Synthesis, Characterization And Application Of Novel Functional Polyorganosilicons

Because of the special molecular structure and the unique style of chemical bond, organosilicon polymers exhibit many special chemical and physical properties which are different from carbon-based polymers, such as low and high temperature stability, low surface energy, chemical stability, oxidation-resistant and low dielectric constant etc. Therefore, organosilicon materials have received great attentions in electronic, energy sources, chemical and national defence Industries. Usually, organosilicon materials present difficulty in curing, and the process of curing must rely on higher temperature. These problems can prohibit the development of traditional organosilicon. In this thesis, based on reviewing the literatures in this field, the strategy to resolve the problems is stipulated as follows: 1) utilizing the suitable catalyst to promote the curing rate and reduce curing temperature, 2) adopting Ultraviolet radiation curing technique instead of thermal curing. Polysiloxanes with different structures were synthesized according to macromolecular designs. Thermal stability of polymers and the behaviour of photocrosslinkable polysiloxanes were considered as the key points for investigation. Besides, utilizing organosilicon materials with low surface energies, a novel self-cleaning and anti-fouling agent was developedOrganosilicon polymers were synthesized through precursor of polydimethylsiloxane carrying silanol end groups, and their molecular structure were characterized by FT-IR, GPC etc. It was found that the organosilicon polymers can be cured fast, and can possesse a good stability at room temperature. Effects of water, and content of catelyzer on the polycondensation reaction were studied, and the catalysis mechanism of dibutyltin dilaurate was also explored. Thermal stability of polymer after curing was measured, and effects of catalyst, the value of R/Si ratio were investigated. "Ozawa" method was used to calculate the thermal degradation activation energy of organosilicon polymer.Used different monomer, three kinds of photocurable polysiloxanes were synthesized via "adjust-polymerization". It was found that curing atmosphere,initiator type, molecular structure, and the content of photocrosslinkable groups have important influences on curing rate and conversion of unsaturated double bonds. For further understanding the thermal property of the polymers synthesized, thermal decomposion mechanism was investigated by TGA.Hyperbranched polyethoxylsiloxanes were synthesized by "Reverse feed sequence polymerization", and were characterized by FT-IR, 1H NMR, 29Si NMR. The result showed that as there were no silanol groups in the polymer, therefore they exhibited excellent storage stability. Because of the low surface energy, low viscosity, high fluidity and reactivity of hyperbranched organosilicon, a novel coating with excellent self-cleaning, anti-fouling properties and good decorative effects was developed. At last, SEM, Contactor angle techniques were employed to investigate the anti-fouling mechanisms.