The present study deals with the one-pot synthesis of acrylate copolymers/silica latexes through the use of simultaneous radical polymerization of acrylic monomers and a silica sol-gel precursor. In presence of 3-methacryloxypropyltrimethoxysilane (γ-MPS) and 3-aminopropyltriethoxysilane (APTS), compatibility of acrylate chains to the silica species was improved by the chemical bonds as revealed by Fourier transform infrared spectroscopy (FTIR) analysis. Transmission electron microscopy (TEM) demonstrated the successful formation of p(acrylic acid-co-2-ethylhexyl acrylate)/silica nanohybrids with core-shell morphology. The nanohybrids have been used to modify a glassy carbon electrode (GCE). Cyclic voltammetry and electrochemical impedance spectra were utilized to investigate the properties of the modified electrode in a 1.0 m KCl solution that contained 1.0 mm K4[Fe(CN)6]/K3[Fe(CN)6], and the interface properties of electrode surfaces. The result showed a dramatic decrease in redox activity as compared to the bare GCE electrode. This revealed a slight increase in electron transfer resistance and the conductivity of the copolymer oligomers and silica species in the hybrid nanostructure. All the electrochemical results illustrated that the p(acrylic acid-co- 2-ethylhexyl acrylate)/silica nanohybrids could immobilize the selective analytes on the electrodes, which had electrochemical catalytic activity. The barrier properties of the hybrid films were also examined via ultraviolet (UV) absorption capacity of the films. It could be concluded that the adsorption capacity was a function of the silica content and uniform dispersion of the nanoparticles in the resultant films.
An appropriate approach has been used for the preparation of silica/P(MMA-co-St) hybrid nanoparticles through converting previously prepared inverse miniemulsions into a direct miniemulsion and consequently, using the droplet nucleation polymerization technique. In the early stage of the procedure, silica particles were synthesized from TEOS in the presence of NH 4 OH or HCl as a catalyst through a base or acid-catalyzed sol-gel process. TEOS, ethanol and tirmethoxyvinylsilan were mixed in MMA:St (50:50) to create the inverse miniemulsion I, similarly CTAB, NH 4 OH/HCl and distilled water were dispersed into MMA:St (50:50) and called inverse miniemulsion II. Then, the two mentioned inverse miniemulsions were emulsified in water to achieve direct miniemulsion. The nature of the catalyst and TEOS concentration varied, for the aims of investigation, their effect on the morphology and size of hybrid nanoparticles. This route provided a unique process for silica/polymer hybrid nanoparticles production, avoiding organic solvents. Transmission electron microscopy micrographs revealed that, the morphology of the hybrid nanoparticles can be controlled by the nature of the catalyst.
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