Solid State Morphology of Some Polypeptide Films

Plasticized and unplasticized films of poly-L-glutamic acid, poly-gamma-methyl-L-glutamate and poly-gamma-benzyl-L-glutamate were investigated by optical microscopy and X-ray diffraction. All of these synthetic polypeptides were cast from cholesteric liquid crystal solutions in a continuing investigation of a possible relation between liquid crystalline behavior in solution and solid state morphology. It was found in one case, PBLG plasticized with 35 vol % 3,3'-dimethylbiphenyl, that the Grandjean texture of the cholesteric mesophase was fully retained in solid films. In all other films no clear evidence of retention of cholesteric texture was found. However, it was found that PBLG cast from the liquid crustal mesophase had a very high degree of uniplanar orientation and a crystallographic net different from that found in films cast from racemic or magnetically oriented solutions. The latter are known to form a different, nematic mesophase. (Author) Prepared in cooperation with Bell Labs., Murray Hill, N. J.