Characterization of Styrene–Vinyl Alcohol Copolymers by CP-MAS NMR Spectroscopy

Abstract

The first solid-state characterization of statistical copolymers of vinyl alcohol and styrene (poly(VA-stat-St)) by cross-polarization magic angle spinning (CP-MAS) spectroscopy is described. Poly(VA-stat-St) is not available from the traditional feedstocks styrene (St) and vinyl acetate (VAc) due to a mismatch in reactivity ratios. BN 2-vinylnaphthalene (BN2VN) is a synthetic solution to this challenge as it copolymerizes with activated monomers (e.g., styrene, methyl methacrylate), and the BN naphthalene side chain can be oxidatively converted to hydroxyl (−OH) side chains. While high levels of BN2VN incorporation are readily achieved (e.g., >75 mol % BN2VN), prior work has identified that poly(VA-stat-St) is poorly soluble in organic solvents when the molar fraction of VA exceeds 0.50, presumably due to the hydrophilic character of the hydroxyl group as well as possible interchain hydrogen bonding. Circumventing this solubility challenge, we describe quantitative solid-state 13 C CP-MAS spectra demonstrating high conversion (85−99%) of poly(BN2VN-stat-St) to poly(VA-stat-St). 11 B CP-MAS confirmed the removal of organoborane functional groups.

RAFT polymerization of an aromatic organoborane for block copolymer synthesis

“…5a), which was previously found to provide conversions up to 99% in styrene-BN2VN statistical copolymers. 44…”

“…5a), which was previously found to provide conversions up to 99% in styrene-BN2VN statistical copolymers. 44 Oxidation had a significant effect on the physical properties of the samples. While RS 48 and RS-b-RB are yellow due to the absorbance of the TTC end group and/or BN naphthalene side chain, the oxidized samples were white (Fig.…”

Precise Characterization of the Sequence Distribution of Poly(vinyl butyral) (PVB) by 2D-NMR and Isotope Enrichment

“…Numerous efforts have been attempted to clarify the detailed microstructure of the synthetic polymers, i.e., the Kerr effect, , mass spectrometry, − and nuclear magnetic resonance (NMR). − Among them, NMR stands out as the main analytical technique to quantify the detailed microstructure of synthetic polymers. Because the majority of the synthetic polymers are carbon-based materials, the NMR active 13 C spin is frequently used.…”

NMR spectroscopy based configurational and compositional analysis of isobornyl methacrylate—Acrylonitrile copolymers

“…Various researchers have used 1D and 2D NMR spectroscopy to report on the microstructure of copolymers of acrylonitrile with alkyl acrylates [18][19][20][21] . Copolymers of acrylonitrile have also been synthesized by various techniques [22][23][24][25] using different starting compositions at different temperatures and pressures.…”