| Research Abstract |
Water and aqueous solutions seem to have great promise as reaction media in chemical industries, especially in the synthetic polymer industry, from the viewpoints of incombustibility, safety and economy. In fact, the radical reactions such as suspension polymerization and emulsion polymerization of various hydrophobic vinyl monomers and solution polymerization of various hydrophilic monomers with corresponding radical initiators have long been performed using water as a reaction medium. However, the careful removal of water has been required in many cases of organic synthesis and polymer synthesis based on ionic reactions, because most ionic reactions are ordinarily hindered or blocked by the presence of water. On the other hand, we found recently that esterification reaction of poly(methacrylic acid) with benzyl bromide proceeded quantitatively using DBU as a base in water. This meant that aqueous solutions or water can be used as reaction media for ionic reactions, when appropriate r
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eaction conditions including suitable catalyst system can be designed.
This research project investigated the synthesis of polymers by following polycondensation or by polyaddition reactions in aqueous solutions or in plain water under appropriate reaction conditions.
In 1996, the polyaddition of bis(4-mercaptophenyl)sulfide (BMPS) with m-phenylenebis (2-oxazoline) (MPBO) was investigated. The reaction proceeded smoothly in the mixtures of NMP with water to produce the corresponding poly(amide-sulfide). The polycondensation of adipic acid with mxylylene dibromide was also performed using DBU as a base in the mixed solvents of DMSO with water or in plain water. The reaction proceeded even in water to give the corresponding polyesters, although the rate of the reaction decreased gradually with increasing water in the mixture.
In 1997, the heterogeneous oxidation of poly(amide-sulfide), which was prepared by the polyaddition of BMPS with BMPO in plain water, was performed with 1-3 times the amount of hydrogen peroxide in a dispersion of water at 60=, and it was found that poly(amide-sulfone) was prepared by the oxidization of the polymer.
In 1998, polycondensations of bisphenols such as bisphenol-A (BPA), bisphenol-AF (BPAF), and bisphenol-S (BPS) with bis(4-chloro-3-nitrophenyl)sulfone (BCNPS) were examined using various organic or inorganic bases in mixed solvents of DMAc with water or in plain water. The reactions of bisphenols (BPA, BPAF and BPS) with BCPNS proceeded smoothly to give the corresponding polyethers in mixed solvents of DMAc with water at 60= using DBU as a base, although the rate of the reaction decreased gradually as the water in the solvent increased. Poly(sulfone-sulfide) with high molecular weight was also synthesized with good yields by the reaction of BMPS with BCNPS in the same mixed solvents or in plain water using appropriate organic bases such as DBU and tripropylamine. Less
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