The Preparation Of Fluorine-Containing Particles Via Photopolymerization In Supercritical Carbon Dioxide

It has been the potential threat to the ecology environment that large amount of traditional organic solvents are consumed in chemical industry, especially the chlorofluorocarbon solvents used for the synthesis of fluoropolymer, are causing irreversible damage to the atmosphere. Therefore, the mission of seeking for a new type of green solvent seems to be urgent and necessary.Supercritical carbon dioxide is drawing the public attention gradually and is applied to raw material processing and industrial manufacture, by its advantages of mild operate condition, nontoxic, incombustible, inexpensive and easy to get, and the excellent characteristics of low viscosity, high diffusion coefficient and zero surface tension. It is worth mentioning that compared with non-fluoropolymer, fluoropolymer has high dissolvability in supercritical carbon dioxide, which could be the ideal place for the synthesis and processing of fluoropolymer.This research will provide important references for theory and application of the interdisciplinary field in supercritical fluid, fluoropolymer and photopolymerization, the main work and results are as follows:1. Fluorine-containing binary and ternary polyacrylic acrylate (FBPAA and FTPAA) were prepared by two-step way of radical random copolymerization and acylation reaction. A series of oligomers were synthesized with different double bond content, molecular weight and fluorine content by controlling the reactant ratio and the amount of chain transfer agent, and the structure and properties of oligomers were characterized. With the increase of fluorine content, the thermostability of the oligomers was enhanced; with the decrease of molecular weight and fluorine content, the glass transition temperature decreased, and the double bond conversion and reaction rate increased.2. Fluorine-containing oligomers were used as reactant for the preparation of particles via photopolymerization in supercritical carbon dioxide. Single factor experiment method was adopted to investigate the result impacted by the change of each variable. Most of the fluorine-containing particles were uniform spheres, particle size was less than 5?m, and presented bimodal distribution. Well morphology particles were prepared using the formula of 4 wt% TPO,30% double bond content oligomer and DCM as the cosolvent. With the increase of double bond content, cosolvent polarity and oligomer concentration, the phenomena of agglomeration and secondary polymerization became severe. Increasing the reaction temperature, the particle size decreased, and increasing the reaction pressure, the particle size increased.3. The fluorine-containing particles obtained were detected with certain proportion of residual double bond. So particles were dispersed into TPGDA with the mess fraction of 2%, and then the mixture was photopolymerized into resin bars. With the addition of fluorine-containing particles, the crosslink density of the substrate increased, the hydrophobic property was improved, water absorption was reduced, and the thermostability was enhanced.