Epoxy networks and hydrogels prepared from alpha,omega-diamino terminated poly(oxypropylene)-b-poly(oxyethylene)-b-poly(oxypropylene) and polyoxypropylene bis(glycidyl ether)
Abstract
A series of hydrophilic epoxy networks was prepared by reaction of alpha,omega-diamino terminated polyoxypropylene-b-polyoxyethylene-b-polyoxypropylene of average molar mass 2000 g mol(-1) with polyoxypropylene bis(glycidyl ether) of average molar mass 640 g mol(-1) Absence of microphase separation in the networks at ambient and higher temperatures was proved by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Cooling of the networks to subambient temperatures induces microphase separation via crystallization: the crystallites of polyoxyethylene formed act as a reinforcing filler in the surrounding amorphous network phase.
Hydrogels obtained by swelling of the networks in water deswell continuously with increasing temperature. The deswelling becomes less pronounced with increasing POE content and decreasing network density of the epoxy network.
In cooling of the hydrogels to low temperatures the main part of water crystallizes. Water crystallites are dispersed in the amorphous network swollen with remaining no-crystallized water.
The hydrogels prepared can found applications in sensors and actuators working in aqueous environment.