300-MHz Proton NMR and 25-MHz carbon-13 NMR investigations of sequence distributions in vinyl alcohol-vinyl acetate copolymers

Extent of intramolecular cyclization in RAFT-synthesized methacrylic branched copolymers using 13C NMR spectroscopy

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] For example, the extent of long-chain branching has been assessed during the free radical solution polymerization of n-butyl acrylate, vinyl acetate or 2-ethylhexyl acrylate. 2,10,14 Related studies conducted under emulsion polymerization conditions have implications for the grafting mechanism of polymeric stabilizers, which confer colloidal stability on the resulting latexes. More recently, this approach has been extended to include branching of n-butyl acrylate via living radical polymerization.…”

N,N-dicyclohexylcarbodiimide assisted synthesis and characterization of poly(vinyl alcohol-co-vinyl levulinate)

“…These three signals, therefore, can be assignable to the three compositional dyads of (VA,VA), (VA,VL) and (VL,VL) in order of decreasing frequency, where VA, and VL denote vinyl alcohol unit and vinyl levulinate unit, respectively. The chemical shift dependence on the degree of esterification is very much similar to those of vinyl alcohol-vinyl acetate copolymers [47,48,[51][52][53][54][55] and vinyl alcohol-vinyl propionate copolymers [56].…”

“…1 shows the 1 H NMR spectra of a sample of VA-VL copolymer, LA and PVA together with the assignment of signals in the copolymer. The copolymer provides not only the signals due to the feature of the original PVA backbone structure [47][48][49] but also the signals due to levulinate group. The signals at 2.10 ppm and a set of 2.43 and 2.69 ppm in the spectrum of the copolymer are attributable to the methyl and two methylene protons of levulinate unit [50], respectively.…”

“…The broad multiplet signal at the region from 1.2 to 1.9 ppm is due to methylene protons in the copolymer backbone. The multiplet signals centered at 3.76 ppm and at 5.02 ppm are assignable to two kinds of methine protons bearing hydroxyl groups and the levulinate units in the backbone, respectively [47][48][49].…”

Stereochemistry of vinyl polymers and NMR characterization

“…Since this copolymer was made by base hydrolysis of poly(viny1 acetate), the hydrolysis must not have been a random (Bernoullian) process. 27 The rather extreme probability values (a = Pa = 0.719, and 1 -6 = PBBB = 0.917) suggest that neighboring alcohol groups greatly facilitate the hydrolysis of the acetate.…”