非等摩尔比聚电解质－两亲分子复合物及其结晶与堆砌结构变化

he structure of a series of non-equimolar linear poly(ethyleneimine)-octadecanoic acid complexes, lPEI-OA-x, with the molar ratio x of OA to the lPEI amino group ranging 0.66 ~ 1.45, was investigated with WAXD, SAXS, FTIR, DSC, and polarized optical microscope. Two crystalline modifications bO (b-orthorhombic) and bT (b-triclinic) of OA side chains have been found to coexist in the complexes varying with x and only 8 ~ 9 CH2 groups in an OA molecule participate in the crystallization. The complexes of x > 1.0 are predominant with bO form and stacked into an end-to-end bilayer lamella with the long period of ~5.6 nm. While for the complexes of x < 1.0, the bT form is dominantly stacked in the interdigitating monolayer structure with the long period of ~2.8 nm. Thermotropic liquid crystal state has been observed from the complexes of x < 1.0 above the melting point of the OA tail crystal. This study demonstrates that the crystalline and mesomorphous structures of polyelectrolyte-amphiphile complexes can be effectively tuned by changing the relative amount of bound amphiphiles.