K. Tharanikkarasu

Tetraphenylethane iniferters: Polyurethane‐polystyrene multiblock copolymers through “living” radical polymerization

Toluene diisocyanate-based polyurethane iniferters containing tetraphenyl-ethane groups in between polyurethane blocks were prepared by the reaction of isocyanate-terminated prepolymers and 1,1,2,2-tetraphenyl-1,2-ethanediol. When these iniferters were decomposed in the presence of styrene, polyurethane-polystyrene multiblock copolymers were obtained through a “living” radical mechanism. The effect of changing polyol on the Tg, thermal stability, and molecular weight of polyurethane iniferters as well as block copolymers was studied. The molecular weight of the block copolymers increased with increasing both polymerization time and conversion.

Tetraphenylethane iniferters. II. Toluene diisocyanate‐based polyurethane iniferter for “living” radical polymerization of acrylonitrile

A novel polyurethane iniferter, synthesized from equal moles of toluene diisocyanate and 1,1,2,2-tetraphenyl-1,2-ethanediol, was used to polymerize acrylonitrile to assess whether it proceeded via a “living” radical polymerization mechanism. From the kinetic results, the rate of polymerization could be expressed as Rpα[BPT]0.96[AN]1.64. The increase of number-average molecular weight with increase of both conversion and polymerization time, the bimodal molecular weight distribution in gel permeation chromatography and the increase of molecular weight in the post-polymerization of polyacrylonitrile confirm that the present tetraphenylethane-based polyurethane iniferter follows a “living” radical polymerization mechanism.

Tetraphenylethane iniferters—9. Diphenylmethane diisocyanate-based polyurethane-polystyrene block copolymers through “living” radical mechanism

Abstract 4,4′-Diphenylmethane diisocyanate-based polyurethane iniferters containing tetraphenylethane groups inbetween polyurethane blocks have been prepared by reacting isocyanate terminated prepolymers and 1,1,2,2-tetraphenyl-1,2-ethanediol. Polymerization of styrene using these iniferters yielded polyurethane-polystyrene block copolymers through a “living” radical mechanism. The effect of changing polyol on Ts, thermal stability and molecular weight of polyurethane iniferters as well as block copolymers have been studied. The molecular weight of the block copolymers increased with increasing both polymerization time and conversion thereby proving “living” radical mechanism.

A novel polyurethane macroinitiator for free radical polymerization

Abstract Polyurethane macroinitiator (PUMI) has been prepared from toluene diisocyanate and benzopinacol and successfully used to polymerize acrylonitrile (AN). The effects of PUMI and AN concentrations and polymerization time on the yield, number average molecular weight and intrinsic viscosity of the resulting Polyacrylonitrile have been studied.

Synthesis and characterization of polyurethane–polyvinylbenzyl chloride multiblock copolymers and their cationomers using a polyurethane macroiniferter

Polyurethane iniferter prepared from isocyanate end capped prepolymer and 1,1,2,2-tetraphenyl-1,2-ethanediol, has been used to polymerize vinylbenzyl chloride to obtain polyurethane-polyvinylbenzyl chloride multiblock copolymers. Formation of the block copolymers proceeds with increase in both molecular weight and conversion with increasing polymerization time showing that the polymerization proceeds via a “living” radical mechanism. The block copolymers so obtained were converted into their cationomers by the treatment of triethylamine. The block copolymers and their cationomers have been characterized by FTIR, FTNMR, TGA, and DSC studies. The effect of thermal energy on the molecular weight of the macroiniferter in the absence of monomer has been studied in order to understand the mechanism of formation of the block copolymers.

Tetraphenylethane Iniferters. 3. “Living” Radical Polymerization of Methyl Methacrylate Using Toluene-Diisocyanate-Based Polyurethane Iniferter

Abstract Polyurethane iniferter, synthesized from toluene diisocyanate and 1,1,2,2-tetraphenyl-1,2-ethanediol, was used to polymerize methyl methacrylate. The rate equation and overall activation energy have been determined from the kinetic results. The number-average molecular weight of the polymethyl methacrylate increased while increasing both conversion and polymerization time. Bimodal molecular weight distribution was observed in gel permeation chromatography. Molecular weight build up occurs when the postpolymerization of polymethyl methacrylate was carried out. It is hence inferred that polyurethane iniferter acts as a thermal iniferter and follows “living” radical polymerization. Polymethyl methacrylate prepared with the polyurethane iniferter initiates the polymerization of styrene to yield polymethyl methacrylate-polystyrene block copolymers by a subsequent supply of thermal energy.

Polyurethane-polymethacrylic acid multi-block copolymers and their anionomers through “living” radical mechanism

SummaryPolyurethane-polymethacrylic acid multi-block copolymers were synthesized from tetraphenylethane based polyurethane iniferter. Number of polymethacrylic acid blocks and molecular weight of block copolymers increased with increasing polymerization time which proves that the formation of block copolymers is through a “living” radical mechanism. The multi-block copolymers obtained were converted into their sodium anionomers. The multi-block copolymers and their anionomers have been characterized by FTIR, FTNMR and DSC analysis.

Novel Polyurethane Multiblock Copolymers and Their Zwitterionomers Using a Polyurethane Macroiniferter

Abstract Polyurethane-poly(4-vinylpyridine) multiblock copolymers have been prepared by the decomposition of a tetraphenylethane-based polyurethane macroiniferter in the presence of 4-vinylpyridine. The increase in the molecular weight and conversion with an increase in polymerization time proves the “living” radical mechanism. The polyurethane-poly(4-vinylpyridine) multiblock copolymers so obtained were converted into their zwitterionomers by treating with γ-propane sultone. Both block copolymers and their zwitterionomers have been characterized using spectral and thermal techniques.

Tetraphenylethane iniferters—8. Diphenylmethane diisocyanate-based polyurethane iniferter for “living” radical polymerization of methyl methacrylate

Abstract A novel polyurethane iniferter, synthesized from equal moles of 4,4′-diphenylmethane diisocyanate and 1,1,2,2-tetraphenyl-1,2-ethanediol was used to polymerize methyl methacrylate. The rate equation and overall activation energy have been determined using kinetic results. As the polymerization time and conversion increased, molecular weight of the polymethyl methacrylate also increased. Postpolymerization of polymethyl methacrylate in the presence of methyl methacrylate and styrene yields high molecular weight polymethyl methacrylate homopolymers and polymethyl methacrylate-polystyrene block copolymers respectively. Hence, the present polyurethane iniferter acts as a thermal iniferter and follows “living” radical polymerization.

Effect of ionic concentration and counterion on properties of poly(vinyloxyacetic acid)

Poly(vinyloxyacetic acid) and its metal salts show polyelectrolyte behaviour in water. The order of counterion binding to this polymer is K+ > Na+ > Li+ > Ca2+. The glass transition temperature (Tg) of poly(vinyloxyacetic acid) with low ionic content and that of its metal salts are the same as that of poly(vinyl alcohol) whereas poly(vinyloxyacetic acid) with high ionic content shows an increased Tg.