Preparation And Characterization Of Heat-resistant Silicone Oil Containing Phenylboronic Acid Or Pyridineboronic Acid

The silicone materialsrequired higher thermal stability for protecting core device,especially in the fields of aviation,aerospace,electronics,electrical,transportation,etc..In this paper,the hydroxy boron-containing silicone oil was synthesized which has excellent thermal stability in air.Related experimental research is as follows:?1?Dimethyldichlorosilane-Phenylboronic acid?PhPBS?was prepared by using dimethyldichlorosilane and phenylboric acid as raw materials and sulfuric acid as a catalyst.The effects of monomer molar ratio,adding time of dimethyldichlorosilane,the reaction temperature and time,and the source of phenylboronic acid on the thermal stability of PhPBS.PhPBS had good thermal stability which was prepared by the molar ratio of dimethyldichlorosilane to phenylboronic acid was 10:1.1 under the reaction temperature of 120? for 2 h.The temperature of the mass loss 5%?T₅?of PhPBS was451.2? and 366.1? in N₂ and air atmosphere,respectively.The structure of PhPBS was confirmed by FT-IR,NMR,and so on.And The thermal degradation activation energy of PhPBS was calculated by FWO method to be 171.27kJ/mol.In order to further improve the thermal stability of PhPBS,the effects of different blocking agents and phenyl content on the thermal stability of PhPBS were studied.The results showed that the thermal stability of the blocking agent to PhPBS was not obvious.And the thermal stability of the modified PhPBS in air atmosphere was improved by increasing the phenyl content,which had the better thermal stability was prepared by when molar ratio of dimethyldichlorosilane to diphenyldichlorosilane was10:1,and the T₅ was 384.5? in air atmosphere.?2?Dimethyldichlorosilane-4-Pyridineboronic acid?PyPBS?was prepared by using dimethyldichlorosilane and 4-pyridineboronic acid as raw materials and sulfuric acid as a catalyst.The effects of monomer molar ratio,adding time of dimethyldichlorosilane,the reaction temperature and time on the thermal stability of PyPBS.PyPBS had the good thermal stability which was prepared by the molar ratio of dimethyldichlorosilane to phenylboronic acid was 15:1.4 under the reaction temperature of 130? for 4 h.The T₅ of PyPBS was 429.1? and 371.1? in N₂ and air atmosphere,respectively.The structure of PyPBS was comfired by FT-IR,NMR and so on.The thermal degradation activation energy of PyPBS was calculated by FWO method to be 256.55 kJ/mol,which was much higher than that of PDMS and PhPBS.In order to further improve the thermal stability of PyPBS,the effects of phenyl content on the thermal stability of PyPBS were investigated.The results showed thatthe thermal stability of the modified PyPBS in air atmosphere was improved by adding diphenyldichlorosilane,which had the best thermal stability was prepared by when molar ratio of dimethyldichlorosilane to diphenyldichlorosilane was 5:1,and the T₅ was 399.5? in air atmosphere.