Liquid crystallinity of concentrated solutions of polymacromonomers consisting of polystyrene

The liquid crystallinity of concentrated solutions of polymacromonomer (SS- 33) samples consisting only of polystyrene with a fixed side chain length o f 33 styrene residues was examined using various solvents for polystyrene. Toluene, carbon tetrachloride, and ethylene dichloride solutions of the sam ples lost the fluidity to form physical gels before forming liquid crystal phases, when the polymer concentration was increased. On the other hand, co ncentrated dichloromethane (DCM) and chloroform solutions of SS-33 exhibite d birefringence to form a nematic phase. The phase boundary concentration c (I), where SS-33 solutions start showing birefringence, was determined for DCM solutions as a function of the polymer molecular weight. The results we re rather close to the prediction from the scaled particle theory with the wormlike-chain parameters estimated from dilute solutions studies. However, the experimental molecular weight dependence of c(I) was appreciably stron ger than theoretically predicted, and some problems of the scaled particle theory, originally proposed for linear stiff-polymer solutions, were pointe d out.