Polylactic acid synthesis copolymers

Palumbo, F., Pitarresi, G., Mandracchia, D., Tripodo, G., Giammona, G. (2006). New graft copolymers of hyaluronic acid and polylactic acid Synthesis and characterization. Carbohydrate Polymers, 66, 379—385. 

FIGURE 5 Stepwise synthesis of a triblock copolymer (PCL-PLA-PCL) of PCL and polylactic acid using aluminum coordination catalysts to minimize randomization of the block structure by transesterification. (From Ref. 43.)... 

Lactic acid reacts with diacid or diol to form telechelic polylactic acid, then through further a linking reaction it forms high-molecular-weight lactic acid copolymers [33, 44, 45]. Polymerization of a racemic mixture of L- and D-lactides usually leads to the synthesis of poly-DL-lactide (PDLLA)which is amorphous. Use of stereospecific catalysts can result in heterotactic PLA which is found to show crystallinity [46, 47]. The degree of crystallinity and many associated properties are greatly controlled by the ratio of D to l enantiomers in the polymer [48]. 

Details are given of the synthesis of biodegradable graft copolymers based on a backbone of polylactic acid grafted with short blocks of polyacrylamide. Emulsion and solution polymerisations were examined. Molecular structures were determined by proton NMR and FTIR and by DSC. Cytotoxicity tests were conducted to assess their biocompatibility. Preliminary results of their potential in controlled release technologies are reported. 17 refs. 

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