Anionic polymerization of 1,3-cyclohexadiene to prepare block and graft copolymers of poly(para-phenylene)

Anionic polymerization of 1,3-cyclohexadiene using sec-BuLi as initiator in cyclohexane has been investigated. Both soluble and insoluble fractions were formed. The amounts of insoluble polymers were 10 wt % and 30 wt % at room temperature and at 5°C, respectively. The insoluble PCHD fraction was crystalline as determined by X-ray diffraction and DSC analysis (T_m = 178°C). The microstructures of both fractions were determined by high resolution 1H NMR and quantitative 13C NMR spectroscopy. The amount of 1,4-addition for the insoluble fraction in cyclohexane was ≥98% and the cis planomer content was higher for the polymer prepared in cyclohexane than for those prepared in benzene or in cyclohexane with DABCO.; Hydroxyl-end-capped poly(1,3-cyclohexadiene) has been obtained using different initiator systems to polymerize 1,3-cyclohexadiene followed by termination with ethylene oxide. The highest functionality obtained was 90%. The unfunctionalized PCHDs exhibited much lower number average molecular weights than the calculated molecular weight as expected for the occurrence of chain transfer to monomer which forms dead polymer chains. A mechanistic study of chain transfer using MALDI-TOF MS confirmed that no reinitiation occurs in the absence of additive or in the presence of lithium 2,3-dimethyl-3-pentoxide or TMEDA. In contrast, reinitiation was observed in the presence of DABCO.; A series of poly(1,3-cyclohexadiene)-block-poly(ethylene oxide) (PCHD-PEO) diblock copolymers have been prepared by anionic ring-opening polymerization of ethylene oxide using the anion of ω-hydroxyl-functionalized poly(1,3-cyclohexadiene) as macroinitiator and potassium as counterion. The PCHD-PEO was converted to poly(para-phenylene)-block-poly(ethylene oxide) (PPP-PEO) by aromatization. The products were characterized by 1H NMR, TGA, DSC, and SEC.; A series of poly(1,3-cyclohexadiene)-block-poly(L-lactide) (PCHD-PLLA) have been prepared by ring-opening polymerization (ROP) of L-lactide by coordination-insertion mechanism using ω-hydroxyl-functionalized poly(1,3-cyclohexadiene) as macroinitiator and triethylaluminum as coinitiator. The PCHD-PLLA was converted to poly(para-phenylene)- block-poly(L-lactide) (PPP-PLLA) by aromatization. The products were characterized by 1H NMR, 13C NMR, TGA, DSC, UV-vis and SEC.; Methacrylate-terminated macromonomer of PCHD was prepared by reacting the ω-hydroxyl-functionalized poly(1,3-cyclohexadiene) with methacryloyl chloride. The macromonomer was characterized by 1H NMR, 13C NMR and TLC. The radical copolymerization of the macromonomer with acrylates using AIBN as initiator gave low conversion for both the acrylates and the macromonomer. Anionic copolymerization of macromonomer with methyl methacrylate (MMA) gave complete conversion of MMA and incomplete conversion of the macromonomer. Anionic homopolymerization of macromonomer was not successful. Only a small amount of dimer and trimer were obtained under the standard, low-temperature conditions.