"active" / Controlled Radical Polymerization Method Ramie Fiber-based Fluorine-containing Composite Materials

Ramie cellulose was produced in China, and then taken to Korea, U.S.A, Japan, and some South America Countries. From the statistics of ramie productivity, China is the biggest product area of ramie cellulose, which takes up about 90% of ramie product all over the world. Ramie cellulose has several excellent properties, such as high tensile strength, coolness, ventilation function, excellent thermal conductivity, moisture absorption and antibacterial function. These properties are very advantageous for the industrial application of ramie cellulose. However, the properties of high degree of orientation and crystallization restrict further utilization and exploitation of the industrial application of ramie cellulose. So, seeking new technique would be important to broaden the application of ramie cellulose, to promote economic development of areas, and to enhance the level of human's living.Supercritical carbon dioxide (scCO2) is a new green solvent, which can substitute regular organic solvent in certain reaction systems and has huge meaning for protecting environment. Reverse addition-fragmentation chain transfer (RAFT), a "living"/controlled radical polymerization method, over traditional polymerization technique, is of promising and particular interest. RAFT technique as a wider range of functional monomers is available under the mild-demanding reaction conditions. Utilizing RAFT technique polymerization synthesized 2,2,2-trifluoroethyl methacrylate (TFEMA) grafting from ramie cellulose in scCO2, which is a new green route to prepare ramie cellulose composite. The ramie cellulose composites were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), size exclusion chromatography (SEC), and contact angle measurements (CA). The contact angle of ramie cellulose composite (24 h) was 149°, which indicated modified ramie cellulose has high hydrophobic property. The homo-polymer (homo-PTFEMA) was prepared in the polymerization, which was also analyzed by size exclusion chromatography (SEC) to estimate the polydispersity indices of grafting chains from the surface of ramie cellulose composite. The results indicated narrow polydispersity with the polydispersity indices (PDI) of 1.28. Thus, this new synthesis route provided a new and environmental friendly approach to prepare the functional composite material for using the abundant ramie cellulose resource.Atom transfer radical polymerization (ATRP), also as a "living"/controlled radical polymerization method, is of new and efficient route for synthesizing polymers with well controlled molecular weight, low polydispersity, and amazing architectures. ATRP technique is a robust and versatile approach to accurately control chain length and polydispersity, which can prepare a great deal of polymer with different function and structure. Utilizing ATRP technique synthesized 2,2,2-trifluoroethyl methacrylate (TFEMA) grafting from ramie cellulose, which is a new route to prepare ramie cellulose composite. The ramie cellulose composites were analyzed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), scanning electron microscopy (SEM), size exclusion chromatography (SEC), and contact angle measurements (CA). The contact angle of ramie cellulose composite (36 h) was 141°, which indicated modified ramie cellulose has high hydrophobic property. PTFEMA was obtained by hydrolyzing the ramie cellulose composite, which was analyzed to estimate the polydispersity indices of grafting chains from the surface of ramie cellulose by SEC. The results indicated narrow polydispersity with the polydispersity indices (PDI) of 1.31. Thus, this synthesis route provided a new approach to prepare the functional composite materials by ATRP technique.This thesis employed RAFT technique to prepare ramie cellulose functional composite in supercritical carbon dioxide, which was a novel and green "living"/controlled radical polymerization method. Moreover, this route provided a new approach to expand the application of supercritical carbon dioxide in polymerization area.