Dear Peng Dong,

find attached files 

Dear Raj koti,

Please find the following attachment

PLGA or poly(lactic-co-glycolic acid) is a copolymer which is used in a host of Food and Drug Administration (FDA) approved therapeutic devices, owing to its biodegradability and biocompatibility. PLGA is synthesized by means of ring-opening co-polymerization of two different monomers, the cyclic dimers (1,4-dioxane-2,5-diones) of glycolic acid and lactic acid. Polymers can be synthesized as either random or block copolymers thereby imparting additional polymer properties. Common catalysts used in the preparation of this polymer include tin(II) 2-ethylhexanoate, tin(II) alkoxides, or aluminum isopropoxide. During polymerization, successive monomeric units (of glycolic or lactic acid) are linked together in PLGA byester linkages, thus yielding a linear, aliphatic polyester as a product.[1]

Depending on the ratio of lactide to glycolide used for the polymerization, different forms of PLGA can be obtained: these are usually identified in regard to the molar ratio of the monomers used (e.g. PLGA 75:25 identifies a copolymer whose composition is 75% lactic acid and 25% glycolic acid). The crystallinity of PLGAs will vary from fully amorphous to fully crystalline depending on block structure and molar ratio. PLGAs typically show a glass transition temperature in the range of 40-60 °C. PLGA can be dissolved by a wide range of solvents, depending on composition. Higher lactide polymers can be dissolved using chlorinated solvents whereas higher glycolide materials will require the use of fluorinated solvents such as HFIP.

Dear Rajkoti Katkuri ,

Thank you for your helpful references. Most of the references used commerical available PLGA uncapped with carboxylic groups. But I want to start with D,L-LA and GA to synthesize PLGA.

I used to apply alcohol to synthesize PLGA with hydroxyl terminal groups. So I wanna if I could use hydroxy acid to initiate the polymerization without complex protection and deprotection process. In that way, can I obtain PLGA with COOH group directly?