聚乳酸/聚乙二醇共混物的结晶与降解行为

针对聚乳酸（PLLA）亲水性差、降解周期长的问题，利用与亲水性高分子聚乙二醇（PEG）共混的方法对其进行改性。采用转矩流变仪制备了不同组成的PLLA/PEG共混物颗粒，系统研究了PLLA/PEG共混物的结晶和熔融、亲水性和在酸碱介质中的降解行为。结果表明，PEG的加入增强了共混物中PLLA的结晶能力，提高了PLLA在降温过程中的熔融结晶温度。PLLA/PEG共混物在等温结晶中表现出比纯PLLA更快的结晶速度。通过改变PLLA/PEG共混物的组成，可调控材料的表面亲水性和降解速率。随着PEG含量的增多，PLLA/PEG共混物的表面接触角降低。PLLA与PLLA/PEG共混物均可在水溶液中降解，共混物的降解速率高于纯PLLA，随着PEG含量的升高和降解液中酸碱浓度的提高，PLLA/PEG共混物的降解速率加快。

Crystallization and degradation behavior of poly(lactic acid)/poly(ethylene glycol) blends

Aiming at the problem of poor hydrophilicity and long degradation period of polylactic acid (PLLA), it is modified by blending with hydrophilic polymer polyethylene glycol (PEG). A series of PLLA/PEG blends with different blend compositions were prepared by melt blending in torque rheometer. The crystallization and melting behavior, hydrophilicity and degradation properties of PLLA/PEG blends were systematically studied. Results shows that the addition of PEG enhances both the crystallization ability of PLLA and its crystallization temperature during cooling. In isothermal crystallization process, the crystallization rate of PLLA in blends is much faster than that of pure PLLA. Hydrophilicity and degradation rate of the material can be tuned by varying the blend composition. The surface contact angle of PLLA/PEG blends decreases with the increase of PEG content. Both PLLA and PLLA/PEG blends can be degraded in aqueous solution; the degradation ability is significantly improved with PEG presents. The degradation rate of PLLA/PEG blends can be accelerated by increasing of PEG content and increasing of acid or alkali solutions concentration.