Study On Synthesis And Properties Of Hydroxy Acid Polyester

Polylactic acid(PLA) is one of the first studied biodegradable polymers, which have certain degradation and biocompatibility, but its fragile and poor thermal stability, this paper consider introducing a long chain monomer in the PLA to improved its flexibility and thermal stability.A series of lactic acid-10-hydroxydecanoic acid copolymers(PLA-co-PHDA) with different compositions were synthesized by melting polycondensation of lactic acid(LA) and 10-hydroxydecanoic acid(HDA). The structure, molecular weight and its distribution of the copolymers were characterized by FTIR, 1H NMR and GPC. The thermal properties of copolymers were measured by DSC and TGA, the results showed that the introduction o f HDA groups made the decrease of melting temperature(Tm) and glass transition temperature(Tg) of the copolymers, thereby easily to be processed, and also the introduction of HDA increased the Td,5% and Td,max of copolymers effectively, improved the thermal stability of copolymers. PLA-co-PHDA showed high ductility by the introduction of HDA, and the breaking elongation increased from 7% to 600%. Moreover, studied the invasive, biocompatibility and degradation properties of copolymers. The results showed that the properties of PLA-co-PHDA could be regulated by the monomer ratio of LA/HDA in some extent.A series of lactic acid-10-hydroxydecanoic acid-3-hydroxybutyric acid copolymers(PLA-PHDA-PHB) with different compositions were synthesized by melting polycondensation of LA, HDA and 3-hydroxybutyric acid(HB). The structure, molecular weight and its distribution of the copolymers were characterized by FTIR, 1H NMR and GPC. The thermal properties of copolymers were measured by DSC and TGA, and the results showed that the introduction of HDA and HB groups made the decrease of Tm and Tg of the terpolymers, thereby easily to be processed, and also the introduction of HDA and HB increased the Td,5% and Td,max of copolymers effectively, improved the thermal stability of copolymers. PLA-PHDA-PHB showed a certain amount of ductility by the introduction of HDA and HB, and the breaking elongation increased significantly by the increment of the HDA and HB composition. In addition, the invasive and degradation properties of copolymers were also studied. The results showed that the properties of PLA-PHDA-PHB could be controlled by regulated the monomer ratio.A series of macromonomers(PHDA-OH) with different compositions were synthesized by melting polycondensation of HDA with 1,4-butanediol(BD), and then by the ring-opening polymerization of lactide synthesis block copolymers PLA-b-PHDA-b-PLA. The structure of macromonomers and block copolymers were characterized by FTIR and 1H NMR. The thermal properties of copolymers were measured by DSC and TGA, the results showed that with the increasement of HDA/BD, the thermal stability of PLA-b-PHDA-b-PLA increased, and the Td,max of the block copolymers were increased from 270 ℃ to 407 ℃. The invasive of PLA-b-PHDA-b-PLA were also studied, with the increase of HDA/BD, the water contact angle increased, and the hydrophobic of PLA-b-PHDA-b-PLA increased. Therefore, the thermal and invasive properties of PLA-b-PHDA-b-PLA could be regulated by the composition, and they mabye applied in packaging materials.