Order in Nematic Phase of Semiflexible Polymers

Abstract

Orientational order in the nematic phase of the thermotropic aromatic polyester (C10H20OC6H4COOC6H4OC10H20OC6H4OOCC6H4O)I has been evaluated from magnetic susceptibility measurements and has been compared with those for the corresponding monomer and dimer, i.e., C6HnO-C6H4COOC6H4OCBH11 and, respectively. The (orientational) order parameter of this polymer near the isotropic-nematic transition is found to be ca. 0.6, compared to the corresponding order parameters of ca. 0.4 for the monomer and ca. 0.5 for the dimer. These results are thus confirmatory of the recent theory of Ronca and Yoon, which predicts that the isotropic-nematic phase transition of semiflexible polymers does not entail a very high degree of order in the resultant nematic phase and that this nematic phase should become a thermodynamically viable state for polymers with limited flexibility. This finding is contrary to the ideas of polymer crystallization or glass transition advocated on the physical impossibility of random chains with limited flexibility to fill the space. © 1983, American Chemical Society. All rights reserved.