论文部分内容阅读
Polyolefins that bear a chiral side chain(typically an isobutyl group)experience a so-called macromolecularamplification of chirality:the chiral side-chain induces a slight preference for either tg or tg(?) main chain conformation.Thisslight conformational bias is amplified cooperatively along the chain,and results in preferred chirality of the main chainhelical conformations.As a result,these polymers display a liquid-crystal(LC)phase both in solution and,in the melt as atransient phase on the way to crystallization.The existence of two processes(melt-LC and LC-crystal transitions)results inunconventional behaviors that were first analyzed by Pino and collaborators back in 1975.These polymers also offer a meansto test the structural consequences of recently introduced crystallization schemes.These schemes postulate the formation of atransient liquid-crystal phase as a general scheme for polymer crystallization.
Polyolefins that bear a chiral side chain (typically an isobutyl group) experience a so-called macromolecularamplification of chirality: the chiral side-chain induces a slight preference for either tg or tg (?) Main chain conformation. Hisslight conformational bias is amplified cooperatively along the chain, and results in preferred chirality of the main chainhelical conformations.As a result, these polymers display a liquid-crystal (LC) phase both in solution and, in the melt as atientient phase on the way to crystallization. The existence of two processes (melt-LC and LC-crystal transitions) results in nonconventional behaviors that were first analyzed by Pino and collaborators back in 1975. These polymers also offer a mean test of the structural consequences of recently notified crystallization schemes. These schemes postulate the formation of atransient liquid -crystal phase as a general scheme for polymer crystallization.