Synthesis And Microstructure Analysis Of Stereoregular Poly(1,4-cyclohexadiene Carbonate)oligomers

The precise control of polymer microstructure is one of the most important goals in the field of coordination catalysis polymerization.To synthesize the corresponding model oligomers and analyze their ¹³C NMR spectra plays a critical role in qualitative and quantitative analysis of polymer microstructure.Our group have obtained isotactic poly（1,4-cyclohexadiene carbonate）（PCEC）with 99%ee using the chiral dinuclear Co（III）complexes based on biphenol linking bridge.PCEC is a type of polycarbonate that can be further functionalized and modified,but its stereochemical microstructure information is still unclear.In this thesis,（R,R）/（S,S）-cyclohex-4-ene-1,2-diols were used as starting materials to synthesize various isotactic and syndiotactic model compounds（oligomers with 2,4,6,8 and12 degree of polymerization）of PCEC,using N,N’-carbonyldiimidazole and triphosgene as carbonylation reagents.By comparing the signals in the ¹³C NMR spectra of various steroregular oligomers,it can be concluded that the signals at 154.04 ppm,73.83 ppm and 29.91ppm are assigned to carbonyl,methine and methylene of isotactic PCEC,respectivey,while the signals at 153.72 ppm,72.97 ppm and 28.98 ppm are attributed to carbonyl,methine and methylene of syndiotactic PCEC,respectively.In addition,the crystallinity of various isotactic and syndiotactic model compounds of PCEC and their stereocomplexes were studied by differential scanning calorimetry（DSC）and wide-angle X-ray diffraction（WAXD）.The results showed that the crystalline properties of various isotactic and syndiotactic model compounds are significantly different from their stereocomplexes.