Enhancing and Tuning the Response of Environmentally Sensitive Hydrogels With Embedded and Interconnected Pore Networks

Abstract

Porous and temperature-sensitive poly(N-isopropylacrylamide) (PNIPAam) hydrogels with tunable and enhanced response properties were prepared by using porous poly(e-caprolactone) (PCL) molds. The molds were obtained from melt-processed cocontinuous polymer blends of ethylene propylene diene monomer (EPDM) and PCL. Quiescent annealing of the blends resulted in microstructure coarsening, and subsequent extraction of the EPDM phase yielded the molds. Ultimately, it allowed control over the average gel pore size from 20 to 300 μm. The gelling solution was injected within the molds, which were subsequently extracted, yielding hydrogels with fully interconnected pores. The porous gels display enhanced thermoresponsive properties in water: tunable, fully reversible and significantly faster swelling and deswelling responses following a temperature change across the PNIPAam lower critical solution temperature, as compared to nonporous gels. The fabrication process is compatible with a broad choice of gel chemistrie...