Synthesis, characterization, and epoxidation of an aliphatic polycarbonate from 2,2-(2-pentene-1,5-diyl)trimethylene carbonate ((c)HTC) ring-opening polymerization

2,2-(2-Pentene-1,5-diyl)trimethylene carbonate ((HTC)-H-c) was synthesized from cyclohexene-4,4-dimethanol in high yield (>80%). This new carbonate monomer was successfully ring-open polymerized to form P((HTC)-H-c) in bulk at 90 degrees C using various organometallic catalysts including aluminoxanes (methyl and isobutyl), BunSnCl4-n (n=1, 2, 3), Bu2Sn(OMe)(4-n) (n=2, 3), ZnEt2, and ZnEt2-H2O. Comparison of these systems showed that the Zn- and Al-based catalysts were preferred for the preparation of high molecular weight polymers in yields greater than or equal to 89% and reaction times of less than or equal to 8 h. For the BunSnX4-n catalysts investigated, values of n = 1 when X is Cl and n = 2 when X is OMe resulted in relatively greater polymerization rates and higher polymer molecular weights. The effects of reaction time and monomer/catalyst molar ratio were investigated for the Al and Zn catalysts. An outcome of this study was determining that the ZnEt2-H2O (1/0.5) catalyst for a monomer/catalyst (M/C) molar ratio of 400 and a 2 h reaction time gave a product with M-n = 276 000 in 98% yield. The P((HTC)-H-c) products were characterized by FTIR, H-1-NMR, C-13-NMR, DSC, TGA, and GPC. NMR results showed that (HTC)-H-c decarboxylation did not occur during chain propagation. P((HTC)-H-c) has a moderate glass transition temperature (T-g = 30 degrees C) with high thermal stability. C-13 NMR at 62.5 MHz did not resolve chain diad sequences although the polymers are likely atactic. Epoxidation of P((HTC)-H-c) vinyl side groups was carried out to various extents by using 3-chloroperoxybenzoic acid at room temperature.