Abstract: | Two series of acrylic acid-styrene copolymers of various composition have been prepared in benzene and dimethylformamide in order to study their sequence distribution by using 13C NMR spectroscopy. The reactivity ratios in benzene were rA = 0.13, rA = 0.30 and in dimethylformamide rA = 0.05, rS = 1.60. Copolymers with the same overall composition but prepared in different media display marked differences in sequence distribution, the copolymers obtained in dimethylformamide always having longer sequences. For the series of copolymers prepared in dimethylformamide, the experimental percentages of acrylic acid-centered triads (SAS, SAA, AAA) disagree with the values calculated from the monomer reactivity ratios. |