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Biodegradable material polylactic acid - polyethylene glycol copolymer Research

Author: LiuJia
Tutor: ZhangPing；ChenTianXiang
School: Guizhou University
Course: Chemical processes
Keywords: biodegradable polymer polylactic acid (PLA) polyglycol (PEG) copolymerization degration property
CLC: R318.08
Type: Master's thesis
Year: 2009
Downloads: 123
Quote: 0
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Abstract


PLA is a typical green polymer since it is produced from renewable resources,starch,and can be degraded to lactic acid and finally to carbon dioxide and water under compost condition after usage.PLA is nontoxic,bioabsorbable and biocompatible.It also has good mechanical properties and can be processed by traditional processing methods.Therefore,it has found wide applications not only in biomedical fields as drug delivery carriers,surgical implants and tissue engineering scaffolds,but also in industrial and agricultural fields as general plastics.Because of its bright prospects,PLA has attracted much attention from both industrial and academic fields.In this paper,we used the direct melt-solid state polycondensation method with D,L-lactic acid so as to reduce the cost of polylactic acid and to expand its application.The influence of catalyst types,catalyst quantity,reaction temperature and time on molecular weight were studied and a well-known SnCl2/TSA catalyst was chosed.Then the best reaction condictions were found, meanwhile the craftwork had been chosed best.The best condition of melt polymerization is as followed:S11Cl2/TSA was chosed as the appropriate catalyst and was 0.5%,165℃,reacting 15h and the pressuere was reduced properly.The molecular weight has been achieved 5.0×104.In order to improve its intrinsic hydrophobicity,PEG chain was introduced into PLA main chain.PLA-PEG copolymers had good intrinsic hydrophobicity and copolymers reaction condictions were found.The relationship between the viscosity-average molecular weight of the copolymers,PEG chain length or the molar ratio of lactide to PEG showed the viscosity-average molecular weight of the resulting copolymers increases with the PEG chain length or molar ratio of lactide to PEG.The right reaction condictions were found by orthogonal optimization.It is as followed:PEG/PLA equal to 9,SnCl2/TSA was 0.5%,160℃,reacting 18h.The collect rate has got 78%and.molecular weight has been achieved 5.2×104.PLA-PEG copolymers were studied on water absotption,the hydrolytic degration property and thermal degration property in the physiological salt water.

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CLC: > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > General issues > Biomaterial
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