The copolymerization of 1,2-cyclohexene oxide (CHO) with carbon dioxide was performed, using supercritical carbon dioxide (scCO2) as both solvent and reactant, to produce an aliphatic polycarbonate. A CO2-soluble catalyst, tetra(pentafluorophenyl)porphyrin chromium(III) chloride (CrTFPPCl), was synthesized and used to catalyze the polymerization in the presence of 4-(dimethylamino)pyridine (DMAP) as cocatalyst. The best yields for the copolymerization (up to ∼75%) were obtained in the temperature range 95−110 °C over a period of 18 h, with a molar ratio of catalyst to monomer of 2.6 × 10-3. High catalyst efficiencies (3.9 kg of polymer/g of Cr) were observed under these conditions. The copolymers consisted predominantly of carbonate linkages (90−97%), and the chain microstructure was analyzed by 1H NMR and 13C NMR spectroscopy. Gel permeation chromatography revealed number-average molecular weights (M n) of the order of 3500. In contrast to previous studies involving supercritical CO2, narrow polymer molecular weight distributions were observed throughout (M w/M n < 1.4).

A new polymer-supported chromium porphyrin has been prepared and fully characterised; its catalytic activity and recyclability were investigated for the ring-opening copolymerisation of 1,2-cyclohexene oxide (CHO) and carbon dioxide (CO2).

We report the successful controlled polymerization of methyl methacrylate in the presence of the catalytic chain transfer agents 5,10,15,20-tetraphenylporphinatocobalt(II) and 5,10,15,20-tetra(pentafluorophenyl)porphinatocobalt(II) (CoTFPP) in supercritical carbon dioxide (scCO 2 ). Low molecular weight polymers with narrow polydispersities have been prepared both at low and high monomer conversion and the chain transfer constant is found to be 1.3 × 10 3 , which is comparable to the value obtained in traditional solvents.Concern over the emission of volatile organic solvents, typically used in polymer synthesis, has prompted researchers to look for less harmful alternatives. Supercritical carbon dioxide has recently emerged as an environmentally benign, nontoxic, and inexpensive alternative to volatile organic solvents. 1 DeSimone and co-workers have shown that scCO 2 is an ideal medium for both homogeneous and heterogeneous radical polymerizations. 2-7 However, homogeneous polymerization has been limited to those polymers soluble in scCO 2 such as amorphous fluoropolymers and poly(siloxanes). 5,6 As a result, the synthesis of poly(methyl methacrylate) in scCO 2 has been mainly limited to heterogeneous, i.e., dispersion, and precipitation polymerization techniques. 3,7 Enikolopyan et al. first reported that porphinatocobalt(II) complexes behave as chain transfer agents in solution radical polymerization. 8 Since then numerous reports in this area have appeared in the literature. 9-12 It is now widely accepted that the process is catalytic, with transfer constants in the range 10 3 -10 4 having been reported (Scheme 1). 8,9,12 Here we report the successful polymerization of methyl methacrylate in the presence of the transition metal catalysts (1) McHugh, M. A.; Krukonis, V.

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New 1,3-dioxane type ionic liquid crystal materials having a terminal double bond were synthesized. The mesomorphic behaviour of these compounds was measured. The principal features of these compounds are a smectic A phase over a very wide range including room temperature, and a low isotropic to mesophase transition temperature (for example, compound 6-1: Cr-22 SmA 25 I ).