ИСТИНА

Polymethyledenephtalide (PMPh) is a cardopolymer in which the side cyclic phtalide groups in its macromolcules with the most probable "head to tail" configuration are separated only by one methylene bridge. Such a high concentration of the phthalide substituents along the polymer chain leads to considarable steric interactions, which in turn manifest themselves in a certain level of the main chain stereoregularity depending on radical polymerization conditions of methyledenephtalide. The stereochemical structure of PMPh was established by means of NMR spectroscopy on 1H and 13C nuclei using two-dimensional correlation techniques COSY , TOCSY, NOESY, DOSY, editing - HSQC, and HMBC. Also the full assignment of the observed signals with a respect to stereochemistry was made. It was shown that the radical bulk polymerization initiated by peroxides results in formation of a polymer enriched by syndio - triads. The introduction into the reaction medium solvents of different nature affects the stereoregularity of the resulting polymer. Thus, PMPh obtained in cyclohexanone is an atactic polymer whereas in less polar m-cresol an isotactic structure is realized. PMPh synthesized in bulk and cyclohexanone or m-cresol solutions is able to crystallize partially forming ordered regions of very small sizes judging from the half-width of the crystalline peaks in X-ray diffractograms. The dependence of the crystalline structure on the content of syndio- or iso- triads in the polymer, as well as on samples history was observed. The glass transition temperature of PMPh is 295oC, and the melting temperature of the crystalline phase is above its decomposition temperature (320oC).