| Due to the unique properties,nanofibers have been applied in many fields,such as biological engineering,electronic engineering,safety engineering and so on.Currently,the main methods of producing nanofibers are composite fiber spinning,phase separation,template synthesis,electrospinning and so on.But electrospinning has an upper hand based on the non-complexity of the production technique,its capacity to produce filament nanofiber and compatibility of mixing different chemical combinations.Therefore,electrospinning is the most popular method of producing nanofibers nowadays.Traditional electrospinning always produces distinct two-dimensional fiber mats with lay by lay structure with a small distance between fibers,thereby limiting the application of these fiber structures in other fields.For instance,when the fiber mat was used for culturing cells,the cells grow mainly on the surface because the diameter of fiber is relatively small(10?),this hinders the penetration of cells deep into the mat,as a result it is difficult to fully express the required features.Thus,researchers focus on creating new ways to produce 3D scaffolds with large pore sizes and high specific pore volume.These new techniques of producing 3D scaffolds include lay by lay,liquid-assisted collection,3D model collection and 3D reconstruction.But,in all of them,the major universal disadvantage is smaller gaps between fibers.In addition,there is lack of clarity when discussing mechanism involved and the regularity stacking behavior of 3D scaffolds when the electrospinning parameters have been changed.Some researcher added a larger quantity of surfactant into electrospinning solution to improve its conductivity,so that the surface specific resistance of fibers will be reduced,when the fiber touch to the grounded collector.Immediately,the charge will be transferred to the collector,and the opposite charge will be transferred to the fiber because of static induction.As a result,the3D scaffolds produced have high specific pore volume due to static repulsion.This research is based on modern and innovation techniques to prepare electrospun 3D scaffolds.Firstly,replacing the surfactant with nano-silver particles to improve the conductivity of electrospinning solution,reduce the volume resistance of fibers,so that the speed and degree of charge transfer will be increased leading to stronger repulsion effect.Secondly,its focused on systematic detailing the effects of electrospinning 3D scaffolds as the electrospinning parameters change in order to uncover the regularity of 3D scaffolds stacking behavior.The COMSOL software was used to simulate the electric field of electrospinning environment to analysis the force imposed on fibers.The main results are as follows:(1)3D scaffolds with high specific pore volume were produced when nano-silver particles was added to the electrospinning solution because it increases the repulsion force and at the same time reduce the volume resistance of fibers.(2)The addition of nano-silver particles into electrospinning solution will facilitate the formation of many branch-like fibers during the electrospinning process.Furthermore,when the fibers touch to grounded collector,the branch-like fibers will easily tangle together to become a mass of entangled fibers,so the 3D scaffolds formed have larger pore.(3)By only changing the electrospinning voltage,the diameter of fibers will decrease when the voltage increases,and the pore size of 3D scaffolds will also decrease.Moreover,the 3D scaffolds will change from belt-like stack to cloud-like stack when the voltage increases.(4)When only the electrospinning speed is increased,the 3D scaffolds'pore size will change from small to a bigger size and then transform back to a small size again,but the diameter of fibers will increase gradually.(5)In this study,super high specific pore volume 3D scaffolds were produced with an approximate weight of 2017 cm~3/g. |
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