ABSTRACT:The phase-transfer polymerization of methyl methacrylate with tetrabutylammonium chloride (TBACl)--Na 2S2 OcCCl4 initiator system was investigated in an aqueousorganic two-phase system. The initial rate of polymerization (Rp) was found to be proportional to the fed quantity of TBACI and square root of the fed quantity of Na2 S2O4 and CCl4 . A cyclic phase-transfer initiation mechanism has been proposed to account for the experimental data.KEY WORDS Phase-Transfer Polymerization / Methyl Methacrylate / Tetrabutylammonium Chloride/ Sodium Dithionite / Carbon Tetrachloride/ Many studies have been made on the phase-transfer-catalyzed reaction because of its preparative usefulness. A wide variety of reactions such as anionic displacement, alkylation, arylation, oxidation, reduction, and hydrolysis could be effectively accelerated by phase transfer catalysts. As for the applications of polymerization reactions, they have been successfully employed in condensation polymerization 1 and anionic polymerization. 2 Recently several authors reported the use of phase transfer catalysts for free-radical polymerizations of hydrophobic vinyl monomers in aqueous-organic two-phase. 3 In most cases, peroxydisulfate was used as a water-soluble initiator with a phase-transfer catalyst such as crown ethers or quaternary ammonium salts. During the course of our investigation on aqueous-organic two-phase polymerization 4 we found that the addition of tetrabutylammonium chloride (TBACl) as a phase-transfer catalyst to Na 2 S 2 0cCC1 4 initiator system induced radical polymerization of methyl methacrylate (MMA) under mild condition. On the basis of kinetic studies an initiation mechanism is suggested for the polymerization of MMA with TBACl-Na2 S20cCC14 in aqueous-organic two-phase system.

ABSTRACT:The photopolymerization of methylmethacrylate (MMA) with methyl viologen (MV 2 +)-Na2 S20 4-CC14 initiator was studied in aqueous-organic two-phase system. The initial rate (Rp) of photopolymerization was proportional to the square root of fed quantity of initiator components, MV2+, Na2 S20 4 , and CC14 , respectively. Rp, however, decreased when MV2+ or CC14 was fed beyond a certain value. RP also gradually decreased in the presence of a large excess of CCl4 . A cyclic phase-transfer initiation system has been proposed for this photopolymerization on the basis of MV+ · cation radical disproportionation.

ABSTRACT:The photopolymerizations of methyl methacrylate (MMA) with N-cetylpyridinium bromide (CPB) and N-cetylpyridinium chloride (CPC) were investigated in aqueous system. With CPB alone, photopolymerization did not proceed, but by the addition of a small quantity of CCI4 , it was significantly accelerated. The rate of the photopolymerization of MMA with CPB in the presence of CCl4 showed a linear relationship with the square root of CPB concentration, but was little affected by the concentration of CCI4 . With CPC MMA also photopolymerized in the presence of CCI4 , and especially at more than a critical micelle concentration (CMC) of CPC, the time-conversion curve showed a characteristic feature of emulsion polymerization, where Rp was proportional to the 0.75 power of the fed quantity of CPC, but almost independent of CCl4 concentration. The above photopolymerizations with CPB and CPC in the presence of CCl4 were, however, remarkably accelerated by the addition of KBr.KEY WORDS Photo-Emulsion Polymerization / Photo-Suspension Polymerization / Methyl Methacrylate / N-Cetylpyridinium Chloride / NCetylpyridinium Bromide / Carbon Tetrachloride /

ABSTRACT:The photopolymerization of methyl methacrylate (MMA) with l-benzyl-1,4-dihydronicotinamide (BNAH) was investigated in the presence of CCl4 . The rate of photopolymerization of MMA with BNAH was remarkably accelerated by the addition of CC14. The fluorescence spectra of BNAH in the presence of various concentrations of CC14 showed that the photoexcited BNAH (BNAH*) was quickly quenched by CCl4 . The spectral change of BNAHCCl4 system during UV-irradiation indicated that the absorption band (Jcm.,, 350 nm) of BNAH disappeared and the pyridinium band appeared at 260 nm. These results suggest that the polymerization is initiated by the following mechanism. Hydrogen transfers from BNAH* to CC14 , and consequently 1-benzylnicotinamide radical (BNA·) and CC13• are generated. The BNA· quickly reacts with CCl 4 to produce 1-benzylnicotinamide chloride (BNA '·c1-) together with CCl3• radical. The produced BNA + Cl -also photodecomposes into BNA· and Cl· radical. The CCl3• and Cl· are able to initiate the polymerization. This photopolymerization could be performed in aqueous-organic two-phase system, and three components BNA + Cl--Na2S2OcCC14 were found to act as a cyclic phase-transfer photoinitiator system. KEY WORDSPhotopolymerization / Methyl Methacrylate / l-Benzyl-1,4-dihydronicotinamide / 1-Benzylnicotinamide Chloride / Carbon Tetrachloride / Sodium Dithionite / Phase Transfer / Photoinitiator / NAD+ and NADH, coenzymes of alcohol dehydrogenase, play an important role in biological redox systems. The details of their reactions in biological redox systems, however, have not been clarified, and several compounds, such as l-benzyl-3-carbamoylpyridinium salt (BNA +) and l-benzyl-1,4-dihydronicotinamide (BNAH), have been used as models of NAD+ and NADH, respectively.The nonenzymatic reactions with these models are known to require a cofactor. For example, the reductions of carbonyl group with NADH models should be accelerated by metal ions, such as Mg2+ and Zn 2 +_i-3 NADH models could also be activated by irradiation with UV light. 4 -6 As far as reported, 7 • 8 a mechanism involving electron-proton-electron-transfer three-step processes may be dominant for nonenzymatic reaction with NADH models.However, the actual features of the reaction with NAD + and NADH are still obscure. In the preceding paper, 9 the authors carried out the photopolymerization of vinyl monomers in order to elucidate whether a radical intermediate was incorporated in the reaction system containing NADH. Methyl methacrylate (MMA) was photopolymerized well with BNAH and the polymerization was found to proceed in radical mechanism and to yield a low molecular weight polymer containing a 275

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