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Molecular asymmetry r e q u i r e s a h i g h conformational energy b a r r i e r f o r the polymer backbone. and an asymmetric i n i t i a t o r t o induce a predominance o f one h e l i c a l screw-sense. P o l y c h l o r a l meets t h e c r i t e r i a . Asymmetric i n i t i a t o r s used t o o b t a i n o p t i c a l l y a c t i v e p o l yc h l o r a l include tetramethylammonium (+)-o r (-1-0-acetylmandelate. tetramethylammonium (+)-o r (-)-0-methylmandelater t h e l i t h i u m a l k o x i d e s o f methyl (+)-o r (-)-mandelater l i t h i u m cholesten-36-oxide, l i t h i u m cholestan-36-oxide. and l i t h i u m (+Io r (-)-2-octanoxide. Using the above i n i t i a t o r s a t 0.5 mot %.

Samples of chloral homopolymers and copolymers with aromatic isocyanates of high chloral content were prepared by cryotachensic polymerization as films of 0.1 to 5 mm thickness. Thermal, mechanical, and electrical properties of these polymers were measured. Polychloral is unlike most other linear polymers as it does not show any melting or glass transition below 220°C, at which temperature the polymer starts to degrade by depolymerization to monomer. The polymer is of moderate crystallinity and shows properties characteristic of engineering plastics.

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