Study On The Synthesis Of Alkoxy Functionalized Silanes And Polysiloxane

With the popularization of 5G communication technology,when we enjoy the convenience of 5G communication technology,some problems which hindered the development of 5G communication technology must be solved.How to improve the heat dissipation efficiency of traditional thermal conductive materials is one of them.During the application of 5G communication technology,high-speed data transmission has increased the power consumption of chip-based electronic components and thus generated more heat.If the heat is not exported in time,it will affect the service life of the chip and the operational stability of the entire equipment.Thus,the thermal conductive material has played a pivotal"role".Thermal Interface Materials(TIM)is one of the common thermal conductive materials,awhich are commonly used in integrated circuit(Integrated Circuits,IC)packaging and electronic heat dissipation fields.There are many types of thermal interface materials,including thermally conductive silicone grease,thermally conductive silicone sheet,thermally conductive phase change material,and thermally conductive double-sided adhesive.Among them,the thermally conductive silicone grease is also called thermally conductive paste and it has good fluidity and can be coated on heating devices by process like dispensing,printing,etc.The thermally conductive silicone grease is especially suitable for thermally conductive composite materials with smaller gaps or zero gaps.Thermally conductive silicone grease is made by mixing thermally conductive fillers and polydimethylsiloxane(PDMS).The key to determine the thermal conductivity of thermally conductive silicone grease is whether PDMS and thermally conductive fillers can form a densely packed state.However,the thermally conductive fillers and PDMS unable to be densely stacked due to the active groups on the surface of the thermally conductive fillers,so the thermally conductive fillers needs to be surface treated to have a good compatibility and dispersed evenly with PDMS.The key work of this thesis is to explore the synthetic method of alkoxy functionalized polysiloxane.The synthesized alkoxy functionalized polysiloxanes could react with the active groups on the surface of the fillers to realize the dense packing of thermally conductive fillers in PDMS.Thus,thermally conductive silicone grease with high thermal conductivity was obtained.This thesis is composed of following four chapters.In chapter 1,the progress of the preparation of alkoxy-functionalized polysiloxanes was briefly reviewed,together with the research progress of monochloro-substituted alkoxysilanes,a kind of important raw materials for the synthesis of alkoxy-functionalized polysiloxanes by known mehods reported in literatures.The research objective of this thesis was further clarified in this section.In chapter 2,a series of?,?-hydroxy-terminated polydimethylsiloxanes with different viscosities and different kinds of alkoxysilanes were used to explore the reaction feasibility between silanols and alkoxy groups under the catalysis of organic amines.The surface gel experiments of the obtained alkoxy functionalized polysiloxanes catalyzed by titanate and the ~1H NMR of the alkoxy functionalized polysiloxanes were used to test the modification results of the alkoxy functionalized polysiloxanes.In chapter 3,the feasibility of synthesizing monochloro-substituted alkoxysilanes by acylation and chlorination methods were explored respectively.Tetramethoxysilane,vinyltrimethoxysilane,and tetraethoxysilane were used as raw materials in acylation method and reacted with each kind of acylation reagent.The monochloro-substituted alkoxysilanes were generated in accompany with the corresponding ester compounds through the substitution reaction conducted between alkoxy group and the chlorine atom contained in acylation reagent.The influence of temperature,kinds of catalysts and acylating reagents on the yield of monochloro-substituted alkoxysilanes were investigated in detail.Besides acylation method,the chlorination method,in which a condensation reaction conducted between Si-H bond in triethoxysilane and N-H bonds in trichloroisocyanuric acid(TCCA),was also used to produce monochloro-substituted alkoxysilanes.The effects of temperature,kinds and dosages of catalysts,and dosage of dichloromethane on the selectivity of the obtained monochloro-substituted alkoxysilanes were investigated in detail.In chapter 4,single trimethoxysiloxy-terminated polydimethylsiloxane fluid was prepared by AROP(anionic ring-opening polymerization)method with hexamethylcyclotrisiloxane(D3),a kind of cyclosiloxane with high ring tension,as the monomer,n-butyl lithium as the initiator and trimethoxychlorosilane purified by distillation method as the end-capping agent.The molecular structure of the obtained polymer was characterized by ~1H NMR,and the feasibility of preparing single trimethoxysiloxy-terminated polydimethylsiloxane fluid by AROP technology was verified.