Preparation Of Novel Nano-silica Fluids And Their Composites

Nanofluids with liquid-like behavior is a long-chain organic molecules modifiedsingle-phase nanoparticles system. The long-chain organic molecules as nanoparticles’"shell"act as the "solvent" of the whole system, thus provides the fluidity of liquid at roomtemperature for the system, while the nanoparticles act as the "core" can maintain theirproperties and nano-structures. In this paper two categories of nano-SiO2fluids behavioringlike liquid was synthesized through ionic chemically functionalization on the basis ofsummarizing the research of nanomaterials with liquid-like behavior. Their application incomposite materials and the overall performance of the composite system was further studied.（1）Nano-SiO2-based fluids contains a large number of hydroxyl groups(NSiF-Hs)were obtained via surface grafting silane and aminated into ammonium salt and further ionexchanged with PEG sulfonate. IR spectroscopy,1H NMR and other characterizations werecarried out to confirm the structure of the NSiF-Hs; TGA tests showed NSiF-Hs’ silica massfraction is14.76%and showed no signs of decomposition under200oC; rheologicalcharacterization tests proved NSiF-Hs have rheological behavior as fluid in the test range of5-25oC; TEM electron microscopy characterization confirmed NSiF-Hs have the “core–shell”structure; AC impedance tests showed the conductivity of the NSiF-Hs is up to9.16×10-6S/cm at25oC; novel polyurethane composite materials were obtained by applying theNSiF-Hs into polyurethane systems, the strength and elongation at break have improved greatin a certain range.（2）The NSiF-Hs were applied into PEO/LiClO4polymer electrolyte membranes toobtain novel PEO composite electrolyte membrane. IR, XRD and SEM characterizationsconfirmed the addition of the nano-SiO2nanofluids have reduced the crystallinity of the PEOcomposite electrolyte systems; DSC characterization for crystallinity quantitative calculationsshowed that the composite systems reduced its crystallinity from63.8%to20.2%; TGAshowed that the initial decomposition temperature of the system increased from177oC to264oC; AC impedance test indicated that the conductivity of the composite systems improvedfrom1.75×10-5S/cm to5.39×10-5S/cm; the stress and elongation at break of the composite systems has also been improved.（3） Nano-SiO2fluids/epoxy composites were synthesised by adding anotherself-synthesised SiO2nanofluids（NSiF-Ims） into the epoxy system，TGA characterizationshowed the thermal decomposition of the systems were above400oC, hydrophilicityincreaseed and Tg decreased of as the content of the NSiF-Ims increased; extraction methodwas adopt to exchange down the PEG chain segments.,SEM characterization showed that thefinal epoxy resin film had porous structures and are potential materials for catalyst andgas-absorbent.