Synthesis And Characterization Of Cyclic Polymer

Since the cyclic macromolecule DNAwas found, the cyclic polymer which have not the endgroups has been an interesting research topic. Due to the structural units of the chain arechemically and physically equivalent, it results in diverse novel unique polymer properties, andarouses a lot of widespread interest. The current preparing methods of cyclic polymer are theintramolecular cyclization of the telechelic polymer under the conditions of dilute solution. As aresult of the existence of competition of chain-extension, the linear polymers are prepared simul-taneously, and are separated through post-processing. Due to the difficulties of preparing cyclicpolymer, the few samples and the small quantity of type , the theories and properties of the cyclicpolymer are limited.Therefore, that prepares cyclic polymers by the new methods is a veryurgent and challenging research topic with theoretical and practical significance.In this paper, the cyclic o-xylenyl-ethylenebis(dithiocarbamate)(XEBDC) and the cyclictrithiocarbonate o-xylenyl-1,3-dithiolane-2-thione(XDTT) were synthesized by two-phasereaction. and silicagel column chromatography was used to purify the rough product. Thestructures of the new compounds have been proved by FTIR spectra, 1HNMRspectra and meltingpoint measurements.UV Photopolymerizations of styrene and methyl(methacrylate) were carried out to synthesizecyclic polymers by chain extension in the presence of XDTT and XEBDC at -30℃. The cyclicpolymers were characterized byFT-IR,1HNMR,GPC and so on. The dependence of monomerconversion and polymerization time was also dicussed as well as the dependence of Mn,GPC andmonomer conversion. at -30℃,either using XDTT or XEBDC as photo-initiator, the conversionof monomer increased with the advance of time. The PDI of cyclic polystyrene synthesized usingXDTT is about 1.2 but the counterpart using XEBDC is 1.4. However,the molecular weight ofPMMA is higher than PS and the PDI is wider than the latter, propably due to the lowerconcentration of initiator.