Biodegradable surfactant, preparation method and use thereof

1. A block copolymer having a methoxypoly(ethylene glycol) block component and a poly(lactide) block component, being capped with an amino acid group and being represented by formula (I) below:

wherein R represents an acyl amine group, and the formula (II) below:

wherein R 1 is PhCH 2 , or (CH 2 ) 3 NHC(NH)NH 2 and a is an integer of 20-200, and b is an integer of 5-50; the average molecular weight of the block copolymer ranging from 2000-20000; the average molecular weight a methoxypoly(ethylene glycol) block component ranging from 1000-5000; and the average molecular weight a poly(lactide) block component ranging from 1000-10000, wherein when methoxypoly(ethylene glycol) block component and a poly(lactide) block component in a concentration of 10-1000 μg/mL, the cell viability is detected by MTT method is greater than 95%.

2. The method of preparing a block copolymer as claimed in claim 1 , wherein

R represents an acyl amine group, and the formula (II) below:

wherein R 1 is PhCH 2 , or (CH 2 ) 3 NHC(NH)NH 2 and a is an integer of 20-200, and b is an integer of 5-50; the average molecular weight of the block copolymer ranging from 2000-20000; the average molecular weight a methoxypoly(ethylene glycol) block component ranging from 1000-5000; and the average molecular weight a poly(lactide) block component ranging from 1000-10000; and the method comprises the steps of:

dissolving a methoxypoly(ethylene glycol)-poly(lactide) block copolymer and an amino acid in distilled water to form a working solution;

adding a condensing agent into the working solution for reaction at room temperature for 4 to 48 hours to obtain a product solution;

filtering the product solution to obtain a filtrate;

extracting the filtrate by using a polar organic solvent and precipitating the filtrate by a non-polar organic solvent to obtain a precipitation; and

drying the precipitation to obtain the final product;

wherein the molar ratio of the methoxypoly(ethylene glycol)-poly(lactide) block copolymer: amino acid: condensing agent ranges from 1:1-10:0.1-10, wherein when methoxypoly(ethylene glycol) block component and a poly(lactide) block component in a concentration of 10-1000 μg/mL, the cell viability is detected by MTT method is greater than 95%.

3. The method as claimed in claim 2 , wherein the block copolymer is prepared by the steps of:

adding methoxypoly(ethylene glycol) and D,L-Lactide together into a dry flask, wherein the weight ratio of methoxypoly(ethylene glycol) to D,L-Lactide is 1:1;

adding 0.1 g/mL of a stannous octoate dissolved in dichloromethane into the flask, wherein the weight of the stannous octoate dissolved in dichloromethane is 1/2000-1/500 to the weight of either methoxypoly(ethylene glycol) or D,L-Lactide to form a reaction mixture;

heating the reaction mixture to 80-100° C. to dissolve the methoxypoly(ethylene glycol);

stirring and vacuuming the reaction mixture for at least an hour, during which the atmosphere is replaced with nitrogen alternatively for 3 times;

sealing the flask in vacuum to perform a polymerization reaction at 130-150° C. in oil bath for 3.5-24 hours;

cooling the mixture and breaking the sealed flask to obtain a solid;

dissolving the solid with dichloromethane to form a crude solution, precipitating the crude solution with diethyl ether and filtering to obtain a precipitate; and

drying the precipitate to obtain the desired block copolymer.

4. The method as claimed in claim 2 , wherein the molar ratio of the methoxypoly(ethylene glycol)-poly(lactide) block copolymer:amino acid: condensing agent ranges from 1:3:1.

5. The method as claimed in claim 2 , wherein the polar organic solvent is selected from the group consisting of methanol, chloroform and tetrahydrofuran.

6. The method as claimed in claim 2 , wherein the non-polar organic solvent is selected form the group consisting of petroleum ether and n-hexane.

7. A use of a block copolymer as claimed in claim 1 , for a surfactant.

8. The method as claimed in claim 2 , wherein the condensing agent is 3-(ethyliminomethyleneamino)-N,N-dimethyl-propan-1-amine.