Gelation kinetics and polymer network dynamics of homogeneous tetra-PEG gels

Abstract

Tetra-PEG gels made via cross-end-coupling of tetra-arm poly(ethylene glycol) chains having complementary functional groups have been recognized to have a very homogeneous network structure free from inhomogeneities and entanglements. Their unique network structure provides advanced mechanical properties, such as high deformability and toughness. The origin of these unique structure and properties is investigated from the viewpoints of gelation kinetics and polymer network dynamics. Spectroscopic studies on gelation kinetics of Tetra-PEG gels indicate that the gelation kinetics is classified to reaction-limited process, leading to formation of uniform polymer network with high yield. Polymer dynamics studied with neutron spin echo (NSE) and dynamic light scattering (DLS) shows that the dynamic is classified to Zimm mode in the microscopig regime (NSE window), and to collective diffusion mode in mesoscopic regime (DLS window). The crossover was found to correspond to the mesh size of the network. The absence of the offset in the intermediate scattering function also indicates homogeneity and uniformity of Tetra-PEG gel networks.