Polylactic acid microsphere, polylactic-co-glycolic acid microsphere and method of preparing the same

A method of preparing high molecular polymer microspheres, comprising:

• providing a first solution, wherein the first solution comprises a high molecular polymer and an organic solvent, wherein the organic solvent comprises dichloromethane, chloroform, ethyl acetate or a combination thereof, wherein a weight volume concentration of the high molecular polymer in the first solution is from 2.5% to 20% based on 100% by weight volume concentration of the first solution;
• providing a second solution, wherein the second solution comprises polyvinyl alcohol, sodium carboxymethyl cellulose and an aqueous solution, wherein a weight volume concentration of polyvinyl alcohol in the second solution is from 0.5% to 2%, and a weight volume concentration of sodium carboxymethyl cellulose in the second solution is from 0.1% to 2% based on 100% by weight volume concentration of the second solution;
• adding the first solution to the second solution, and at the same time, agitating the second solution until the high molecular polymer is solidified to form a plurality of high molecular polymer microspheres, wherein a volume ratio of the second solution to the first solution is from 5:1 to 100:1, and the first solution is added to the second solution at a speed of from 5% to 35% of the first solution per minute based on 100% by volume of the first solution;
• and
• collecting the plurality of high molecular polymer microspheres.