ON THE CONFORMATIONS OF POLY(P-XYLYLENE) AND ITS MESOPHASE TRANSITIONS

Molecular mechanics calculations for an isolated chain of poly(p-xylylene) have been carried out. The results have been used to model the transitions in the polymer that go from the crystal a to condis crystal β1 at (504 K), to condis crystal β2 (at 560 K), to the melt (at 700 K). Assuming increasing mobility in the phenylene groups of the trans conformational isomer, the two condis crystal forms could be modeled. It was not necessary to assume the presence of helical chain conformations. For the melt, additional planar chain and helical conformations are likely to account for the observed experimental entropies and enthalpies of transition. © 1990, American Chemical Society. All rights reserved.