| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1988: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1987: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Synthetic carbohydrate polymers were prepared by direct polymerization of diaminodisaccharides, diaminotrehalosw and chitobiose, with difunctional electrophiles, and the derived polymers were evaluated as dialysis membranes. These polymers have both carbohydrate nuits and synthetic building blocks in the main chain and are thus expected to have high potentials as novel macromolecular materials with highly sophisticated functions characteristic of polysaccharides.
6,6'-diamino-6,6'-dideoxytrehalose was synthesized starting from trehalose through a sequence of reactions including selective tosylation, acetylation, azidation, deacetylation, and reduction. Chitobise was prepared by hydrolysis of chitosan with hydrochloric acid followed by erparation by column chromatography. Although the overall yields were not very high in both cases, efficient procedures were established.
The monomers were subjected to polyddition with diisocyanates under controlled conditions to ensure high reaction selectivity giving rise to linear polyureas. They had inherent viscosities of up to 0.56 dl/g and showed high solubility in polar solvents unlike chitin, cellulose and some common polysaccharides. The condensation polymerization of these diaminodisaccharides with dicarboxylic acid chlorides also proceeded smoothly, and the corresponding polyamides were obtained. The polyamides showed much higher solubility and were soluble even in water.
The polyureas from diaminotrehalose and diisocyanates had relatively high viscosities and were thus fabricated into membrances. Permeation rates of urea and sodium chloride through the membranes were measured to elucidate the structure-permeability relationship. As a result, the polyureas were confirmed to have high permeability coefficients which were close to those of cellulose dialysis membranes. The membranes prepared after blending the polyureas with polyacrylonitrile showed improved mechanical strength, but the permeabilities decreased to some extents.
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