The Structure Regulation And Performance Research Of Porous Organic Silicon Material

With the development of material science, people have paid more and moreattention to the development of porous nanomaterials. Porous material s, a kind ofnanostructured material, have high specific surface area, high porosity, low density,low heat conductivity, etc. Meanwhile, organic silicon porous materials play animportant role in the field of thermal insulation and adsorption. In this dissertation,inorganic oxides were doped into methylsilicone to overcome the friability and lowstrength of methylsilicone porous material.Porous methylsilicone (xerogel) monoliths were prepared by sol-geltechnology with methylsilicone oligomer as precursor and ammonia as catalyst.The effects of the catalyst concentration, gel time and temperature on the structureof porous methylsilicone were studied. The morphology and composition of theporous methylsilicone were characterized by means of SEM, FTIR,29Si-NMR,Nitrogen adsorption–desorption isotherms, and TG analyses. The results showedthat catalyst concentration had effect on the physical property and microstructureof the gels. For the porous methylsilicone prepared at5.0M ammonia, the BETsurface area was409.58m2/g. Methylsilicone porous materials were hydrophobicbecause the nonpolar methyl groups attached to Si–O main chains. When thecalcination temperature was up to300℃, porous methylsilicone monoliths werecrushed. Adsorption performance of the tests showed that adsorption capacity ofporous methylsilicone monolithic materials for organic solvent was commonly3~4times as its own, and for water the adsorption capacity was zero.Three kinds of inorganic oxides: Al2O3, ZrO2, TiO2were used asreinforcement, which were mixed with methylsilicone oligomer solution. Theinfluences of reinforcement’s contents on the structure and composition ofporous materials were studied. The microstructure and properties of thecomposite xerogels were investigated by XRD, TEM, FTIR,29Si-NMR, and TG.The thermal stability was investigated through high-temperature calcination.The results showed that the sample mixed with Al2O3、ZrO2can keep intactmonolithic structure after being calcined at400℃for30min, and the samplemixed with TiO2can resisit500℃for30min. XRD and TEM showed thatas-prepared TiO2was the anatase phase. After being calcined in600℃, TiO2wastransformed into rutile phase. The15wt%TiO2-doped methylsilicone wasdetected with existence of both anatase and rutile phase after being calcined at 1000℃. The results of FTIR and29Si-NMR showed that the T3peaksdisappeared and Q4structure units formed for methylsilicone treated at300℃for30min in air. The15wt%TiO2-doped methylsilicone was mainly composed ofT3and samll amount of Q4structure units after500℃treatment, resulting in thehydrophobic and oil-water separation properties.