热致相分离制备聚乳酸纳米纤维支架

本研究以二氧六环/叔丁醇为溶剂体系，采用热致相分离方法制备出具有多级孔径的三维连通的聚乳酸纳米纤维支架. 探讨了陈化、陈化温度、聚合物浓度、二氧六环/叔丁醇 (溶剂/非溶剂)比例对纳米纤维支架的结构和纤维直径大小的影响. 结果表明，陈化对较低聚合物浓度下(≤7%)纳米纤维结构的形成影响明显，而在较高聚合物浓度时(＞10%)，只要控制在一定温度下相分离即可形成纳米纤维结构的支架；较低的陈化温度(≤5℃)有利于纳米纤维状网络结构(直径约20-300nm)的形成，且随着陈化温度的下降，纤维网络结构分布更加均匀；聚乳酸浓度增加, 纤维细化，网络结构分布更均匀，所形成的孔结构也更致密；叔丁醇含量≤12%时，纤维直径变化不大；当叔丁醇含量＞12%时，纤维直径明显增加(约500 nm).

Fabrication of Poly(L-lactic acid)Nanofibrous Scaffolds by Thermally Induced Phase Separation

A series of poly(L-lactic acid)(PLLA) three-dimensional(3D) nanofibrous scaffolds were fabricated by phase separation from a ternary PLLA/dioxane/tert-butanol system. The effects of aging process, aging temperature, polymer concentration, the ratio of dioxane and tert-butanol on the morphology of scaffolds and the diameter of fibers were investigated. The results show that aging process played a crucial role in forming the unique nanofibrous structure in a lower polymer concentration(≤7%). However, the nanofibrous structure was also obtained by control phase separation in a certain extend of temperature in a higher polymer concentration(≥10%). A lower aging temperature(≤5℃) was proved to be helpful for forming nanofibrous scaffold(diameter of fiber:20-300nm), and the nanofibrous network structure was more uniform as the temperature becomes lower. Furthermore, the fibers become thinner and the nanofibrous network becomes more uniform with increasing the polymer concentration, at the same time the pore morphology tends to be denser. The diameter of fibers did not change statistically when the content of tert-butanol is less than 12%, but it changed obviously, even reached up to 500nm when the content of tert-butanol is more than 12%.