Correlation Between the Physical Properties and Structure of Tetra-PEG Gels

Abstract

Tetra-PEG gel has drawn much attention as a polymer gel with extremely suppressed heterogeneity. Heterogene-ity is one of the intrinsic characteristics of polymer networks, and is difficult to control. Tetra-PEG gel is formed by a novel fabrication method, i.e., AB-type cross-end coupling, which is polycondensation between mutually reactive multi-armed polymers forming a polymer network. AB-type cross-end coupling has advantages on suppressing the heterogeneity over conventional polycondensation. The reaction achieved up to 90% of reaction conversion. The homogeneity of Tetra-PEG gel was confirmed by small angle neutron scattering; no excess scattering was observed in the range below 200 nm. The models of elastic modulus shift from the phantom network model to the affine network model with an increase in polymer volume fraction. The fracture energy was well predicted by the Lake-Thomas model. The ultimate elongation ratio was not predicted by the Kuhn model, but predicted by our semi-empirical model. These experimental studies suggested that Tetra-PEG gel has extremely homogeneous network structure and is a candidate material for evaluating the basic physical properties of polymer gels.