NMR study of poly(vinyl chloride)-β,β-d2 |
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Authors: | L Cavalli G C Borsini G Carraro G Confalonieri |
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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. |
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