热致相分离法制备聚乳酸多孔膜

Porous Poly(L-Lactic Acid) Films Prepared by Thermally Induced Phase Separation

以N,N-二甲基甲酰胺(DMF)为溶剂,采用热致相分离方法制备出不同形貌聚乳酸(PLLA)多孔膜。通过差示扫描量热实验测定了PLLA/DMF溶液的结晶温度及制备的多孔膜的热力学性能;采用扫描电镜和X射线衍射仪表征了PLLA多孔膜的形貌及晶型。结果表明,随着溶液浓度的增大,PLLA结晶温度逐渐升高。低浓度溶液中得到纳米纤维网状PLLA多孔膜,高浓度溶液中制备出微球状PLLA多孔膜;纤维网状和微球状PLLA分别为α’和α晶型,形成机理分别是液-液相分离和成核结晶生长。同时,随着浓度的增大,PLLA熔点(Tm)略有升高。

A series of porous poly(L-lactic acid)(PLLA) films were fabricated from PLLA/DMF solutions by thermally induced phase separation. The crystallization temperatures of PLLA/DMF solutions and thermal properties of porous PLLA films were examined by DSC. The morphology and crystal form of PLLA films were measured by SEM and XRD,respectively. The results show that the crystallization temperature gradually increases with PLLA concentration increasing. The film with nanofibrous network structure is obtained from low concentration solution,while film with porous microspheres is obtained from high concentration solution; the crystal form is α'and α-form,respectively; the formation mechanism for the PLLA nanofibrous network and microspheres is liquid-liquid phase separation,nucleation and crystal growth,respectively. In addition,Tmof PLLA films increases slightly with increase of PLLA concentration.