NMR study of poly(vinyl chloride)‐β,β‐d₂

Abstract

The high‐resolution NMR spectra at 60 and 100 Mcps of poly(vinyl chloride)‐β,β‐d2 in o‐dichlorobenzene, pyridine, and C2HCl5 solutions are reported. The use of low molecular weight samples and of {D} spin‐decoupling experiments, which yield higher resolution spectra, results in the observation of a number of additional resonances for the α‐proton. These can be interpreted in terms of pentad configurational sequences of monomer units. It is found that, whereas the S syndiotactic pentads cannot be resolved, two components of the H heterotactic and all of the possible I isotactic pentads are clearly discernible. From the tacticity values of polymers prepared at +40, 0, and −40°C, enthalpy and entropy of activation for isotactic and syndiotactic monomer placement are found to be 630 cal/mole and 1.5 eu, respectively.

DFT Calculations Suggest a New Type of Self‐Protection and Self‐Inhibition Mechanism in the Mammalian Heme Enzyme Myeloperoxidase: Nucleophilic Addition of a Functional Water rather than One‐Electron Reduction

“…Therefore, this polymerization proceeds, most probably, by a combination of competitive pathways that involves activation via SET mediated by nascent Cu 0 both in the initiation and propagation steps and by degenerative chain transfer (Scheme ). The resulting PVC obtained in water at 25 °C is free of structural defects, contains two active ∼CHClI chain ends, and has a higher syndiotacticity (62%) than the one obtained by free‐radical polymerization at the same temperature (56%) 57, 82–84. The synthetic process for the LRP of VC here will allow for the time access to the synthesis of PVC with a complex architecture85–88 and unprecedented properties.…”

NMR Determination of the Microstructure of Poly(vinyl chloride sulfone). I. 1H Spectra

“…The high-field resonance area (5.0-4.2 ppm) can be assigned to VV diads (arising from VV*S and SVV* triads and longer VC blocks with the methine proton situated from SO2, by comparison with the spectrum of poly(vinyl-/?,d-d2 chloride)). 33 The asterisk indicates the monomer unit in which the proton under observation is located, a, ß, etc., refers to the proximity of the carbon atom, to which the methine proton is bonded, to the S atom, as shown in Table II, and V represents a vinyl chloride unit in the direction -CHCI-CH2-. The low-field resonance area (6.2-5.4 ppm) is then assigned to SV diads, i.e., -sulfonyl methine protons, which will comprise SVS, The VV diad resonance area in Figure 2A can be further divided into two major peaks (5.0-4.6 and 4.6-4.2 ppm).…”

A study of methods for measuring the tacticity of poly(vinyl chloride) by proton magnetic resonance spectroscopy

“…Consider first the results for the four commercial polymers (2)(3)(4)(5), and as the values in the four individual vertical columns have already been noted and considered briefly above it is instructive to examine the spread of the means of the four columns, which is 0,063. 7.…”