1H‐NMR study of structure and tacticity in p‐t‐butylstyrene/methyl methacrylate copolymers

Abstract Copolymers prepared by the bulk copolymerization of p‐t‐butylstyrene (S) and methyl methacrylate (M) were analyzed by 1H‐NMR. The spectra showed fine structure in the δ 2.2–3.6 region similar to that reported for styrene/methyl methacrylate copolymers. Reactivity ratios for S‐M copolymers determined by classical composition measurements differed markedly from the same ratios determined by NMR when it was assumed that NMR peak‐triad assignments could be made by analogy with published styrene/methyl methacrylate assignments. A new set of peak‐triad assignments was proposed that reconciles this difficulty and gives good agreement between triad fractions measured by NMR and those calculated from theory.