PROCESSABLE POLYMERS AND COPOLYMERS OF 3-ALKYLTHIOPHENES AND THEIR BLENDS

Poly(3-alkylthiophenes) have been prepared using anhydrous FeCl3 in CHCl3 while dry air was bubbled through the reaction mixture. Molecular weight studies via GPC, using polystyrene standards in conjunction with RI and UV detection along with absolute determinations using a multiangle laser light scattering (MALLS) detector, have shown these materials are of high molecular weight (M(w) of up to 400,000) and relatively low polydispersity (M(w)/M(n) < 3). Further, the MALLS detector (absolute molecular weights) provides weight average molecular weights 2-5 times larger than those obtained using polystyrene standards showing that polystyrene is a rather poor standard for these materials. A series of copolymers of the 3-alkylthiophenes was prepared using a 1:1 molar feed ratio of the two monomers and the molecular weights of the materials decreased with decreasing side chain length. Poly(3-alkylthiophenes) were processable via a variety of methods, including melt spinning to form soft fibers. The films and fibers were dopable with typical oxidants to conductivities of up to 5 OMEGA-1 cm-1. The solution pulled fibers were observed to be birefringent with considerable orientation along the fiber axis. EDAX studies have shown that the doping of melt-spun fibers was quite uniform. Blends of poly(3-decylthiophene) with low density polyethylene have been prepared and melt-spun into fibers. Blends prepared by melt-blending the components were seen by electron microscopy to be phase separated into large domains while those prepared from xylene solution were much more uniform. Spinning was easier with the blends and the fibers spun from the blend prepared from xylene solution was seen to be birefringent with considerable orientation along the fiber axis. Doping of the melt spun fibers obtained from xylene solution formed blends gave conductivities of ca. 10(-1) - 1-OMEGA-1 cm-1 while those produced from the melt formed blends were non-conducting.