The Synthesis And Properties Of Lactic Acid-based Copolyester And Poly(ester-amides)

Lactic acid is a reproducible organic acid and exists in animal and plant. Polylactide (PLA) is biocompatible and biogradable, and its degradation products are a part of nature recycles. It can be expected that the lactic acid-based polymers, i.e. the homopolymer or copolymers prepared from lactic acid, will be biocompatible and biogradable too. In this thesis, a series of lactic acid-based copolyester, linear and cross-linked poly(ester amides) are synthesized. A diol, derived from lactic acid and ethylene glycol, is allowed to react with succinic anhydride (SA) and maleic anhydride (MAH) respectively to prepare diacid oligomer ELSDA and ELMDA. Then, the intermediate ELSDA and ELMDA are used to prepare lactic acid-based copolyester (PELS), linear and cross-linked lactic acid-based poly(ester amides) such as LELSPEA, LELMPEA, CELSPEA and CELMPEA. As the lactate groups are introduced, these polymers are expected to have potential applications in biomedical field and environment benign field. The effect of reaction conditions on the molecular weights and cross-linking degree of polymers is investigated, the structure of polymers is characterized and the relationships between the structure and the properties of the polymers are well examined. The main results of this paper are summarized as follows:1. A series of copolyester PELS (Mw could be 5.4×10~4), linear poly(ester amides) LELSPEA (Mw could be 1.0 × 10~5) and LELMPEA ([ η ]=0.276dL/g), and cross-linked poly(ester amides) CELSPEA and CELMPEA of different cross-linking degree are synthesized. The molecular weights and cross-linking degree of polymers can be controlled by reaction conditions, by which the properties of polymers can be tailored.2. The structure of the polymers is confirmed with FTIR and ~1HNMR. The thermal properties of the polymers are analyzed with DSC and TGA. XRD...