Preparation of Macroporous Inorganic Funtional Materials Using Polymer Monolithic Template
|Keywords||3D skeletal polymer SiO2 macroporous materials templating method Reaction-induced phase separation Ultrasonic|
Three dimensional monolithic polymer template has been prepared via Bisphenol A epoxy cured with diethylenetriamine in the PEG1000/PEG2000 mixing medium, using template method we have prepared three dimensional SiO2 macroporous materials in large sizes, and high frequent ultrasonic wave was employed to track the curing reaction of epoxy resin in PEG medium,the experimental results and conclusions are summarized as follows:1. On-line tracking of reaction-induced phase separation has been realized for the first time by using high frequent ultrasonic wave, which is based on the Rayleigh scattering of ultrasonic wave on the interface of a multiphasic system. The new technology was employed to track the curing reaction of epoxy resin in PEG medium. The investigation involved the effects of concentration, reaction medium, amount of curing agent and temperature on the reaction-induced phase separation. Based on an intensive analysis of spinodal demixing in this curing system, a physical model has been put forward, in which two processes have been abstracted to describe the reaction-induced phase separation. One is the process of phase separation, and the other is phase isolation. In the related mathematical model the scattering intensity of ultrasonic wave is expressed as a function of the rates of both phase separation and phase isolation, by which the experimental data from ultasonic tracking have been explained reasonably.2. In order to prepare three dimensional skeletal polymer(3D monolithic polymer template) with low cross-linking density and high hydrophilicity Bisphenol A epoxy was cured with diethylenetriamine in the PEG1000/PEG2000 mixing medium. The reaction-induced phase separation of this system was controlled by changing the weight ratio of PEG1000 and PEG2000. The morphology observation of the resulted polymers showed that the connectivity of epoxy phase strongly depended on the content of PEG2000 and was also influenced by the curing temperature. The role of PEG2000 in the reaction system was found to be similar to that of the dispersing agent in dispersion polymerzation. A 3D skeletal polymer with well-controlled macro-through-pores was prepared by using a mixture of PEG1000 and PEG2000 in 8/1 weight ratio. A unique light-filtrating effect was first time found in the prepared 3D skeletal polymer with divinylbenzene filled in the uniform macro-through-pores. The effect most likely resulted from a total reflection mechanism of light in 3D macro-through-pores.3. Three Dimensional SiO2 macroporous materials have been prepared in large sizes via templating method. The 3D skeletal polymer used as a proper template was prepared by curing epoxy resin in polyethylene glycol mediums using diethylenetriamine as a curing agent. The formation of ultrathin silica film was accomplished on the polymer surface through the insitu hydrolysis of infiltrated ethyl silicate by exposing samples in NH3?H2O atmosphere at 40°C for 12 h. The thickness of silica ultrathin film was controlled in a range of 20～80nm by changing the amount of ethyl silicate participated in the hydrolysis. The polymer templates were removed by calcinations of silica/polymer composites at 820°C. The refractive index of ultrathin silica film was measured to be 1.445 by matching the refractive indexes of filled liquids and the fixed solid films to reach a maximum of light transmittance.