Patent ID: 6919421

Claim:
A method for preparing a polysuccinimide, which comprises, subjecting aspartic acid to polymerization in a solvent of supercritical fluid to form a polysuccinimide; wherein said supercritical fluid is selected from the group consisting of CO 2 , NH 3 , H 2 O, N 2 O, xenon, krypton, methane, ethane, ethylene, propane, pentane, methanol, ethanol, isopropanol, isobutanol, CClF 3 , CFH 3 , cyclohexanol, CS 2 , and a mixture thereof; and wherein the supercritical fluid is used in conjunction with a cosolvent; and wherein the cosolvent is selected from the group consisting of trans-2-hexenyl acetate, ethyl trans-3-hexenoate, methyl caproate, isobutyl isobutyrate, butyl acetate, butyl methacrylate, hexyl acetate, butyl butyrate, pentyl propionate, methyl ethanoate, ethyl caproate, methyl dodecanoate, 2-ethylbutyl acetate, methyl oleate, dodecyl acetate, methyl tridecanoate, soybean oil methyl esters, hexane, heptane, tetradecane, hexadecane, toluene, 1 -hexadecene, 1-dodecanol, 1 -nonanol and a mixture thereof.