Jobi Kodiyan Varghese

Preparation of flame-retarding poly(propylene carbonate)

A preparative method for a flame-retarding poly(propylene carbonate) (PPC) was demonstrated by employing diphenylphosphinic acid (Ph2P(O)(OH)), phenylphosphonic acid (PhP(O)(OH)2), or phosphoric acid (P(O)(OH)3) as a chain transfer agent in the immortal CO2/propylene oxide copolymerization catalyzed by a highly active catalyst, a cobalt(III) complex of a Salen-type ligand tethered by four quarternary ammonium salts (1). High turnover frequencies of 10 000–20 000 h−1 (700–1300 g-polymer per g-cat·h) were maintained even in the presence of a large amount of the protic chain transfer agent ([–OH]/[1], 1600–200). Directly after the copolymerization using PhP(O)(OH)2 as a chain transfer agent, thermoplastic polyurethane (TPU) was formed by adding a stoichiometric amount of toluene-2,4-diisocynate. The TPU also was not inflammable. Cone calorimeter studies showed that PPC itself and TPU prepared using PPC-diol emitted significantly less smoke while burning than common plastics, such as polystyrene.

Copolymerization and terpolymerization of carbon dioxide/propylene oxide/phthalic anhydride using a (salen)Co(III) complex tethering four quaternary ammonium salts

Summary The (salen)Co(III) complex 1 tethering four quaternary ammonium salts, which is a highly active catalyst in CO2/epoxide copolymerizations, shows high activity for propylene oxide/phthalic anhydride (PO/PA) copolymerizations and PO/CO2/PA terpolymerizations. In the PO/PA copolymerizations, full conversion of PA was achieved within 5 h, and strictly alternating copolymers of poly(1,2-propylene phthalate)s were afforded without any formation of ether linkages. In the PO/CO2/PA terpolymerizations, full conversion of PA was also achieved within 4 h. The resulting polymers were gradient poly(1,2-propylene carbonate-co-phthalate)s because of the drift in the PA concentration during the terpolymerization. Both polymerizations showed immortal polymerization character; therefore, the molecular weights were determined by the activity (g/mol-1) and the number of chain-growing sites per 1 [anions in 1 (5) + water (present as impurity) + ethanol (deliberately fed)], and the molecular weight distributions were narrow (M w/M n, 1.05–1.5). Because of the extremely high activity of 1, high-molecular-weight polymers were generated (M n up to 170,000 and 350,000 for the PO/PA copolymerization and PO/CO2/PA terpolymerization, respectively). The terpolymers bearing a substantial number of PA units (f PA, 0.23) showed a higher glass-transition temperature (48 °C) than the CO2/PO alternating copolymer (40 °C).

Morphology Control of Polymer Particles in Ethylene/Carbon Monoxide Copolymerization†

molecular-weight polymers. Although Shell discontinued research in this area in 2001, Asian industrial development has continued, particularly in areas related to development of fiber applications. The copolymer is insoluble in common organic solvents and precipitates during copolymerization as irregular snow-white particles of low bulk density (ca. 0.10 gmL ) or as a lump, causing problems in the postreaction processes. Some of the polymer sticks to the reactor walls and agitator, creating a problem in large-scale synthesis called “reactor fouling”. Morphology control of particles is a hot issue of particular importance in the polymer industry. In radical polymerizations, the traditional suspension polymerization technique produces well-controlled polymer beads of 0.01–1.0 mm, which are easy to handle. In commercial production of polyethylene and polypropylene using slurry and gas processes, morphology control is achieved by immobilizing the catalyst on a solid support such as MgCl2 or silica. [7] To control the morphology of the polymer particles in the ethylene/CO copolymerization, a strategy is implemented in this work that mimics the traditional suspension polymerization technique: growing polymer particles from catalystcontaining organic droplets dispersed in water or conversely, from catalyst-containing water droplets dispersed in an organic media. Because common catalyst 1[TsO or CF3CO2 ]2 (TsO , p-toluenesulfonate anion; Scheme 1) is insoluble in both non-polar organic solvents and water, the strategy cannot be directly applicable using 1. To endow some hydrophilicity or lipophilicity, the ligand framework of 1 is modified by replacing the methylene unit (-CH2-) with a -(RCH2CH2)MeSiunit, where R is a sugarcontaining alkyl or a long-chain alkyl (Scheme 2). Treatment