Characterization of High Molecular Weight Acrylamide-Based Copolymers by DOSY-NMR Using High Field-Gradients

Copolymers of [ 2 -( acryloyloxy ) ethyl ] trimethylammonium chloride ( AETAC ) and acrylamide ( AAm ) having weight - average molecular weights ( M w ’ s ) exceeding 10 million were analyzed by di ff usion - ordered two - dimensional spectroscopy ( DOSY ) using high fi eld - gradients ( ≤ 13T / m ) . Distribution curves of the self - di ff usion coe ffi cient D ) were successfully obtained for the copolymers, and the D values at the peak top ( D p ’ s ) correlated well with M w as D p = ( 1.86 × 10 ¹ 8 ) × M w – 0.749 . The distributions of D agreed fairly well with those determined by dynamic light scattering. The DOSYanalysis revealed the molecular weight dependence of the chemical composition of the copolymers; the relative AETAC content increased with decreasing molecular weight.