One-pot Synthesis Of Silica-coated Metal Nanoparticles And Their Application In Optical Limiting Materials

Noble metal nanoparticles have become the focus of research in laser protection materials due to their ultra fast nonlinear optics response.The surface plasmon resonance of Au and Ag nanoparticles can be adjusted by the morphology of the particles;Therefore,it can be developed as an optical limiting material against tunable laser.The key to the development of solid optical limiting devices based on Au and Ag nanoparticles is the successful transfer of metal nanoparticles from aqueous phase to organic phase and their doping into hydrophobic polymers.Due to the thermodynamic instability,metal nanoparticles tend to accumulate irreversibly during the transfer process,and the core-shell structure can effectively eliminate the phenomenon of aggregation.As coating material,SiO₂ has high stability,chemical inertness,controllable porosity and optical transparency.Therefore,Si O2 coating is an effective method to disperse metal nanoparticles into hydrophobic polymers.However,most of the synthesis of Si O2-coated metal nanoparticles involves several steps,which requires a lot of time.Therefore,a simple one-pot synthesis method is of great significance for the development of optical limiting materials based on Au and Ag nanoparticles.1.Au@SiO2 nanoparticles were prepared through reduction of chloroauric acid by formaldehyde by one-pot method with tetraethyl orthosilicate?TEOS?as silicon source,cetyltrimethylammonium bromide?CTAB?as stabilizer and mesoporous structure template under alkaline conditions.The UV-vis absorption spectra of Au nanoparticles before and after silica coating showed the coating could finish in 60 min and the absorption peaks wavelength of the Au@SiO2 had more red shift with more TEOS dosage.Tansmission electron microscope?TEM?Au@SiO2 was carried out.The results showed that and the ratio of the thickness of SiO2 shell to the diameter of Au core increased along with the TEOS dosage?2.Ag@SiO₂ nanoparticles were prepared through reduction of AgNO₃ by formaldehyde by one-pot method with TEOS as silicon source,CTAB as stabilizer and mesoporous structure template.The influence of TEOS dosage on the wavelength of UV-vis absorption peak of Ag nanoparticles before and after Si O2 coating with coating was studied.The results show the absorption peak of the Ag@SiO₂ had more blue shift for more TEOS dosage.TEM of the Ag@SiO2 indicated that the ratio of the thickness of SiO₂ shell to the diameter of Ag core also increased with the dosage of TEOS.3.Silver nanoparticles-organic silicon hybrid rubber materials with different Ag@SiO₂ content were prepared,and the optical limiting properties of silver nanoparticles-organic silicon hybrid rubber materials under 532 nm nanosecond laser were studied,the results show that silver nanoparticles-silicone hybrid rubber materials have the same excellent properties as Ag@SiO2 nanoparticles optical limiting materials prepared by multi-step synthesis method.The results showed that one-pot synthesis could successfully prepare silver nanoparticles-silicone hybrid rubber optical limiting materials.