Synthesis and characterization of poly(aspartic acid) end its derivatives as biodegradable materials

Three types of modified poly(aspartic acid)s, such as poly(aspartic acid-co-aminocarboxylic acid) (4), alkylamine modified poly(aspartic acid) (5) and crosslinked poly(aspartic acid) (6), were synthesized and calcium-ion chelating ability, hygroscopicity and water absorption were evaluated. The calcium-ion chelating ability of 4 depended on the kind of aminocarboxylic acids and the content of aminocarboxylic acid in the copolymer. The highest value was 3 times higher than that of poly(acrylic acid) with a M-w of 14000. The highly modified PASP, e.g., 50 mol% lauryl amine modified poly(aspartic acid), showed the highest hygrogroscopicity among homopoly(aspartic acid)s and modified poly(aspartic acid)s. The maximum swelling of poly(aspartic acid) hydrogel prepared by the gamma-irradiation of homopoly(as-partic acid) was 3400 g-deionized water/g-dry hydrogel.