Synthesis and characterization of porous glycidylmethacrylate-divinylbenzene monoliths using the high internal phase emulsion approach

Highly porous monoliths were synthesised using glycidyl methacrylate (GMA) and divinylbenzene in the presence of a porogen, and emulsion templating as the preparation technique (polyHIPEs). Two surfactants were used as the emulsion stabiliser. It turned out that the choice of the surfactant was essential for the successful synthesis of polyHIPEs containing large amount of the functional monomer GMA, and characterised by a well-defined morphology. Sorbitan monooleate (SPAN 80) showed poor performances in stabilising emulsions with a content of GMA > 40% v/v. On the contrary, polyglycerol of a fatty acid (PGE 080/D) exhibited superior performances allowing to stabilise emulsion with a GMA content up to 80% v/v. The ensuing polyHIPEs presented a well-defined morphology and surface areas very close to those of the corresponding resins of the same composition. This proved that emulsion destabilising phenomenon such as Ostwald ripening was effectively inhibited by PGE. An important part of the research work was dedicated to investigate whether the epoxy group retained its integrity during synthesis and purification. It turned out that the percentage of the exposed epoxy groups that underwent hydrolysis depended on the size of the pores. Pores below a threshold size were not wetted by water and the epoxy groups present inside them were left unchanged. On the contrary, the epoxy groups within pores characterised by a diameter above this threshold underwent hydrolysis.