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以DMF/二氯甲烷(DCM)或丙酮/DCM为溶剂,通过静电纺丝制备了直径为0.89~1.21μm、孔径大小为61~123 nm的PLLA/CA复合多孔超细纤维.探讨溶剂组成、溶剂比例、聚合物浓度和环境湿度对纤维直径、孔径大小和比表面积的影响.通过SEM观察纤维形貌及其孔径大小,通过N2吸附-脱附曲线计算多孔纤维的比表面积.实验结果表明,相比较丙酮/DCM和DMF/DCM溶剂,以丙酮/DCM为溶剂所制备的纤维孔径小、比表面积大.主要因为丙酮/DCM沸点低,溶剂挥发过程越剧烈,聚合物温度降低越多,热致相分离越剧烈,越有利于形成密集的孔.且混合溶剂中随着DCM比例的增加,纤维上的孔密度和比表面积都增加.聚合物浓度从3%增加到15%,形貌从“多孔颗粒”过度到“珠-串多孔纤维”直到最后生成均匀无珠多孔纤维.纤维上纳米孔的形成主要是由于静电纺丝过程中溶剂的快速挥发引起纤维表面温度急剧降低导致热致相分离而产生多孔结构.且纤维中形成了相互贯穿的三维连通孔.因此可以判断此体系主要是旋节相分离机理进行相分离.
PLLA / CA composite porous ultrafine fibers with diameter of 0.89-1.21μm and pore size of 61-123 nm were prepared by electrospinning with DMF / dichloromethane (DCM) or acetone / DCM as solvent.The effects of solvent composition, Solvent ratio, polymer concentration and environmental humidity on the fiber diameter, pore size and specific surface area.The morphology and pore size of the fiber were observed by SEM and the specific surface area of the porous fiber was calculated by N2 adsorption-desorption curve.The experimental results show that, Compared with acetone / DCM and DMF / DCM solvent, acetone / DCM solvent prepared fiber with small pore size and large specific surface area, mainly due to the low boiling point of acetone / DCM, the more violent the solvent volatilization process, the more the polymer temperature decreased, the more heat The more intense the phase separation, the more conducive to the formation of dense pores. And with the increase of DCM ratio in the mixed solvent, the pore density and specific surface area of the fibers increased. The polymer concentration increased from 3% to 15% “Porous particles ” over to “beads - string porous fiber ” until the final generation of uniform bead-free porous fibers.Nano-pores formed on the fiber is mainly due to the rapid evaporation of the solvent during the electrospinning caused a sharp decrease in fiber surface temperature resulting in The thermally induced phase separation produces a porous structure, and three-dimensional interconnected pores are formed in the fibers, so that the system can mainly determine the phase separation mechanism of spinodal phase separation mechanism.