Synthesis and click chemistry of a new class of biodegradable polylactide towards tunable thermo-responsive biomaterials.

A new class of clickable and biodegradable polylactide was designed and prepared bulk polymerization of 3,6-dipropargyloxymethyl-1,4-dioxane-2,5-dione () which was synthesized from easily accessible propargyloxylactic acid (). A homopolymer of and random copolymer of with l-lactide were obtained as amorphous materials and exhibit low of 8.5 and 34 °C, respectively, indicating their promising potentials for biomedical applications. The statistical nature of random copolymers was investigated by DSC analysis and C NMR spectroscopy, which implies the random distribution of terminal alkyne groups along the back bone of copolymers. The efficient click post-modification of this new class of polylactide with alkyl and mPEG azides affords novel hydrophilic biomaterials, which exhibit reversible thermo-responsive properties as evidenced by their tunable LCST ranging from 22 to 69 °C depending on the balance of the incorporated hydrophilic/hydrophobic side chains. These results indicate the generality of this new class of clickable polylactide in preparing novel smart biomaterials in a simple and efficient manner click chemistry.