Stereochemical and compositional assignments oftrans-4-methacryloyloxyazobenzene-methyl methacrylate copolymers by one- and two-dimensional NMR spectroscopy

Abstract

ABSTRACT:The microstructure of trans-4-methacryloyloxyazobenzene-methyl methacrylate copolymers prepared by solution polymerization process using AIBN as initiator is analyzed by one-and two-dimensional spectroscopy. Sequence distribution was calculated from the 13 C( 1 H)-NMR spectra of the copolymers. Comonomer reactivity ratios were determined using the Kelen-Tudos and the nonlinear error-in-variables methods are r A ϭ 1.14 Ϯ 0.08 and r M ϭ 0.51 Ϯ 0.03; r A ϭ 1.13 Ϯ 0.1 and r M ϭ 0.50 Ϯ 0.04, respectively. The sequence distribution of A-and M-centered triads determined from 13 C( 1 H)-NMR spectra of copolymer is in good agreement with triad concentration calculated from a statistical model. The 2-D heteronuclear single-quantum correlation and correlated spectroscopy (TOCSY) was used to analyze the complex 1 H-NMR spectrum.

Synthesis of Photoisomerizable Block Copolymers by Atom Transfer Radical Polymerization

“…After estimation with various monomer feed ratio at low conversion, the reactivity ratios for n-butyl methacrylate (r nBMA ¼ 0.9) and for trans-4-methacryloyloxyazobenzene (r MOAB ¼ 2.29) were obtained. MOAB showed a higher reactivity than nBMA during ARGET ATRP, which was in agreement with free radical copolymerizations, [45][46][47] as also observed in other systems. [48][49][50][51][52][53] Thus, a weak gradient structure was obtained within the copolymer chain.…”