Cross-linker flexibility in porous crystalline polymers synthesized from long side-chain monomers through emulsion templating

Abstract

A polyHIPE is a cross-linked, highly porous polymer from the polymerization of monomers and cross-linking comonomers in the external phase of a high internal phase emulsion (HIPE). Crystallizable polyHIPE were synthesized through the copolymerization of stearyl acrylate (A18) with ethylene glycol dimethacrylate (EGDMA). PolyHIPE synthesized with the more flexible EGDMA were compared to those synthesized with the more rigid divinylbenzene. The polyHIPE densities were around 0.11 g cm⁻³. EGDMA destabilized the HIPE yielding relatively large voids and a structure whose partial closed-cell nature increased with increasing EGDMA content. The EGDMA cross-linked polyHIPE exhibited higher melting peak temperatures and higher crystallinities than the divinylbenzene cross-linked polyHIPE. Organic phase initiation of the EGDMA cross-linked polyHIPE yielded lower melting temperatures, lower crystallinities, and a highly interconnected porous structure that resulted in a lower modulus.