Effect of prepolymer architecture on the network structure formed by AB-type crosslink-coupling

Abstract

An ideal polymer network free from any heterogeneity has been sought for decades to understand the molecular model for rubber elasticity. Recently, we developed a new crosslinking method, 'crosslink-coupling.' Unlike the conventional 'end-crosslinking' method, the crosslink-coupling method yielded an extremely homogeneous network; this result suggests that the prepolymer architecture is vital for the suppression of heterogeneity. The differences in prepolymer architecture between end-linking and crosslink-coupling are the 'sizes' and 'functionalities' of the prepolymers. In this study, we focus on the prepolymer size and investigate the mechanical properties of the polymer network formed from mutually reactive tetra-arm polyethylene glycol prepolymers with different sizes (size-mismatched Tetra-PEG gels). Our experiments revealed that the elastic modulus, the fracture energy and the ultimate elongation ratio of the size-mismatched Tetra-PEG gels had tendencies similar to those of conventional Tetra-PEG gels. From these results, we conclude that under these conditions, the size-mismatched Tetra-PEG gels have the same degree of homogeneity as the conventional Tetra-PEG gels, and the difference in prepolymer size does not affect the homogeneity. © 2014 The Society of Polymer Science, Japan (SPSJ) All rights reserved.