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Research on Crosslinked Polyphosphazene Micro- & Nano-Structured Materials

Author: ZhuZuo
Tutor: TangXiaoZhen
School: Shanghai Jiaotong University
Course: Materials Science
Keywords: Micro and Nano Materials Polyphosphazene Nanofibers Film Microspheres Morphology stability Surface hydroxyl Ultrasonic power Composite film Nanotube arrays Preparation Surface Modification Type of solvent PVA The degree of crosslinking The final product Topography Self-assembly Nanocomposite Molecular chains
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 64
Quote: 1
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Abstract


The formation mechanism of the crosslinked phosphazene-containing nanofibers was researched in this thesis. Multi-morphology control between monodisperse mircospheres and uniform nanofibers was successfully achieved by facile approach, adjusting the ratio of solvent composition. We also get the novel functional crosslinked microspheres with active hydroxyl groups via one-step precipitation polymerization by polycondensation. These crosslinked phosphazene-containing nano scale materials were mixed into PVA and a novel controlled drug delivery system was formed.Based on the single factor research on the nanofibers preparation, focused on temperature, power of the ultrasonic bath, concentration of monomer, concentration of triethylamine, the acid-acceptor, and the solvent, we get the initial assumption about the nanofibers formation mechanism. The original particles were formed under special molecule weight and crosslinking degree. Then, these particles were arranged in special direction with the chloride bond. The crystal of TEA/HCl also played an important role in this process. After the structure of nanofibers was formed, they grew up by absorbing the oligmers.Monodisperse cyclotriphosphazene containing microspheres with active hydroxyl groups were prepared via a simple, economic and environmentally friendly route, one-step precipitation polymerization. The resulting polymer particles had spherical shapes and smooth surfaces with narrow particle dispersal. From the FTIR spectra and the result of elemental analysis, it was obvious that the content of the hydroxyl groups on the surface was depended upon the feed ratio. The successful esterification with benzoxy chloride demonstrated the high active of the hydroxyl groups on the microspheres’ surface. This interesting approach might open a novel, simple and economic route to preparing the functional microspheres. We mixed these crosslinked phosphazene-containing nano scale materials into PVA and got a novel controlled drug delivery system. The modified members showed better properties in swelling and mechanics. We also set methylene blue as a sample to test the novel controlled drug delivery system. From the result, we found the novel delivery system could release the methylene blue more stable and slower than original PVA swelling delivery system. The novel system has a very interesting research and application future.

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CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials
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