Fabrication And Properties Of Polymer/mesoporous Silica Functional Composites

Polymer-based packing materials have been applied in electronic packing field more and more widely, due to their low density, good electric insulation, excellent dielectric property, low cost and good processible property. The polymer-based packing materials with low dielectric constant and dielectric loss are required in the ultra large-scale integrated circuit chips. Therefore, the exploitation of polymer and polymer-based composities with low dielectric constant is one of the research focuses. At the same times, the polymer-based packing materials with excellent flame retardance are also in need. With regard to the environmental effects and health restrictions, the research on halogen-free and environmentally friendly flame-retardant epoxy resins has great economic and social benefits.This thesis is focused on two parts: one is the study on preparation and properties of epoxy resins/mesoporous silica functional composites; the other is on preparation and properties of PI/mesoporous silica composites with low dielectric constant. The main research contents are as follows:1. A series of well-ordered mesoporous silica materials was synthesized by using the nonionic triblock Copolymers P123, F127 and P104 as templates via the sol-gel prosess. These mesoporous silica materials show well-ordered mesostructures, such as two-dimensional (2D) hexagonal, three dimensional (3D) body-centered cubic, 3D face-centered cubic structure and 3D worm-like mesostrcuctures, and have larger pore diameters (5.4～9.5 nm) and pore volumes. These special mesostructures and large pore volumes indicate the amount of air voids stored in the mesoporous silica materials, which have the potential applications in the fields of low dielectric materials;2. The mesoporous silica materials with the different mesostructures were firstly incorporated into polyimide (PI) and epoxy resins, in order to incorporate the air with dielectric constant of 1 into the resins. The results show that mesoporous materials can remarkably decrease the dielectric constant of the composites. The SBA-16 with pore volume of 0.68 cm~2/g and 3D body-centered cubic mesostructure can more effectively decrease PI than the other mesoporous silica materials. The dielectric constant of the composites decreases from 3.34 to 2.61 and by 21.86%. The dielectric constant of the brominated epoxy resin/SBA-16 composite decreases from 4.09 to 3.90. At the same times, this method combined the low-dielectric constant of mesoporous silica and the excellent properties of PI or epoxy resins, which provides a sample and effective means to prepare the low dielectric constant polymer-based composites;3. The factors, like the mesostructue, morphology and distribution of mesoporous silica materials are firstly investigated how to affect the dielectric constant of the composites. The reasons for the remarkable decrease of the composites are firstly and entirely illuminated through theoretical analyse and calculation via models. The reduction of the dielectric constant is attributed to the incorporation of the air voids (ε= 1) stored within the mesoporous silica materials, the air volume existing in the gaps on the interfaces between the mesoporous silica and the polymer matrix, and the free volume created by introducing large sized domains. At the same times, the morphology and distribution of mesoporous silica materials also affect the dielectric constants by determining the air volume existing in the gaps on the interfaces between the mesoporous silica and the polymer matrix, and the free volume created by introducing large sized domains.4. A phosphorus-containing oligomer, bis(3-hydroxyphenyl) phenyl phosphate (BHPP), was synthesized through the reaction of phenyl dichlorophosphate and 1, 3-dihydroxy-benzene. Consequently, the phosphate-based epoxy resins with a phosphorus content of 1 wt% and 2 wt% were prepared via the reaction of diglycidyl ether of bisphenol-A with BHPP and bisphenol-A. Phenolic melamine, novolak, and dicyanodiamide (DICY) were used as curing agents to prepare the thermoset resins with the control and the phosphate-based epoxy resins. Thermal properties and thermal degradation behavior of these thermoset resins were investigated by using differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). The limited oxygen Index measurement and the UL94 vertical test show that a synergistic effect from the combination of the phosphate-based epoxy resin and DICY curing agent can result in a great improvement of the flame retardance for their thermoset resins. The mesoporous silica can also decrease the dielectric constants of the phosphate-based epoxy resins; however, their effect on the reduction of dielectric constants of the composites is not remarkable due to the big polarity of phosphate group.