FORMATION AND RELATIVE REACTIVITY OF COMONOMER H-COMPLEXES IN THE RADICAL COPOLYMERIZATION OF ACRYLIC-ACID WITH 1-VINYL-2-PYRROLIDONE

The dimerization constant (K-d) of acrylic acid and the association co nstant of the comonomer complex between acrylic acid and 1-vinyl-2-pyr rolidone (K-1) have been determined in chloroform by means of IR and H -1 NMR spectroscopy: K-d = (2.0 +/- 0.2) x 10(3) litre mol(-1) and K-1 = 68.5 +/- 0.5 litre mol(-1). A detailed equation for the copolymer c omposition considering the participation of the intermolecular complex es in the chain propagation has been derived with the help of a specif ic regular three addition states Markov chain. Applying a numerical pr ocedure for fitting the experimental curve for the comonomer compositi on, this equation has been used in the estimation of the dimer and the comonomer complex relative reactivities. The considerably higher reac tivities of the two complexes compared with that of the monomers are a ccounted for by the pi-electrons' greater delocalization in the transi tion states involving the complexes species.