Aliphatic polycarbonate-based polyurethane elastomers and nanocomposites. I. the influence of hard-segment content and macrodiol-constitution on bottom-up self-assembly

Abstract

Aliphatic polycarbonate-based polyurethane (PC-PU) elastomers as well as their nanocomposites with organic-modified clay (bentonite for organic system) were synthesized. Macrodiols (MD) (randomly copolymerized aliphatic PC-glycols of molecular weight of about 2000: T5652, T4672, and T4692), hexamethylene diisocyanate, and butane-1,4-diol were used as starting materials. Solid-state NMR and Fourier transform infrared spectroscopy, small-angle X-ray scattering, wide-angle X-ray diffraction, atomic force microscopy, and transmission electron microscopy were used for studying the bottom-up self-assembly of building units from the segmental level up that of organized structures of micrometer sizes. Contents of hard segments formed by the reaction of chain extender with diisocyanate plays a dominant role for the degree of ordering and related phenomena, while the MD chain has only limited effect on PC-PU properties. The spectroscopy and scattering experiments suggest that bentonite particles incorporate well in the structure and promote the ordering of hard segment domains in PC-PU matrix as compared with the nanofiller-free analogue. © 2012 Wiley Periodicals, Inc.