Fabrication of porous polyurethane monoliths on strengthening interface of concentrated emulsion polymerization

A method for preparing porous polyurethane (PU) monoliths through a step polymerization in concentrated emulsion template was proposed. The concentrated emulsion was constructed by using tolylene diisocyanate (TDI), butylenes glycol and a surfactant as the continuous phase, and deionized water as the dispersed phase. Polyglycerol polyricinoleate (PGPR) was selected as the surfactant because it was an amphiphilic oligomer containing reactive hydroxyl groups. It could react with TDI firstly and thus built up a solid interface to maintain the stability of the concentrated emulsion. As a result, polyurethane porous monolith was obtained by the curing reaction between TDI and OH containing species and thereafter the removal of water phase. When colloidal silica particles were introduced into aqueous phase, a more uniform and finer porous structure could be achieved from the more strengthened interface. The effects of the composition, the surfactant, the volume fraction of dispersed phase, and the content of colloidal silica on the morphology of porous PU were investigated. (C) 2015 Elsevier B.V. All rights reserved.