Robust, highly porous hydrogels templated within emulsions stabilized using a reactive, crosslinking triblock copolymer

Abstract

PolyHIPEs (PHs) are porous polymers that are typically templated within surfactant-stabilized high internal phase emulsions (HIPEs). Hydrogel PHs (HG-PHs) have exhibited potential as absorbents, adsorbents, release systems, and tissue engineering scaffolds. Recent work has shown that HG-PHs with highly temperature sensitive water uptakes could be produced using a reactive block copolymer (BC) as the sole surfactant, monomer, and crosslinker. It is not clear, however, whether these properties could be transferred to a HG-PH based on conventional hydrogel monomers and synthesized within a HIPE stabilized using a reactive BC. This work investigates HG-PHs based on acrylamide (AAm) synthesized within a HIPE stabilized by F-127-DMA, a reactive crosslinking BC based on methacrylate endcapped Pluronic F-127 (a commercial PEO-PPO-PEO triblock copolymer with poly(ethylene oxide) (PEO) endblocks and a poly(propylene oxide) (PPO) midblock). All the F-127-DMA-containing HG-PHs exhibited highly interconnected porous structures, low densities, and robust compressive behaviors with no chalkiness. The combination of F-127-DMA crosslinking and emulsion templating produced amplified and accelerated water uptakes, up to 161 g/g, associated with hydrogel-swelling-driven void expansion, and enhanced the temperature sensitivity, with the uptake decreasing by ∼50% between 5 and 60 °C, compared to reference HG-PHs and to conventional hydrogels.