Spinodal decomposition driven microsegregation in polyacrylamide gels

We present small angle static light scattering measurements on unusually large pore polyacrylamide gels, grown in the presence of the preformed polymer polyethylene glycol. We show that the large pores of these gels are due to a microsegregation process, caused by the competition between gelation and segregation in the two-polymer solution, The presence of crosslinks prevents the system from undergoing a macroscopic phase separation which would otherwise occur via spinodal decomposition. The growth of the domains is eventually stopped by the gelation process and this process is ultimately responsible for the gel pore size.