Proton and Carbon-13 Nuclear Magnetic Resonance Studies of Poly(vinyl alcohol)

Abstract

Proton resonance spectra (220 MHz) and carbon-13 Fourier transform noise-decoupled spectra (22.6 MHz) of poly(vinyl alcohol) (PVA) were obtained. By examining the hydroxyl proton spectra in dimethyl sulfoxide solution, we have deduced triad tacticity of PVA. Moreover, the stereochemical sequence distributions in terms of triads and tetrads were determined from the methine and methylene carbon spectra, respectively. It was found that stereoregularity of radical-initiated polymerization of vinyl acetate is independent of the polymerization conditions but can be described by Bernoullian statistics.

The synthesis of poly(vinyl cinnamates) and its self‐assembled structure

“…Signal at 3.80 ppm can be assigned to a methine proton in polymer chains. The resonance signals of the methylene protons are observed at 1.20–1.60 ppm [23, 24]. Figure 2b presents the multiplet signals at 7.38–7.70 ppm are due to aromatic protons of cinnamate units.…”

Influence of degree of crystallinity and syndiotacticity on infrared spectra of solid PVA

“…The equation [η] = 8.91 × 10 −3 DP 0.62 was used 19. The triad contents were determined from the intensities of the methine carbon of 125 MHz 13 C‐NMR spectra taken at 80°C in DMSO‐ d 6 using a Brucker‐DRX‐500 NMR spectrometer 20. The s ‐(diad) % was estimated as s ‐(diad) % = S + (1/2) H ( S : syndiotactic triad percent; H : heterotactic triad percent) with the assumption of a simple Markofian process for polymerization.…”

Self‐association through hydrogen bonding and sequence distribution in poly(vinyl acetate‐co‐vinyl alcohol) copolymers

“…The main features of the 13 C NMR spectra for ACA copolymer have been described elsewhere. [7][8][9][10][11] The most interesting region of the sequence distribution is that of the methylene re-gion. Figure 1 shows the 13 C NMR spectra of the methylene region (38 -46 ppm) for three ACA copolymers (A, B, and C) with different degrees of hydrolysis by saponification, but the starting materials PVAC prepared by solution polymerization.…”

“…They have been assigned as rrr, rrmϩmrm, mmrϩrmr, and mmm with increasing field strength according to similar absorption peaks reported by Wu and coworkers. 11,12 The methine carbon resonances pre-viously described were preferred for tacticity estimations, because they are gradually better separated from each other.…”