Li Liangbin, de Jeu Wim H
FOM-Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
Phys Rev Lett. 2004 Feb 20;92(7):075506. doi: 10.1103/PhysRevLett.92.075506.
We report an unusual shear-induced smectic phase of high-molecular-mass isotactic polypropylene at temperatures well above its melting point. The necessary stiffness in the polymer chain is provided by shear-induced coil-helix transitions. Coupling between the conformational ordering and the density generates the smectic layering. The periodicity of about 4 nm is built up from a rigid helical sequence of at least 11 monomers and a random-coil part of about 1.4 nm. These results also provide new clues to the question of preordering before polymer crystallization.
我们报道了一种高分子质量全同立构聚丙烯在远高于其熔点的温度下由剪切诱导产生的不寻常近晶相。聚合物链中必要的刚性由剪切诱导的线团-螺旋转变提供。构象有序性和密度之间的耦合产生了近晶层状结构。约4纳米的周期性由至少11个单体的刚性螺旋序列和约1.4纳米的无规线团部分构成。这些结果也为聚合物结晶前的预有序问题提供了新线索。
