Study Of PLLA Nanofibrous Scaffolds Fabricated By Phase Separation

Firstly,based on the thermal induced phase separation method(TIPS),PLLA nanofibrous network scaffolds were fabricated by using 1,4-dioxane/polyethylene glycol(PEG)as the solvent system.The effects of the molecular weight of PEG;aging treatment,aging temperature or gelation temperature and the ratio of solvent/nonsolvent on the morphology of PLLA nanofibrous scaffolds had been investigated.Through SEM images,as the molecular weight of PEG decreased,it was obviously showed the tendency of PLLA scaffolds forming nanofibrous network structure.While PLLA dissolved in solvent with the molecular weight higher than 1500 adding an aging treatment,the polymer could also form the nanofibrous network structure.Besides,the decreasing of aging temperature or gelation temperature would not only lead to the average of fibers’diameter thinner and the length shorter,but the more homogeneous of the nanofibrous structure as well.In addition,when the ratio of solvent/nonsolvent changed,especially the increase of nonsolvent,PLLA scaffolds had changed to a larger pore structure and thinner diameter on account of the nonuniform degree rised.Secondly,similar to the first part,PLLA scaffolds with nanofibrous structure were finally fabricated using the gel extraction phase separation in the solvent system of 1,4-dioxane/polyvinylpyrrolidone(PVP).Although the scaffolds without aging treatment also had certain hole structure,the polymer solution after aging treatment could obtain three-dimensional porous scaffolds with nanofibrous network structure.The change of gelation temperature and aging temperature had a great effect on the forming of nanofibrous structure.While the temperature got to be lower,the more uniform structure with a length shorter and fiber diameter thinner would became gradually and the most evenly when aged at 20 ℃.Besides,increasing the percentage of PVP lead to the bigger hole,and the diameter of nanofiber went up after dropping as the concentration of PLLA increased.Finally,we first compounded some nanoscale hydroxyapatite powders(n-HA)by using the template synthesis.After that,the powder and PLLA were dissolved together in 1,4-dioxane/PEG solvent system to fabricate n-HA/PLLA composite scaffolds with the theory of TIPS.The quantity of n-HA had been investigated which might influenced the morphology of the composite scaffold.Images of SEM showed that,when the content of n-HA was 5%,the morphology of the composite scaffold was the most evenly with nanofibrous structure,and the crystallinity of PLLA also turned to the maximum.The hydrophilicity of the composite scaffolds had a great improvement than PLLA scaffolds as the content of n-HA increased.