Epoxy networks and thermosensitive hydrogels prepared from α,ω-diamino terminated polyoxypropylene and polyoxyethylene bis(glycidyl ether)

A series of stoichiometric hydrophilic epoxy networks was prepared by reaction of α,ω-diamino terminated polyoxypropylene of average molar mass 430, 2000 and 4000 g mol^-1 with polyoxyethylene bis(glycidyl ether) of average molar mass 526 g mol^-1. The networks were investigated by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Single glass transitions observed in the networks strongly suggest that the networks present homogeneous single phase, i.e., polyoxypropylene (POP) and polyoxyethylene (POE) are homogeneously built in the network structure. The homogeneity of the networks is also confirmed by absence of a crystallization of POE. Hydrogels obtained by swelling of the networks in water exhibit a strong dependence of swelling degree on temperature. The temperature sensitivity of the hydrogels increases with growing molar mass of the POP used in the network preparation. The swelling behavior of the hydrogel containing POP of highest molar mass (4000 g mol^-1) is close to a discontinuity expected at a temperature ca 10-11 °C.