Study On The One-step Preparation Of Hybrid SiO₂ Nanoparticles And Its Functionalization

The SiO₂ nanoparticle(SiO₂ NP)is a very important nanomaterial in modern technology.However,conventional SiO₂ NPs can hardly meet demands in applications due to the absence of functional groups.To overcome this problem,SiO₂ NP is usually modified with organic functional moieties,called hybrid NP,so that it can be applied in catalysis,chemical sensor,fluorescence imaging and so on more conveniently.In this research,two types of SiO₂ NP with different functional moieties on the surface(as well as in the core)are synthesized by hydrolyzing two silicon sources together in one step.The size distributions and morphologies of the particles are studied by varying synthetic parameters.The hybrid NP is also selected for surface grafting polymerization and fluorescence molecules doping,and the major results and conclusions are as follows,(1)When hydrolyzing tetraethyl orthosilicate(TEOS)and 3-(methacryloyloxy)propyl trimethoxysilane(MPS)simultaneously,gelation happened and no NP can be obtained,because the hydrolysis of MPS is much faster than TEOS,and a crosslinked network is resulted.When MPS is replaced by 3-(methacryloyloxy)propyl triethoxysilane(EPS)which has lower hydrolyzing rate,hybrid silica NP is achieved successfully.(2)Silica NP hybridized with methacrylate group(SP₁)and thiol group(SP₂)are prepared successfully.SP₁ is prepared by using TEOS and EPS,and the size distribution of SP₁ is ranged from 60 to 560 nm;SP₂ is prepared by using 3-mercaptopropyltriethoxysilane(MTS)with size distribution from 54 to 210 nm.The effects of ratio between silicon sources molecules,water and catalyst contents and other factors in the preparation are investigated in detail.The particle size,morphology and hybrid organic moieties are characterized by dynamic light scattering(DLS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),thermogravimetric analysis(TGA)and Fourier transform infrared spectroscopy(FTIR).(3)SP₁ NP with sizes about 80 nm and 200 nm are selected for surface reversible addition-fracture chain transfer(RAFT)grafting polymerization.The content of RAFT reagent introduced onto the surface of NP was determined by UV-vis spectrophotometer.The polymer/hybrid SiO₂ nanoparticles with core-shell structure are obtained with size at about 250 nm and 470 nm,respectively.(4)Aggregation-induced emission(AIE)molecule is synthesized,and then introduced into the silica hybrid NP via silane chemical modification and cocondensation.The resulting hybrid NP showed stable fluorescent in 479 nm,when excited at 365nm...