Vinyl pyrrolidone-methacrylic monomers bearing salicylic acid derivative moieties: copolymerization parameters and microstructure analysis

Copolymers of vinyl pyrrolidone (VP) and the methacrylic monomers derived f rom salicylic acid, 2-hydroxy-4-methacrylamidobenzoic acid (4HMA) and 2-hyd roxy-5-methacrylamidobenzoic acid (5HMA), were prepared by free radical pnl ymerization in DMF solution at 50 degrees C, using 2,2'-azobisisobutyronitr ile (AIBN) as initiator. The reactivity ratios of the monomers were calcula ted according to the general equation using the Fineman-Ross and Kelen-Tudo s linearization methods, and also the Tidwell and Mortimer nonlinear least- squares treatment. The most probable reactivity ratio values derived from t he 95% confidence diagram were the Tidwell and Mortimer ones giving r(4HMA) = 6.59 and r(VP) = 0.03 for the 4HMA-VP system, and r(5HMA) = 10.58 and r( VP) = 0.02 for the 5HMA-VP copolymer. The micro-structure of the copolymer chains was analysed according to a first-order Markov statistic and to the Skeist equation for the dependence of the composition on the conversion deg ree. (C) 2000 Elsevier Science Ltd. All rights reserved.