Tae Seok Kwon

Living Radical Polymerization of Styrene with Diphenyl Diselenide as a Photoiniferter. Synthesis of Polystyrene with Carbon-Carbon Double Bonds at Both Chain Ends

Abstract Photopolymerization of styrene in the presence of diphenyl diselenide proceeded smoothly. The polymer yields and the number average molecular weight (Mn) of the polymers increased with reaction time. Further, a linear relationship was found for a plot of Mn for polystyrene versus polymer yield. These results indicate that this polymerization proceeds through a living radical mechanism. Photopolymerization of styrene with bis(p-tertbutylphenyl) diselenide afforded a telechelic polystyrene with terminal arylseleno groups. The resulting polymer underwent the reductive elimination of terminal seleno groups by the reaction with tri-n-butyltin hydride. Moreover, this telechelic polymer was treated with hydrogen peroxide to afford polystyrene with carbon-carbon double bonds at both chain ends.

RADICAL POLYMERIZATION OF METHYL METHACRYLATE WITH DIPHENYL DISELENIDE UNDER THERMAL OR PHOTOIRRADIATIONAL CONDITIONS

Polymerization of methyl methacrylate (MMA) with diphenyl diselenide (DPDSE) in the presence of AIBN at 60°C was investigated. DPDSE was worked as a chain transfer agent (CTA). The chain transfer constant (Ctr) of DPDSE for MMA was estimated to be 1.43. On the other hand, DPDSE was functioned as a photoiniferter for the photopolymerization of MMA. In a limited range of conversion, both the polymer yield and number average of molecular weight ([Mbar]n) increased with the reaction time, and the [Mbar]n linearly increased with the yield. The terminal structure of poly(MMA) was investigated by the 77Se NMR spectrum based on Methyl α-phenylseleno isobutylate (MSEPI) as model compound of the ω-chain end of poly(MMA). Further, photopolymerization of poly (MMA) containing phenylseleno group at ω-chain end as a polymeric photoiniferter with MMA effectively afforded a poly (MMA) having higher molecular weight.

Synthesis of polystyrenes with arylseleno groups at the terminal bond, by the free radical polymerization of styrene in the presence of diaryl diselenides, and their conversion to end functional polymers

Abstract Free radical polymerization of styrene in the presence of diphenyl diselenide, initiated by 2,2′-azobisisobutyronitrile (AIBN) at 60°C, was investigated. Diphenyl diselenide worked as a chain transfer agent and its chain transfer constant was estimated to be 28.0, which is remarkably larger than that of the sulphur analogue, diphenyl disulphide. Polymerization with bis( p-tert -butylphenyl) diselenide gave a polystyrene containing a 1-cyano-1-methylethyl group at the α -end and an arylseleno group at the ω -end, respectively, and the degree of functionality was nearly 1.0. The arylseleno group at the ω -end was reduced quantitatively by the reaction with tri- n -butyltin hydride. This group was also eliminated by treatment with hydrogen peroxide, to give an end functional polystyrene with a carbon–carbon double bond at the ω -end. Further, this double bond was converted to an epoxy group by the oxidation with m -chloroperbenzoic acid.

Synthesis of star polystyrene by radical polymerization with 1,2,4,5-tetrakis(p-tert-butylphenyl selenomethyl)benzene as a novel photoiniferter

Abstract 1,2,4,5-Tetrakis(p-tert-butylphenylselenomethyl)benzene was synthesized and used as a tetrafunctional photoiniferter for the polymerization of styrene. Both the yield and the number average molecular weight ( M n ) of polymers increased with reaction time and M n linearly increased with yield of polymer. The polymerization of styrene using this novel photoiniferter permitted formation of star-shaped polystyrene containing arylseleno groups at the chain ends, and the average degree of functionality was 3.2. Photopolymerization of styrene with end-functional star polystyrene as polymeric photoiniferter afforded polystyrene having high molecular weight.

Synthesis of Telechelic Polystyrene by Radical Polymerization Using 1,4-Bis(p-tert-Butylphenylseleno-Methyl)benzene as a Photoiniferter

Abstract 1,4-Bis(p-tert-butylphenylselenomethyl) benzene was synthesized, and used as a bifunctional photoiniferter for the polymerization of styrene. Both the polymer yields and the number average of molecular weights (n) of polymers increased with the polymerization. The polymerization of styrene by this iniferter permitted telechelic polystyrene containing arylseleno groups at both chain ends, and the degree of functionality was 1.9. The seleno groups of both chain ends of polystyrene were reduced quantitatively by tri-n-butyltin hydride. These seleno groups in polystyrene were also eliminated by treatment with hydrogen peroxide to give telechelic polystyrene with carbon-carbon double bond at both chain ends. Further, polystyrene with double bonds was converted to telechelic polystyrene carrying terminal functional groups as epoxy, hydroxy, and iodide group, respectively. † Deceased August 5, 1997

SYNTHESIS OF MACROMONOMER USING END FUNCTIONAL POLYSTYRENE PREPARED FROM p-METHOXYBENZYL p-TRIMETHYL-SILYLPHENYL SELENIDE AS A PHOTOINIFERTER

The end functional polystyrene having phenylseleno group at ω-chain end was prepared from radical polymerization of styrene in the presence of p-methoxybenzyl p-trimethylsilylphenyl selenide as a photoiniferter. The phenylseleno group at ω-chain end in polystyrene was eliminated by hydrogen peroxide. The resulting polystyrene was interconverted quantitatively to polystyrene having epoxy end group by the oxidation with m-chloroperbenzoic acid. The macromonomer having a meth-acryloyl end group was synthesized from polystyrene containing epoxy end group with methacrylic acid in xylene at 140°C. Copolymerization of this macromonomer with methyl methacrylate afforded effectively a graft copolymer composed of a poly-(methyl methacrylate) backbone and polystyrene branches.

Synthesis of diblock copolymers by end functional polystyrene containing phenylseleno groups as polymeric photoiniferter

ABSTRACT Block copolymers of styrene and p-substituted styrene were prepared by photopolymerization of p-bromostyrene or p-methylstyrene in the presence of end functional polystyrene (DPDSE-PST) containing phenyl-seleno groups at the α and ω-chain ends as polymeric photoiniferter. To determine the form of resulting block copolymers, the behavior of chain terminals of DPDSE-PST was investigated. The ability of photoinitiate and chain transfer of β-phenylethyl p-tert-butylphenyl selenide as a model compound of α-chain end of DPDSE-PST was much smaller than that of benzyl phenyl selenide as a model compound of ω-chain end of DPDSE-PST. On the other hand, the polymerization of styrene, prepared by 1,4-Bis(p-tert-butylphenyl) diselenide as photoiniferter, with styrene also revealed a form of the resulting block copolymer was an AB block structure.

SYNTHESIS OF ABA TYPE TRIBLOCK COPOLYMERS BY RADICAL POLYMERIZATION WITH 1,4-BIS(p-TERTBUTYLPHENYLSELENOMETHYL) BENZENE AS A PHOTOINIFERTER

1,4-Bis(p-tert-butylphenylselenomethyl)benzene was used as a bifunctional photoiniferter for the polymerization of methyl methacrylate (MMA). Both the polymer yields and the number average of molecular weights ([Mbar]n) of polymers increased with the polymerization time and the [Mbar]n linearly increased with polymer yield. The addition of MMA to the poly(MMA) with irradiation increased the [Mbar]n of the polymer. Photoirradiation of telechelic polystyrene having phenylseleno groups at both ends as polymeric photoiniferter in the presence of MMA or p-chloromethylstyrene afforded effectively corresponding to the ABA type triblock copolymers. On the other hand, photopolymerization of p-methylstyrene with ABA type triblock copolymer of styrene and p-chloromethylstyrene as polymeric photoiniferter afforded to multiblock copolymer of styrene and p-substituted styrenes.

Synthesis and free-radical polymerization of triazinylstyrene derivatives

Abstract Reaction of 2,4-dichloro-6-p-vinylphenyl-1,3,5-triazine with nucleophilic reagents such as diethylamine, ethanol, diethyleneglycol monomethylether, and ethanthiol in the presence of a base in THF gave the corresponding substituted compounds in moderate to high yields. The resulting monomers, which have two functional groups, polymerized readily in the presence of AIBN at 60°C to afford the corresponding homopolymers. The copolymerization parameters of each monomer were calculated from their copolymerization with styrene. Q values of these monomers were larger than that of styrene, indicating participation of the triazine ring to resonance of the monomers. On the other hand, e values of these monomers were approximately zero because of the electron withdrawing character of the triazinyl group.

Preparation of Polymeric Analogs of N,N-Dichloro-p-Toluenesulfonamide and Their Use for Oxidation of Alcohols, Oxidative Lactonization of Diols, and Chlorination of Carbonyl Compounds

Abstract Insoluble polystyrenes containing sulfonamide moiety were prepared by copolymerization of p-styrenesulfonamide and divinylbenzene with AIBN. The polymers were treated with tert-butyl hypochlorite to afford the polystyrenes containing N,N-dichlorosulfonamide moiety. These functional polymers were used for oxidation of alcohols, oxidative lactonization of diols, and α-chlorination of carbonyl compounds. In most cases, the carbonyl compounds, the lactones, and the α-chlorocarbonyl compounds as the corresponding products were obtained in excellent yields. The spent polymer reagents could be separated from the reaction system by simple filtration, and could be fully regenerated without loss of activity.