Transfer Reaction to Solvents in Free-Radical Polymerisation of Some Acrylate Monomers and Its Effect on Foam Density

One method of production of low-density polymeric foams is to dissolve a monomer and a photo-initiator in a solvent and to polymerise by means of free radical polymerisation. The gel produced is precipitated in a non-solvent and subsequent super critical drying produces a low-density micro-porous foam. In some cases, the observed densities of the foam were significantly higher than expected. There is evidence to believe that this could be due to a chain transfer reaction to the solvent used in polymerisation.