부산대학교 도서관

Electrospinning has been considered as the one of the most promising approach with which to produce continuous nanofibers on a large scale, and the fiber diameter can be adjusted from nanometers to micrometers. Electrospinning is an efficient and versatile technique to be used for the fabrication of polymer nanofibers. When the diameters of polymer fiber materials are shrunk from micrometers to submicrons or nanometers, several amazing characteristics appear, such as a very large surface area to volume ratio, flexibility in surface functionalities, and superior mechanical performance compared to any other known form of the material. These outstanding properties make the polymer nanofibers optimal candidates for many important applications. 3D printing or additive manufacturing is a process of making three dimensional solid objects from digital files. The creation of a 3D printed object is achieved using additive processes. In an additive process, an object is created by laying down successive layers of material until the entire object is created. Chitosan has many physicochemical and biological properties that make it an attractive material for use in various applications. These properties include biodegradability, lack of toxicity, anti-fungal effects, wound healing acceleration, and immune system stimulation. Chitosan may be used to inhibit fibroplasia in wound healing and promote tissue growth and differentiation in tissue culture. Fibers made of chitin and chitosan are useful as absorbable sutures and wound dressing materials.In this dissertation, multilayer films were fabricated based on chitosan using electrospinning and 3-D printing techniques. The composite multilayer film combines physically distinct components into a single product in order to provide multiple functions, such as a bacterial absorption and adhesion. In this study, three types of multilayer films with different structures were researched. Firstly, a composite multilayer film was prepared by electrospinning. The multilayer film consists of thermoplastic polyurethane (TPU) fiber (outmost layer), poly (acrylic acid-co-acrylamide)/poly (vinyl alcohol) fiber (middle layer) and chitosan/polyethylene oxide (PEO)/mica (innermost layer). This film is helpful in improving flexibility, hydroscopicity, and antibacterial properties. The chitosan/PEO/mica layer is a semi-adherent and non-adherent material that allows moisture to travel through it to the next layer. It also has excellent antibacterial properties. The poly (acrylic acid-co-acrylamide)/poly (vinyl alcohol) layer is a super-absorptive synthetic material that has a high capacity of water-absorption. The outermost layer protects the wound from bacterial invasion and allows air to circulate. Secondly, a multilayer film was prepared using electrospinning and 3-D printing techniques. Thermoplastic polyurethane was used for the frame of the multilayer film. It was created using 3-D printing. The nanofiber membrane was electrospun on the TPU framework. Various shapes of frameworks can be printed by 3-D printers. Thirdly, trans-polyisoprene/(chitosan/polyethylene oxide/mica) core-shell structure nanofibers were fabricated using electrospinning technology. The main advantage of this method is the enhancement of electrospinnability of a relatively less spinnable material with the help of a highly spinnable material that is used either as core or shell. These composite multilayer films possess potential applications in the field of drug delivery, tissue engineering, and wound healing.