Preparation And Characterization Of Ureidosilane

Organosiloxane polymer has excellent properties, such as good resistance to high temperature, hydrophobic, anti-aging, weathering. It can be applied to all aspects of both national defense and daily life, it has become a promising green material, which also meets age demand and gets rapid development. The synthesis methods of organosiloxane polymer can be divided in two ways-polymerization and condensation. One is the direct condensation between the silanes with active groups at both ends, the other is a class of cyclic siloxane ring-opening polymerization. Because of the uncontrollable of direct condensation, ring-opening polymerization has been mainly used in the industry. If the special high temperature silicone polymer is expected to be prepared, such as the introduction of heat-resistant silicone group into the main chain, ring-opening polymerization is unattainable. In this article, the method of condensation between silanediol and ureido silane was used, which could solve the above difficulties well. And the preparation of the ureido silanes, monomers of the condensation, were also further studied.The main work was as follows:1. Bis (N-tetramethylene) aminomethyl vinylsilane was prepared by anionic reaction and aminolysis of chlorosilane. The product was characterized by FTIR and 1H NMR. The results showed the bis (N-tetramethylene) aminomethyl vinylsilane was prepared successfully. In order to determine the optimum conditions, the ratio of the reaction, the reaction solvent, reaction temperature and reaction time were explored. The best reaction conditions were as follows:(1) the raw material methylvinyl-dichlorosilane and pyrrolidine molar ratio was 1:5; (2) heptane was acted as a solvent; (3) The reaction temperature was-10?-20?; (4) the reaction time was 4 hours.2. The bis (N-phenyl-N'-tetramethyleneureido) methylvinylsilane was prepared by the reaction between the prepared bis (N-tetramethylene) amino methyl vinyl silane and phenyl isocyanate under dry oxygen-free and high-purity argon atmosphere conditions. And the effects of reaction time, reaction ratio and reaction temperature on the yield were studied. The optimum reaction conditions were as follows:(1) The reaction temperature was -10?-20? (2) phenyl isocyanate and bis (N-tetramethylene) aminomethyl vinylsilane ratio was 2.5:1; (3) the reaction time was 3 hours.3. Organic aminosilane with different structure was synthesized by the reaction of dichlorosilane with different side groups, pyrrolidine and diethylamine. Subsequently, the prepared organic aminosilane was reacted with phenyl isocyanate to prepare ureido silane with seven kinds of end groups or pendant groups. The products were characterized by FTIR,1H NMR,13C-NMR, MS and DSC.4.Five different organosiloxane polymers were prepared by the condensation between diphenylsilandiol and the prepared three kinds of ureido silane at a low temperature. The products were characterized by FTIR,1H NMR,13C NMR, GPC, the results indicated the polymers were prepared successfully.5.The thermal performance of the prepared organic silicone polymer was studied by TGA. Both the different atmosphere of degradation mechanisms and the effects of initial decomposition temperature, the kind and amount of lateral groups on heat resistance were discussed. The results showed that polymer had high initial decomposition temperature and high char yield under the both nitrogen and air condition. However, the decomposition mechanism under nitrogen was completely different from that under the air. There was only one step of degradation under nitrogen condition while two steps under air condition. And the initial decomposition temperature of the polymer under air condition was inferior to that under nitrogen condition. And under both air conditions, the vinyl substituted polymer had better heat resistance than the dimethyl substituted siloxane polymer, and with the increase vinyl content the heat resistance became better. And the heat resistance performance of the polymer was improved by the introduction of phenyl group.