Study on the synthesis of poly-aspartic acid

Using maleic as raw material,poly-aspartic acid was synthesized by three steps.The optimum conditions of synthesis of poly-aspartic acid were as follows:molar ratio of maleic to urea 1/0.95,reaction temperature 95.0 ℃,reaction time 3.75 h,mass ratio of maleic ammonium to phosphoric acid 1/0.55,amount of sodium hydroxide 7.5 mL,hydrolysis temperature 45 ℃,hydrolysis time 55 min.Under these conditions,the yield of PASP was 83.0%.