Development of Nano-Sized Supports for Polymerization

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1. Effect of Iron (III) Hydroxide Sol as a Support for Oligomerization of L-Phenylalanine in Aqueous Solution An oligomerization of L-phenylalanine in aqueous solution was studied in the presence of iron (III) hydroxide sols.2. Effect of gold nanoparticles as a support for oligomerization of L-cysteine in aqueous solution: We studied a new system for the oligomerizaion of amino acids using gold nanoparticles as nano-sized supports. In this system, we used L-cysteine, which is water-soluble and would readily bind to the surface of gold nanoparticles via a thiolate linkage. After oligomerizaion, the gold nanoparticles were re-oxidized with iodine and dissolve in water again. The resulting products were simply isolated by filtration since oligomer is not soluble in water by cross-linking via disulfide bond.3. Polycondensation of Activated Valine Esters in the Presence of a Lewis Acid : We have succeeded in a novel polycondensation of activated amino acid esters in the presence of Lewis acids. When the polymerization of p-nitrophenyl L-valinate hydrobromide was carried out in DMF in the presence of yttrium(III) trifluoromethanesulfonate, a polymer, of which the number-average molecular weight was 3000, was obtained. On the contrary, in the absence of the Lewis acid, no polymer was obtained. These results suggest that the polycondensation of the amino acid ester proceeded by the Lewis acid.