The Construction Of Centrifugal Spinning Equipment And One-step Preparation Of Multi-scale Porous PCL Micro-nano Fibers

Micro-nano fiber scaffolds are widely used in the field of tissue engineering because their structures are very similar to extracellular matrix.Porous structures can further increase their specific surface area and promote cell adhesion and proliferation.Multi-scale structures make it easier for cells to grow into the scaffold.At present,the porous and multi-scale structures are mainly built on the surface of the fiber through the electrospinning method,but the electrospinning method also has some problems,such as the need for high-voltage static electricity,the requirements on the polarity of the spinning solution,and the low production efficiency.As a new method for preparing micro-nano fibers,the centrifugal spinning method can better avoid these problems,and it has gradually been favored by researchers in recent years.Therefore,this subject developed a centrifugal spinning device that can quickly prepare multi-scale porous micro-nano fibers,and used the degradable polymer PCL as a raw material to preliminary explore its spinning process parameters.At the same time,the effects of three film forming methods(centrifugal spinning,electrospinning and casting)on the structure and properties of PCL film were compared..The main research contents and conclusions of this thesis are as follows:(1)Design and construction of centrifugal spinning device.According to the different functions of each component,it can be divided into speed control module,liquid storage module,spinning module,airflow field module and collection module.Each module is designed and built according to the expected goal.The precise control of spinning speed can be realized by the speed control module.The outlet can be designed as a spinneret slit by the cooperation of the liquid storage module and the spinning module,so as to realize the construction of multi-scale structure of fiber.The construction of porous structure of fiber can be realized by adding the air flow field into the spinning environment.(2)Research on the centrifugal spinning process parameters(spinning solvent ratio,spinning solution concentration,spinning speed,and whether air flow field is added).The morphology and diameter of the spun fibers were characterized by SEM,and the data was processed by Image-J and Origin software.When the spinning solvent ratio is DCM:DMF=1:0,the spun fiber has an obvious porous structure.With the increase of DMF content in the solvent,the average diameter of the fiber will gradually decrease,and the porous structure will gradually transform into shallow folds until it disappears.The concentration of the spinning solution will affect the difficulty of drawing the jet.Within a certain concentration range,the average diameter of the fiber increases with the increase of the concentration.The spinning speed will affect the centrifugal force.In a certain range of spinning speed,the average diameter of fiber decreases with the increase of spinning speed.The addition of air flow field can accelerate the evaporation of spinning solvent,induce the thermal phase separation of jet and form porous structure,while the surface of fiber without air flow field is groove structure.(3)Research on the structure and performance of three PCL membranes(centrifugally spun film,electrospun film,cast film).SEM,AFM and contact angle results show that the centrifugally spun fiber has a clear porous structure,the surface of the electrospun fiber has only shallow folds,and there are a large number of pores ranging from several microns to tens of microns on the surface of the cast film.Compared with the surface roughness of a single fiber,the centrifugally spun fiber is larger than the electrospun fiber,but the overall roughness of the surface of the centrifugally spun fiber film is smaller than that of the electrospun film,so that the contact angle is also smaller than the electrospun film.TGA and DSC results show that the thermal decomposition temperature of the centrifugally spun film is lower than that of the electrospun film and cast film,the PCL crystallinity of the centrifugally spun film is the smallest,and the PCL crystallinity of the cast film is the largest.In summary,the centrifugal spinning device designed and built in this project can successfully prepare PCL fibers with obvious multi-scale and porous structure,which will provide a certain reference for the application of centrifugal spinning technology in tissue engineering.