Browsing by Author "Sun, Xiaoyu"

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    Concurrent and Sequential Surface Modification of Electrospun Polymer Micro/Nano-Fibers
    (2009-04-23) Sun, Xiaoyu; Orlin D. Velev, Committee Member; Tushar K. Ghosh, Committee Member; Saad A. Khan, Committee Member; Richard J. Spontak, Committee Chair
    Surface modification of nano-fibers with bioactive functional groups has become an arresting research area in recent decades, which provides possibility for the invention of bioactive materials for textiles and biomedical applications e.g. tissue engineering. The major objective of this research is to develop a novel single-step processing route for the production of synthetic fibers possessing specific bioactive surface functionalities at nano/submicron scale. Unlike traditional sequential surface modification of nanofibers, sequence-defined oligo-peptide that carries biofunctionality was synthesized separately before incorporated onto the electrospun fibers as surface functionalities by a single-step spinning process, so as to avoid the effect from chemical synthesis on fiber processing. As one of the most widely-used technologies for the production of polymeric nanofibers, electrospinning was chosen to achieve the single-step surface modification. Conventional homopolymer in conjunction with the biofunctional oligopeptide-incorporated block copolymer were co-electrospun. Nanofibers at submicron scale with surface enrichment of block copolymer were achieved due to phase separation caused by polarizability difference under static electric field. The surface segregation of peptide block was proved by the nitrogen enrichment measured from X-ray Photoelectric Spectroscopy (XPS). The proposed mechanism is discussed based on mainly the model homopolymer system of polyethylene oxide (PEO), and extended to the ternary polymer blends composed of thermoplastic polymethyl methacrylate (PMMA), PEO and block copolymer. The surface modification technique introduced deep insight into the electrospinning process with its effect to the polymer blends microphase separation, and leads to a promising perspective for biomaterial engineers to produce nanofibers with certain surface bio-functional groups.