Patent ID: 9631044
Date: 2017-04-25
CPC Classifications: C08G,C12N

Claim:
1. A method for preparing a polyurethane, the method comprising: 1) adding 1 part by mole of a diol having a number-average molecular weight of between 500 and 4000 to a reaction vessel, stirring and heating the diol to a temperature of between 100 and 120° C., vacuum dehydrating the diol for between 90 and 240 minutes, and cooling the diol to a temperature of between 50 and 80° C.; adding between 1.58 and 7.10 parts by mole of a diisocyanate to the diol, and pre-polymerizing the diisocyanate and the diol under vacuum at the temperature of between 50 and 80° C. for between 1 and 4 hrs to yield a polyurethane prepolymer; 2) dissolving between 0.5 and 6 parts by mole of lysine in a first solvent to yield a first solution, adding the first solution to the polyurethane prepolymer and stirring for between 10 and 30 min to yield a first reaction mixture; stopping stirring and allowing the first reaction mixture to stand for between 10 and 12 hrs, pouring the first reaction mixture into water, and drying a resulting precipitate at room temperature to yield a polyurethane elastomer containing carboxyl groups; 3) dissolving the polyurethane elastomer containing between 0.5 and 2 parts by mole of the carboxyl groups in a second solvent to yield a second solution; adding dicyclohexylcarbodiimide and N-hydroxysuccinimide which are equimolar and are at least 1.2 times the parts by mole of the carboxyl groups in the polyurethane elastomer, and between 0.5 and 2 parts by mole of an amine-terminated polyethylene glycol in sequence to the second solution, and stirring a resulting mixture for between 20 and 30 hrs at room temperature to yield a reaction solution; and 4) adding 0.1 M hydrochloric acid which is between 1 and 3 wt. % of the second solvent to the reaction solution for reaction for between 3 and 6 hrs; filtering a resulting mixture to remove a precipitate from a first filtrate, and dropping the first filtrate into distilled water under stirring to form a uniformly dispersed colloid; filtering the uniformly dispersed colloid to yield a second filtrate; transferring the second filtrate to a dialysis bag having a molecular weight cutoff of between 8000 and 14000, dialyzing the second filtrate in distilled water, changing the distilled water every 4 to 6 hrs, and taking out the dialysis bag after between 5 and 7 days; vacuum freeze drying a colloid in the dialysis bag to yield a functional polyurethane comprising a side chain of amino-terminated polyethylene glycol; or 1) adding 1 part by mole of a diol having a number-average molecular weight of between 500 and 4000 to a reaction vessel, stirring and heating the diol to a temperature of between 100 and 120° C., vacuum dehydrating the diol for between 90 and 240 minutes, and cooling the diol to the temperature of between 50 and 80° C.; adding between 1.58 and 7.10 parts by mole of a diisocyanate to the diol, and pre-polymerizing the diisocyanate and the diol under vacuum at the temperature of between 50 and 80° C. for between 1 and 4 hrs to yield a polyurethane prepolymer; 2) dissolving between 0.5 and 6 parts by mole of lysine in a first solvent to yield a first solution, adding the first solution to the polyurethane prepolymer and stirring for between 10 and 30 min to yield a first reaction mixture; stopping stirring and allowing the first reaction mixture to stand for between 10 and 12 hrs, pouring the first reaction mixture into water, and drying a resulting precipitate at room temperature to yield a polyurethane elastomer containing carboxyl groups; and 3) dissolving the polyurethane elastomer containing between 1 and 4 parts by mole of the carboxyl groups in a second solvent to yield a second solution, adding between 1 and 4 parts by mole of an epoxy-terminated polyethylene glycol to the second solution to obtain a second reaction mixture, heating the second mixture to the temperature of between 110 and 130° C. under nitrogen protection, stirring for between 20 and 30 hrs; transferring the second reaction mixture to a dialysis bag having a molecular weight cutoff of between 8000 and 14000, dialyzing the second reaction mixture in distilled water, changing the distilled water every 4 to 6 hrs, and taking out the dialysis bag after between 5 and 7 days; vacuum freeze drying a solution in the dialysis bag to yield a functional polyurethane comprising a side chain of epoxy-terminated polyethylene glycol; wherein a dosage of the first solvent satisfies that a solid content of the first reaction mixture is between 26 and 39 wt. %; a dosage of the second solvent satisfies that polyurethane elastomer containing the carboxyl groups is between 2 and 10 wt. % of the second solution; the first solvent is a mixed solvent of water and one selected from the group consisting of tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide, and a dosage of water accounts for between 10 and 30 wt. % of the mixed solvent; the second solvent is selected from N,N-dimethylformamide, N,N-dimethylacetamide, or dimethyl sulfoxide; and the number-average molecular weight of the amine-terminated polyethylene glycol or the epoxy-terminated polyethylene glycol is between 200 and 8000.