Poly(n-alkyl acrylate) copolymer reactivity ratios were determined for n-alkyl acrylate monomers of various side-chain lengths n ranging from 6 to 22. Two sets of copolymers were synthesized to less than <10% conversion to evaluate the reactivity ratios. The first set included P(A10-co-A14), P(A10-co-A18), and P(A14-co-A18); while the second set consisted of P(A6-co-A12), P(A6-co-A22) and P(A12-co-A22). Copolymers were formed from monomer mixtures at 25 mol% intervals ranging from 0 through 100 mol%. C-13 NMR was performed on the homo polymers and the low conversion copolymers to determine the reactivity ratios of the monomers in each copolymer system. It was determined that the reactivity ratios for all monomers examined here were approximately equal to one. Physical properties of the copolymers, including melting point, heat of fusion, and permeation as a function of temperature, of the low conversion polymers were compared to copolymers formed at 100% conversion to demonstrate that these properties are independent of conversion because no composition drift occurs during polymerization. (C) 2004 Elsevier Ltd. All rights reserved.