2D NMR Studies of Poly(ethylene-co-vinyl acetate-co-carbon monoxide)

Abstract

A series of poly(ethylene-co-vinyl acetate-co-carbon monoxide) terpolymer samples with varying monomer compositions were studied using a variety of one-and two-dimensional nuclear magnetic resonance (NMR) techniques at 750 MHz. Samples were characterized in deuterated 1,4-dichlocrobenzene-d 4 at high temperature (120°C) to overcome the signal loss and broadening due to T 2 relaxation. Identification of major triads formed due to the addition of the three monomers in different permutations was facilitated by the use of different 2D techniques such as gradient assisted heteronuclear single-quantum correlation (gHSQC), gradient selected heteronuclear multiple-bond correlation (gHMBC), and gradient assisted HSQC-TOCSY. Detection of unusual structures formed due to the addition of carbon monoxide to vinyl acetate or structures due to the inversion of vinyl acetate was also possible. Because of improved dispersion the study was not restricted to the triad level, but in some cases pentads could also be identified. Distinct resonances of chain ends and short-chain branches were also observed.

Two-dimensional NMR studies of acrylate copolymers

“…It is difficult to resolve these complicated arrangements of repeating units along the polymer backbone. Rinaldi and coworkers studied the stereosequence of different triads in different copolymers and terpolymers by various 2D NMR techniques [73]. Composition analysis of butyl acrylate/methylmethacrylate/α-methyl styrene terpolymers was carried out by McManus et al [74] Thermogravimetric analysis (TGA) of acrylamide/acrylic acid/acrylonitrile terpolymers was performed by Rakshit and coworkers [75].…”

RETRACTED ARTICLE: Microstructure of poly(vinyl acetate)-block-poly(methyl acrylate-co-methyl methacrylate) block terpolymers. 2D NMR and thermal study

“…The effect of composition, sequence distribution and stereochemistry along the chemical bonds of copolymers was described in various papers [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] using two-dimensional HSQC, TOCSY, and HMBC NMR spectroscopy.…”

“…The effect of MMA composition on flexibility and glass transition temperatures of the copolymers were also reported. 25 750 MHz 1D and 2D NMR techniques were used to characterize poly(ethylene-co-vinyl acetate-co-carbon monoxide) 28 at high temperature (120 o C). Assignment of major triads was studied by 2D gradient HSQC, HMBC and assisted HSQC-TOCSY NMR.…”

“…1 ppm 28,32,38. The cross peaks centered at 39.1/1.60, 39.1/1.80, and 39.1/ 1.73 ppm in 2D HSQC NMR spectrum (Figure 5) are the characteristic peak of the non-equivalent protons VVmVV (H1) (49), VVmVV (H2) (50), and VVrVV…”

One- and two-dimensional NMR studies of methyl acrylate/vinyl acetate/N-vinyl carbazole terpolymers

“…Various coworkers [18][19][20][21][22] have investigated the microstructure of N-vinyl carbazole based copolymers with different monomers. The stereosequence of different triads in various carbazole copolymers and terpolymers have earlier been reported using various 2D NMR techniques [23][24][25][26][27].…”