Swelling and Diffusion Characteristics of Hydrogels Synthesized from Diepoxy-terminated Poly(ethylene glycol)s and Aliphatic Polyamines

Abstract

Hydrogels from diepoxy-terminated poly(ethylene glycol)s (PEG) of approximate molecular weights 600, 1,000, 2,000, and 4,000 Da and aliphatic polyamines with different numbers of amine hydrogen atoms (ethylene diamine, diethylenetriamine, triethylenetetramine, tris(2-aminoethyl)amine) in various combinations were synthesized and several means to adjust their water absorption were investigated. It was shown that the equilibrium swelling degree (ESD) can be tuned by varying the cross-linking agent functionality and molecular weight (MW) of the PEG precursor, by either employing single components or mixtures of polyamines or PEG oligomers. The ESD was also influenced by the reaction time and concentration of oligomer in feed. Further investigation of the swelling characteristics and water diffusion in the hydrogels synthesized revealed that the semicrystalline character of the xerogels, influenced mainly by the functionality of the cross-linking agent, PEG molecular weight, and degree of perfection of the network, was the main factor affecting the diffusion coefficient and transport mechanism.