Preferential sorption of monomers and molecular weight effects in radical copolymerization

Specific thermodynamic properties of monomer mixtures as a solvent for copolymers lead to preferential sorption of one of the monomers by the polymer coils and preferential solvation of growing chains. The dependence of the preferential sorption coefficient upon the molecular weight of the copolymers results in the dependence of copolymer composition and monomer reactivity ratios upon the molecular weight of the copolymers and in gradient chemical heterogeneity of the copolymers. “Non-classical” copolymerizations can be represented by both terminal and penultimate models.