The Preparation Of SiO₂ Aerogel Microspheres And The Suspension Polymerization With Polystyrene

SiO₂ aerogel with mesoporous structure have an excellent insulation performance, but low strength, brittle, high cost restricts its wide application; Use SiO₂ aerogel as matrix, or fillers, or forming an interpenetrating network structure with the organism to strengthening and toughening SiO₂ aerogel have made significant progress. In this paper, composite SiO₂ aerogel with GE Plastics PS to preparation aerogel-SiO₂/PS core-shell materials; EPS foam board with closed pore have excellent insulation properties, high strength, easy processing, is widely used as insulation material under normal and low temperature, therefore, the novel materials will have broad application prospects.Firstly, the preparation of SiO₂ aerogel with controllable morphology and different particle diameters is studied. When using TEOS as precursor, it can’t form the inverse emulsion with the prepared emulsion, trace or no balls are formed. When added silica sol to the emulsion and dispersed it by stirring, easily leads to uneven dispersion, cause reunite seriously and trace balls are formed; when granulating by continuous high speed stirring, gel beads with low strength were broken; when stirring time is too short, the semi-gel microspheres will deposition, cause fragmentation and reunion; Eventually, using water glass as silicon source, agitation granulation in inverse emulsion, strictly control the pH value, silica sol dispersion mode, stirring speed and time, etc. then drying by pressure or supercritical drying, prepared micron hydrophobic SiO₂ aerogel balls. Its diameter is about 10²0 μm with good dispersion, and its surface area is about 709.3 m2/g, and the average pore diameter is about 11.2 nm. Using dropping ball methods, no matter TEOS or sodium silicate as silica source, when dropping the balls to the kerosene-containing surfactant, all experiments were ended in failure because of the large interfacial tension; when using TEOS as precursor drop the balls in the SiO₂ aerogel platform, no balls form for silica sol spread in the platform; Using water glass as silicon source, combined with self-gel or injecting lye to accelerate gel, drop the balls in the pre-platform, then ambient or supercritical drying, prepared millimeter hydrophobic SiO₂ aerogel ball. Its diameter is about 1² mm, and its surface area is about 734.4 m2/g, and the average pore diameter is about 7.4 nm. All the balls made by these two methods were typical nano-mesoporous materials, which has a good hydrophobicity because it is grafted-CH3 during its preparation, and has a good thermal stability below 1000℃.Secondly, the preparation of SiO₂ aerogel/PS beads was studied. Using Micron SiO₂ aerogel microspheres or SiO₂ aerogel powder as the dispersed phase, BPO as initiator, 5% PVA as suspending agents, Ca₃（PO₄）₂ as a dispersant, strict control the amount of initiator and dispersing agent, stirring speed, heating speed, synthesis temperature and synthesis time, etc. then prepared SiO₂ aerogel/PS beads in air atmosphere. The study found, the size of the composite particle is proportional to the addition of SiO₂ aerogel. The conversion rate of St is firstly increased and then decreased with the increase of stirring speed, and reaches the maximum 87.8% at 200 r/min, and the conversion rate of St is inversely proportional to the addition of SiO₂ aerogel.