 9.60; Cl, 21.27. Found: C, 61.31; h, 7.74; O, 9.72; Cl, 21.39. 5

Polymerization

Preparation of Polv(l-Methoxy-4-(2-EthylheXyloxy-2.5-

Phenylenevinylene) MEH-MPV

To a solution of 1.0 g (3- mmol) of 2,5- bis(chloromethyl)-methoxy-4-(2-ethylhexyloxy)benzene in 20 ml of anhydrous THF was added dropwise a solution of 2.12 g (18 mmol) of 95% potassium tert-butoxide in 80 ml of anhydrous THF at R.T. l. . stirring. The reaction mixture was stirred at ambient temperature for 24 h and ₅ poured into 500 ml of methanol with stirring. The resulting red precipitate was washed with distilled water and reprecipitated from THF/methanol and dried under vacuum to afford 0.35 g (45%_ yield) . UV (CHC1₃) 500. IR (film) 695, 850, 960, 1035, 1200, 1250, 1350, 1410, 1460, 1500, 2840, 2900, 2940, 3040. Anal. Calc. for C₁₇H-₄0₂: C, 78.46; H, 9.23. Found: C, 78.34; H, 9.26.

Molecular weight (GPC vs. polystyrene) 3 x 10 . Inherent viscosity - 5 dl/g (but time dependent due to the tendency to form aggregates) . As is the case with a few other stiff chain polymers, the viscosity increases with standing, particularly in benzene. The resulting solution is therefore thixotropic.

The conjugated polymer is highly colored (bright red-orange) .

Example 16 Preparation of MEH-PPV via precursor polymer route.

Monomer Synthesis

The monomer synthesis is exactly the same as in Scheme 1 of Figure 3.

Polymerization of the Precursor Polymer and Conversion to MEH-PPV

A solution of 200 mg (0.39 mmol) of the monomer salt of Example 15 in 1.2 ml dry methanol was cooled to 0°C for 10 min and a cold degassed solution of 28 mg (1.7 equivalents) of sodium hydroxide in 0.7 ml methanol was added slowly. After 10 min the reaction mixture became yellow and viscous. The above mixture was maintained at 0°C for another 2-3 h and then the solution was neutralized. A very thick, gum-like material was transferred into a Spectrapore membrane (MW .cutoff 12,000-14,000) and dialyzed in degassed methanol containing 1% water for 3 days. After drying in vacuo, 70 mg (47%) of "plastic" yellow precursor polymer material was obtained. UV <CHC1₃) 365. IR (film) 740, 805, 870, 1045, 1075, 1100, 1125, 1210, 1270, 1420, 1470, 1510, 2930, 2970, 3020. Soluble in C₆H₅C1, CgH₃Cl₃, CH₂C1₂, CHC1₃, Et₂0, THF. Insoluble in MeOH.

The precursor polymer was converted (step e of the Scheme) to the conjugated MEH-PPV by heating to reflux (approx. 214°C) in 1,2,4-trichlorobenzene solvent. The product was identical with the material obtained in Scheme 1 of Figure 3.

Carrier Solution Preparation. Article Formation, Gelation, and Drawing.

PE-MEH-PPV blends were prepared by mixing 7.5mg of MEH-PPV (M_w=450,000) in xylene with 0.75 g of UHMW polyethylene (Hostalen GUR 415; M_w=4xl0 ) in xylene such that the PE to solvent ratio was 0.75% by weight. This solution was thoroughly mixed and allowed to equilibrate in a hot oil bath at 126°C for one hour. The solution was then poured into a glass container to cool, forming a gel which was allowed to dry (into a film) . Films were then cut into strips and tensile drawn over a hot pin at 110 - 120°c. Once processed in this manner, the films are extremely durable; repeated thermal cycling and constant exposure to air caused no ill effects. This is presumably due to a combination of the stability of MEH- PPV and to the self-encapsulation advantage of utilizing polymer blends.

The spectra were measured with a 0.3 meter single grating monochrometer, and a mechanically chopped tungsten-halogen light source (resolution at the exit slits was 1.0 nm) ; light was detected by a photomultiplier tube (Hamamatsu R372) , and the output was sent to a lock-in amplifier. The samples were mounted on sapphire substrates which were fit into a copper sample holder and mounted on the cold finger of a vacuum cryostat. To study the polarization dependence of anisotropic absorption, a dichroic sheet polarizer (MG 03 FPG 005) was inserted (on a driven rotational stage) just before the sample. Because of the dilution (1% conjugated polymer) of the gel-processed films, the index is dominated by that of PE so that the reflection losses were limited to a few percent even for relatively thick samples with moderate optical density. Thus, the absorption coefficients, parallel and perpendicular to draw axis, were accurately determined after correcting for the background with a blank substrate. For the photo-luminescence (PL) measurements, the sample was excited by a polarized, mechanically chopped (400Hz) Ar - ion laser (Coherent model 70) beam tuned to 457.9 nm. To determine the polarization dependence of anisotropic photoluminescence, the polarizer was placed at the entrance slit of the monochrometer. All PL spectra were corrected by replacing the sample with an NBS referenced lamp. Absorption spectra were monitored before and after • luminescence runs to insure against optical damage.

The absorption spectra for an oriented free standing film (50:1 draw ratio) of PE/MEH-PPV are shown in Figure 4 for polarization both parallel to and perpendicular to the draw axis and for a spin-cast film (both at 8OK) ; a high degree of macroscopic orientation of the conjugated polymer has been achieved by tensile drawing the gel-processed blend. Moreover, absorption parallel shows a distinct red shift, a sharper absorption onset, and a reduced total band-width compared to the absorption for the spin-cast film. These features, together with the appearance of resolved vibronic structure indicate a significant improvement in the structural order of the conjugated polymer in the oriented blend. The spectra of Figure 4 were scaled (for comparison) to that of the absorption parallel which has a maximum value of 2.2xl0³ cm^"1 at 2.2 eV (1% MEH-PPV in PE) .

Figure 5 compares absorption coefficients of a nonoriented free-standing film of PE/MEH-PPV, of the 0 oriented film of PE/MEH-PPV parallel to draw axis, and of the spin-cast film (all at 8OK) . The spectrum obtained from the nonoriented blend is intermediate between that of the spin-cast film and the oriented blend; it shows the red shift, the sharper absorption onset, the reduced _ total band-width and the emergence of vibronic structure. Thus, even in the nonoriented blend, the MEH-PPV spectra are, in every way, consistent with a significant enhancement of microscopic order. Comparison of the absorption of the oriented film of PE/MEH-PPV with the 0 absorption of the nonoriented film of PE/MEH-PPV shows that there is a sharpening of all spectral features and a clear redistribution of spectral weight into the zero- phono line (i.e. the direct photo-production of a polaron-exciton in its vibrational ground state) . The 5 data thus indicate a further enhancement of structural order by tensile drawing.

The inset to Figure 5 compares the absorption parallel to draw of an oriented free standing film of PE/MEH-PPV at 8OK with that at 30OK. As the temperature

30 (T) is raised, the peak shifts (thermochroism) , the onset of absorption broadens and there is both an overall loss of resolution as well as a clear redistribution of spectral weight out of the lowest energy vibronic feature. The changes in absorption at 30OK are _₅ indicative of increased disorder, in many ways similar to the changes induced by the structural disorder of the spin-cast films.

Figure 6 demonstrates the anisotropy in the 8OK emission spectrum, L(ω) of an oriented free standing film of PE/MEH-PPV for parallel pumping. The inset displays the polarization dependence of L(ω) measured at the zero- phono line (2.091 eV) . The residual scattering sets a lower limit on this anisotropy of L(ω) parallel/L(ω) perpendicular greater than .60 with the preferred direction parallel to the draw axis. In addition to being much weaker, the L(ω) measured perpendicular shows relatively less spectral weight in the zero-phono line, consistent with a higher degree of disorder in the residual nonoriented material. for perpendicular pumping, the anisotropy (-30:1) and spectral features were similar, but with the intensity of the parallel emission reduced by about a,factor of four. To our knowledge, this is the first observation of truly anisotropic emission (magnitude and lineshape) in a conjugated polymer system.

In summary, we have demonstrated a novel method for obtaining highly aligned and structurally ordered conjugated polymers by mesoscale epitaxy using gel processing in blends with PE and subsequent tensile drawing. By controlling the concentration of conjugated polymer in the blend, we have obtained higher aligned, durable samples with controlled optical density. This allows the direct observation of the spectral changes that occur as a result of the improved structural order induced by mesoepitaxial alignment of the conjugated macromolecules. . The details of the spectral changes (sharper absorption edge and enhancement of the zero- phonon vibronic transition) imply a significant increase of the localization length. The photo-luminescence spectrum is polarized (>60:1) indicative of emission from ordered and aligned chains.

These results serve to confirm the importance of conjugated polymers as materials with potentially useful linear and nonlinear optical properties which result from the relatively broad energy bands and the strong ^ηt""κ interband transition which are characteristic of these semiconducting polymers. Patil, et al. The implied delocalization of the π*-electrons provides a mechanism for relatively high carrier mobilities upon doping or photoexcitation.

It was shown that the high degree of structural order achieved through gel-processing is transferred to the conjugated polymer in a UHMW-PE blend. This is surprising since the two component polymers are typically incompatible (since the entropy of mixing is necessarily small for macromolecules) . However, there is evidence of a strong interfacial interaction when conjugated polymers are added to a UHMW-PE gel; the frequency dependent conductivity results suggest that the conjugated polymer adsorbs onto the PE and decorates the complex surface of the gel network, thereby forming connected (conducting) pathways at volume fractions nearly three orders of magnitude below the threshold for three-dimensional percolation. The implied strong interfacial interaction suggests that gel-processing of conjugated polymers in PE may lead to orientation of the conjugated polymer component.

Example 17

Decalin (decahydronaphthalene, Aldrich) ; 9.7 g was mixed, at room temperature, with 200 mg of polydodecylthiophene in a 50 ml test tube. This stirred mixture was blanketed with nitrogen gas and heated to 104°C, at which time 200 mg of ultra-high molecular weight polyethylene (Hostalen GUR 415, Hoechst) was added. Subsequently, the mixture was heated to a temperature of 115°C, at which point stirring was stopped, and the temperature was raised further to 150°C for 1 hour. A viscous orange liquid was obtained. The solution was cooled, and the red-orange gel was transferred to a laboratory-scale spinning apparatus. A polyethylene/polydodecylthiophene gel fiber was spun according to standard procedures at 105°C in air.

This material is drawn in accord with the invention and exhibits the orientation properties observed in Example 16.

Example 18 The materials of Examples 15 - 17 are nonconducting. They are doped at 40°C in a 1.75%wt. solution of NOSbF_g or in iodine vapor (as representative methods) and found to be conductive.

Example 19

The accompanying figure, Figure 7, shows the anisotropic electroabsorption (electric field modulated absorption) of a film an oriented MEH-PPV/PE film containing a volume fraction of 6% MEH-PPV. At this concentration, direct optical absorption experiments are not possible for the optical density is too high. The electroabsorption was used, therefore, to characterize the orientation and alignment.

The film was prepared and then tensile drawn as described in the case of the 1% sample (Example 16). The spectra- shown in Figure 7 were obtained with a film drawn to 10 times its original length (draw ratio of 10) . The spectrum denoted by | was taken with the electric field parallel to the draw direction; the spectrum denoted by -¹ was taken with the electric field perpendicular to the draw direction. The results, demonstrate that the ME-PPV is oriented by the polyethylene.

Claims

WE CLAIM:

1. A shaped composite article having an electrical conductivity σ and a Young's modulus E, comprising:

(a) a substantially nonconducting, flexible- chain carrier polymer; and

(b) a conjugated, conducting polymer,

10 wherein the product of σ and E is at least about 0.3 (GPa) (S/cm) .

2. The composite article of claim 1, wherein the conjugated, conducting polymer represents at least

15 about 5 wt.% of the composite article.

3. The composite article of claim 1, wherein the carrier polymer is selected from the group consisting of polyethylene and polypropylene.

20

4. The composite article of claim 1, wherein said conjugated, conducting polymer is selected from the group consisting of poly(phenylenevinylene) , poly(2,5- dimethoxy-p-phenylenevinylene) and poly(2,5-

' thienylenevinylene) .

5. A solution-processed and drawn shaped composite article comprising an admixture of conjugated conductive polymer and a nonconductive flexible chain

30 carrier polymer the admixture exhibiting a combined modulus of at least about 0.5 GPa, and an electrical conductivity of at least about 10~⁷ S/cm. -

35

6. The solution-processed and drawn shaped composite article of claim 5 wherein said modulus is at_least 10 GPa, and said electrical conductivity is at least IO^-7 S/cm.

7. The solution-processed and drawn shaped composite article of claim 5 wherein said modulus is at least about 0.5 GPa, and said electrical conductivity is at least 10~³ S/cm.

8. The solution-processed and drawn shaped composite article of claim 5 comprised of a conjugated conductive polymer and a flexible carrier polymer of combined high modulus and electrical conductivity wherein said modulus is at least 10 GPa, and said electrical conductivity is at least 10^"3 S/cm.

9. A solution-processed and drawn composite article of claim 5 comprised of a conjugated conductive polymer and a flexible carrier polymer of combined modulus and high electrical conductivity wherein said modulus is at least about 0.5 GPa, and said electrical conductivity is at least 1 S/cm.

10. A solution-processed and drawn composite article of claim 5 comprised of a conjugated conductive polymer and a flexible carrier polymer of combined high modulus and high electrical conductivity wherein said modulus is at least 10 GPa, and said electrical conductivity is at least 1 S/cm.

11. The solution processed and drawn shaped composite article of claim 5 wherein the conjugated, conductive polymer represents at least 1 wt. % of the composite article.

12. The solution processed and drawn shaped composite article of claim 5 wherein the nonconductive flexible chain carrier polymer represents at least 5 wt. % of the composite article.

13. The composite article of claim 5 wherein the carrier polymer is selected from the group consisting of polyolefins and the vinyl polymers polyvinylalcohol, polyacrylonitrile, polystyrene, polyketone, polyamide and polyester.

14. The composite articles of claim 13 wherein the conjugated polymer is selected from the group consisting of poly(3-alkylthiophenes) , poly(phenylevinylene) and its derivatives, poly(thienylene vinylene) and its derivatives, and polyanilines.

15. A solution-processed and drawn composite article of claim 5 comprised of an admixture of conjugated conducting polymer and a flexible chain carrier polymer said admixture having a modulus at least about 0.5 GPa, and an optical dichroism of at least about 10.

0 16. The composite article of claim 15 wherein said modules is at least about 10 GPa.

17. The composite article of claim 15 wherein the conjugated, conducting polymer represents at least 1 ₅ wt. % of the composite article.

18. The composite article of claim 15 wherein the flexible chain carrier polymer represents at least 5 wt. % of the composite article.

20

19. The composite article of claim 15 wherein the carrier polymer is selected from the group consisting of polyolefins and the vinyl polymers polyvinylalcohol, polyacrylonitrile, polystyrene, polyketone, polyamide and __g polyester.

20. The composite articles of claim 19 wherein the conjugated polymer is selected from the group consisting of poly(3-alkylthiophenes) ,

₃_ poly(phenylevinylene) and its derivatives, poly(thienylene vinylene) and its derivatives, and polyanilines.

21. A process for making conjugated polymer shaped articles, the process comprising the steps of: (a) providing a carrier solution by dissolving in a compatible solvent:

(i) a predetermined amount of a conjugated polymer; and

(ii) at least about 0.1% v/v of a substantially nonconducting, flexible-chain carrier polymer;

(b) forming said carrier solution into the shape

10 of the desired shaped article;

(c) treating said carrier solution so as to cause gelation, thereby providing a carrier gel; and

(d) removing said solvent from the carrier gel.

-_g

22. The process of claim 21, wherein gelation is effected by coagulation with a nonsolvent for said carrier polymer.

23. The process of claim 21, further including

20 stretching said carrier gel at least about 100% in length prior to solvent removal.

24. The process of claim 21, further including rendering said shaped article conductive through p-type

25 (oxidative) or n-type (reductive) doping.

25. A process for making conjugated polymer shaped articles, the process comprising the steps of:

(a) providing a carrier solution by dissolving

30 in a compatible solvent:

(i) a predetermined amount of a precursor polymer selected to give a desired conjugated, polymer upon thermal or chemical treatment; and

35 (ii) at least about 0.1% v/v of a substantially nonconducting, flexible-chain carrier polymer; _g (b) forming said carrier solution into the shape of the desired shaped article;

(c) treating said carrier solution so as to cause gelation, thereby providing a carrier gel;

(d) converting said precursor polymer to said -₀ conjugated polymer; and

(e) removing said solvent from the carrier gel.

26. The process of claim 25, wherein gelation is effected by coagulation with a nonsolvent for said

_- carrier polymer.

27. The process of claim 25, further including stretching said carrier gel at least about 100% in length prior to solvent removal.

20

28. The process of claim 25, further including rendering said shaped article conductive through p-type (oxidative) or n-type (reductive) doping.

25 29. A process for forming an oriented conjugated polymer-containing shaped article comprising the steps of

(a) providing a carrier solution comprising (i) carrier solvent, (ii) nonconjugated flexible-chain

30 carrier polymer and (iii) conjugated polymer or conjugated polymer precursor;

(b) gelling and forming said carrier solution and removing solvent therefrom thereby yielding a body having a first shape; and

35 (c) anisotropically distorting the first shape of the body to yield the oriented conjugated polymer- containing shaped article characterized by anisotropic absorption and photoluminescence.

30. The process of claim 29 wherein in (c) the anisotropically distorting is accomplished by drawing.

0 31. The process of claim 30 wherein the drawing is to a draw ratio greater than 10.

32. The process of claim 30 wherein the drawing is to a draw ratio greater than 20. 5

33. The process of claim 29 wherein the carrier solution comprises

(i) carrier solvent,

(ii) from about 0.2% to about 60% by weight,

20 basis solvent, of carrier polymer, and

(iii) from about 0.2% to about 90% by weight, basis carrier polymer plus conjugated polymer, of conjugated polymer.

__g

34. The process of claim 29 wherein the carrier solution comprises

(i) carrier solvent,

(ii) from about 0.2% to about 10% by weight, basis solvent, of carrier polymer, and

30 (iii) from about 0.5% to about 25% by weight, basis carrier polymer plus conjugated polymer, of conjugated polymer.

35. The process of claim 29 wherein in step (b)

35 gelling occurs before forming.

36. The process of claim 29 wherein in step (b) gelling occurs after forming..

37. The process of claim 29 wherein the carrier polymer is ultra-high molecular weight polyethylene.

38. The process of claim 37 wherein the conjugated polymer is MEH-PPV.

39. The process of claim 37 wherein the conjugated polymer is a poly(3-alkylthiophene) .

40. The process of claim 37 wherein the conjugated polymer is poly(2,5-dimethoxy-p- phenylenevinylene.

41. The oriented conjugated polymer-containing shaped article characterized by anisotropic absorption and photoluminescence produced by the process of claim 29.