Supramolecular Polymer Gels Formed from Carboxy-Terminated Telechelic Polybutadiene and Polyamidine through Amidinium-Carboxylate Salt Bridge

摘要

In this article, we report the preparation and properties of the bulk supramolecular polymer gels prepared from a polybutadiene based on the amidinium-carboxylate salt bridge, highlighting the difference from a well-established network system based on carboxylic acid and amine. We have prepared the amidinium-carboxylate salt bridge-based supramolecular polymer gels from a carboxy-terminated telechelic polybutadiene and a linear polyamidine having N,N0-di-substituted acetamidine group in the main chain. FTIR analysis along with Small angle X-ray scattering measurements indicated that the salt bridge was attributed to the gelation through threedimensional network formation. Virtually no fluidity was observed for the supramolecular gel containing equimolar amounts of the carboxyl group and the amidine group, which showed a high G' value of about 1 MPa at room temperature and a T_(gel) of 37℃. For comparison, the supramolecular polymer gels crosslinked by ammonium-carboxylate salt were prepared using a linear polyethyleneimine instead of the polyamidine. The gel with equimolar amounts of the carboxyl group and the secondary amino group showed liquid-like fluidity with a G' value of about 0.01 MPa at room temperature, which was attributed to the fact that a certain amount of the carboxyl group remained as its free form without salt formation, as evidenced by FTIR analysis.