Atom Transfer Radical Copolymerization of Monomer and Cross-Linker under Highly Dilute Conditions

Abstract

The influence of dilution on the degree of intra- or intermolecular cross-linking reactions during the copolymerization of a monomer and a divinyl cross-linker via atom transfer radical polymerization (ATRP) technique was studied. To maximize intramolecular cross-linking, highly dilute systems with 0.5−10 vol % of monomer plus cross-linker vs solvent were used. The fraction of branched polymers formed through intermolecular consumption of pendant vinyl groups was calculated for each system through multipeak splitting of the gel permeation chromatography (GPC) curves. Progressive dilution of the reaction media resulted in the formation of products containing less branched polymers. Absolute molecular weights and compactness of the formed polymers determined by GPC with a multiangle laser light scattering (MALLS) detector further confirmed the formation of majority nonbranched polymer structures in more dilute systems, indicating an enhanced level of intramolecular cross-linking reactions in this case.