CHARACTERIZATION OF THE STEREOCHEMICAL STRUCTURE OF POLY(ACRYLIC ACID) BY ONE-DIMENSIONAL AND 2-DIMENSIONAL C-13-H-1 NUCLEAR-MAGNETIC-RESONANCE SPECTRA

The stereochemical structure of two samples of poly(acrylic acid) (PAA ) of different tacticities was studied by a combination of one- and tw o-dimensional (2D) C-13-H-1 nuclear magnetic resonance (n.m.r.) spectr a. Lines in C-13 n.m.r. spectra of PAA solutions in D2O could be assig ned to configurational triads (CH region) and hexads or hexad pairs (C H2 region). For analysis of the CH2 region, the application of the inv erse HETCOR (heteronuclear correlation) (i.e. heteronuclear multiple-q uantum coherence, HMQC) 2D C-13-H-1 n.m.r method was essential. Both f or CH and for CH2 carbon resonances our assignment differs from those previously published in the literature. The studied PAA samples prepar ed by radical polymerization or by hydrolysis of poly(t-butyl acrylate ) obtained by anionic polymerization obey Bernoullian statistics.