Synthesis And Characterization Of A Novel Biomedical Material Polylactic Acid Modified With Itaconic Anhydride

Polylactid acid is considered as a goodwell biocompatible biomaterials. It is becoming a hot and focal point in national and abroad because of its biocompatibility and biosafety. However, it has poor of hydrophilicity and is short of available reactive functional groups to limit it in the field of biomedical. In order to overcome these flaws, a new PLA-bassed material PITLA, which had high hydrophilicity and abundance available reactive functional groups, was prepared from D, L-lactide, methacrylic anhydride and itaconic anhydride. The structures of the synthesized polymers were characterized by nuclear magnetic resonance spectrometer and fourier transform infrared spectrometer. The physical properties were characterized by the means of differential scanning calorimeter, multi-angle laser light scattering and some classical chemical analysis. Futhermore, in order to improve the property of PITLA, we explored the synthesis of DPITLA. The main works and conclusions were as follows:1. Using Sn(Oct)₂ as initiator, PDLLA was prepared of D, L-lactide by melt ring-opening polymerization. The molecular weight of it was about 5,000 by adjusting the amount of reaction initiator Sn(Oct)₂. Then, PDLLA-MAH was synthesized by PDLLA and methacrylic anhydride, and the structures and properties were characterized.①FTIR and 1^HNMR results showed that PDLLA-MAH which the end groups was double bonds was successfully synthesized by reacting of PDLLA and methacrylic anhydride.②The best reactive condition of making PDLLA-MAH were: the reactive temperature and time were 50℃and 1 h respectively, the ratio of PDLLA and methacrylic anhydride was 1:1.5. Moreover, the reacting system carries on under the nitrogen condition.2. PITLA was polymerizade of PDLLA-MAH and itaconic anhydride in toluene dried, initiated by the BPO. An orthogonal test was designed to study the reactive condition. The structures and properties were characterized.①FTIR and 1^HNMR results showed that PITLA was successfully synthesized by free radical polymerization.②The content of the anhydride groups in the PITLA was determined by a modified rhodamine–carboxyl interaction method and the molecular weight were determined on a GPC-MALLS. The result showed that the content of ITA in PITLA was increased but the molecular weight was decreased with the increase of the feed ratio of ITA.③Using the molecular weight of PITLA for the main evaluating indicator, and considerating the content of ITA, the best reactive condition were: the feed ratio of ITA was 10 wt%, the amount of BPO was 5 wt%, and the reaction was heated at 80℃under nitrogen and stirring for 8 h. Then the molecular weight was 4.783×104 and the content of ITA was 5.99%.④Thermodynamic properties of PITLA determined by DSC, and the result showed that glass transition temperature and decomposition temperature of PITLA were higher than PDLLA, and an obvious melting peak appeared in 144.4℃. 3. The static water contact angle and water absorption ratio of PITLA were mainly investigated, which regarded as the evaluating indicators of surface wetability. And in vitro real-time degeneration experiment used for appraising the degeneration performance.①When the content of ITA in PITLA increased, the hydrophilicity of the material was increasing. Considerating the hydrophilicity and molecular weight, we choose the amount of ITA to be 10%.②The degradation rate of PITLA was faster than PDLLA, and the degradation rate reached to its maximum in the fifth to ninth week, leading by two weeks compared to PDLLA.4. DPITLA was prepared from PITLA and hexamethylene diamine in order to overcome the acidity of the degradation product of PITLA. FTIR, 1^HNMR showed that DPITLA was prepared successfully. The HMD content in DPITLA was determined by ninhydrin-amino interaction method and the result conformed to the theoretical values. When the ITA content in PITLA were 4.59% and 5.99%, the HMD content in DPITLA were 4.23% and 5.79% respectively.