POLYMER BLENDS BY SELF-PROPAGATING FRONTAL POLYMERIZATION

The use of self-propagating frontal polymerization to produce polymer blends has been investigated. A homogeneous solution of monomer, polym er (of a second monomer), and initiator is initially heated at a speci fic location to start a polymerization front that propagates along the system. The obtained polymerization reaction is very fast compared wi th diffusion, sea that the two types of macromolecules remain homogene ously distributed, as in the original monomer/polymer solution. In the case of two incompatible polymers, the system has no time to reach th e equilibrium condition where phase separation occurs and a polymer bl end is obtained in the form of a metastable solution. Applications to two incompatible pairs (methyl methacrylate-styrene and methyl methacr ylate-methacrylic acid) are discussed. Moreover, it has been found tha t the presence of inert polymer in the initial mixture improves the pr ocess performance, leading to more stable propagation fronts, lower fr ont temperatures, and higher monomer conversions. (C) 1998 John Wiley & Sons, Inc.