Tough reinforced open porous polymer foams via concentrated emulsion templating

Low-density but very resilient and robust polymer foams possessing an interconnected open porous network have been synthesised by the polymerisation of the continuous phase of concentrated or high internal phase emulsions containing polyethylene glycol dimethacrylate (PEGDMA) as main crosslinker. The synthesised polymer foams did not display the undesirable properties, such as brittleness and chalkiness, which are commonly observed for highly crosslinked porous polymer monoliths synthesised by the polymerisation of high internal phase emulsions. An effective way to improve the mechanical performance of open porous polymer foams is to raise the apparent foam density. Therefore, the continuous phase of the emulsions was increased up to 40 vol.%. The mechanical properties can be further increased by the incorporation of silica particles into the polymer. Methacryloxypropyltrimethoxysilane was added to the continuous phase to ensure that the silica particles were covalently bonded into the inorganic polymer network formed by the hydrolytic condensation of the silane groups. The addition of reinforcement increased the mechanical properties. The Young's modulus and the crush strength of the polymer foams increased by up to 360% and by up to 300%, respectively, in comparison to non-reinforced samples.