Supramolecular polymer gels formed from carboxy-terminated telechelic polybutadiene and polyamidine through amidinium-carboxylate salt bridge

Abstract

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,N′‐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 three‐dimensional 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 Tgel of 37 °C. 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. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1815–1824

Dynamic cross-links to facilitate recyclable polybutadiene elastomer with excellent toughness and stretchability

“…In classical acid‐base reaction, the hydrogen bonds with proton transfer, which are termed as ionic hydrogen bonds, are usually formed between organic cations and anions . Recently, this type of reversible noncovalent interaction has been widely used to construct supramolecular polymers, due to its high stability and facile accessibility . The polymers based on ionic hydrogen bonding are also a type of ionomers because of the formation of ion pairs and have attracted considerable attention owing to their thermo‐reversible nature .…”

“…69,70 Recently, this type of reversible noncovalent interaction has been widely used to construct supramolecular polymers, due to its high stability and facile accessibility. [71][72][73][74][75][76][77][78] The polymers based on ionic hydrogen bonding are also a type of ionomers because of the formation of ion pairs and have attracted considerable attention owing to their thermo-reversible nature. [73][74][75][76] Endo and coworkers 75 reported the preparation of supramolecular polymer gels by mixing the ionomers of a carboxy-terminated telechelic PB and a linear polyamidine with N, N 0 -di-substituted acetamidine group in the main chain.…”

“…[71][72][73][74][75][76][77][78] The polymers based on ionic hydrogen bonding are also a type of ionomers because of the formation of ion pairs and have attracted considerable attention owing to their thermo-reversible nature. [73][74][75][76] Endo and coworkers 75 reported the preparation of supramolecular polymer gels by mixing the ionomers of a carboxy-terminated telechelic PB and a linear polyamidine with N, N 0 -di-substituted acetamidine group in the main chain. The rheology tests showed that the thermoreversible polymer gels underwent a gel-liquid transition at 37 8C due to the dissociation of the amidinium carboxylate ion pairs.…”

Preparation of recyclable polybutadiene rubber based on acid–base complexation

“…[29][30][31][32] Besides, chemicals with the acid and basic groups are abundant in nature and commercially available, enabling facile construction of supramolecular systems with versatile functions. Based on ionic hydrogen bonding, polymer gels [33][34][35][36] and block copolymers 37 with thermally responsive mechanical behavior have been demonstrated. Thus, it would be useful to incorporate thermoreversible ionic hydrogen bonds as alternative crosslinks into rubbers to achieve the reprocessing and recycling of crosslinked rubbers at elevated temperatures.…”

Supramolecular network polymers formed from polyamidine and carboxy‐terminated telechelic poly(n‐butyl acrylate) via amidinium‐carboxylate salt bridges

“…Supramolecular network polymers, which are the supramolecular analogue of covalently crosslinked network polymers, consist of individual polymer blocks crosslinked by noncovalent interactions, hence being defined as physical gels . A number of supramolecular network polymers have been designed and synthesized to date . Most of them are prepared from polymer chains that have randomly arrayed, noncovalent bonding units .…”