Design And Preparation Of Nonlinear Optical Functional Materials Based On Polyaniline

Non-linear optical materials have become a research focus because of their excellent performance in real-time information storage,optoelectronic modulation and laser protection.These materials have played an important role in people’s daily life and national defense industry.Currently,the focus of research is mainly on the interaction between intense laser and materials,so as to explore the internal structure,composition and the change of the optical properties of the materials which caused by the nonlinear polarization phenomenon.The purpose of the study is to obtain functional materials with superior nonlinear properties.Porphyrin and their derivatives are a class of compounds which have largeπconjugated electrons.What’s more,they also have extensive applications in biochemistry,materials science and other fields.Polyaniline（PANI）and graphene oxide（GO）are popularly studied due to their excellent nonlinear optical properties and low manufacturing cost.Based on the above research background,we designed and synthesized PANI-and GO-based nanohybrids,which are covalently functionalized with different porphyrins.In order to confirm the formation of nanohybrids,these materials are also characterized by a variety of test methods.The third-order nonlinear optical properties are also measured by Z-scan technique,and the optical limiting mechanism is briefly explored.In the second chapter,metalloporphyrins(MTpp,M=Sn²⁺,Zn²⁺,Co²⁺)covalently decorated with PANI(PANI-MTpp,M=Sn²⁺,Zn²⁺,Co²⁺)were synthesized through a covalently bonded method.Fourier-transform infrared,X-ray photoelectron spectroscopy,Raman spectroscopy,thermogravimetric analysis suggest successful preparation of hybrid materials.Effective electron or energy transfer was proved by Ultraviolet-visible absorption and fluorescence spectroscopic techniques.The NLO performances of the as-prepared samples were studied by the Z-scan technology at 532 nm with nanosecond laser pulses,the results displaying that the chemical nanohybrids exhibit enhanced nonlinear optical properties in comparision with those of the constituent PANI or metalloporphyrins.In the third chapter,on the basis of the above-mentioned binary nanohybrid materials,a novel ternary nanohybrid material（GO-PANI-SnTpp）composed of SnTpp,PANI and GO was further synthesized.Infrared spectroscopy,Raman spectroscopy,comprehensive thermal analysis and scanning electron microscopy have preliminarily validated the successful preparation of GO-PANI-SnTpp ternary nanohybrids.The steady-state fluorescence spectrum analysis showed that the fluorescence spectrum of the hybrid materials have a significant quenching effect relative to the single porphyrin compound and the binary hybrid material.Combined with UV-Visible absorption spectroscopy results,electron or energy transfer effects are present in the ternary nanohybrid materials.The NLO properties of the three nanohybrids are measured by Z-scan technique at 532 nm with nanosecond laser pulse,the results indicating that ternary nanohybrid materials have superior nonlinear optical response than the porphyrin alone and the binary nano-hybrid materials（PANI-SnTpp）.In the fourth chapter,three kinds of metal-porphyrins were covalently functionalized on the surface of GO to obtain three kinds of ternary nanohybrid materials（GO-PANI-SnTpp,GO-PANI-ZnTpp,GO-PANI-CoTpp）.Infrared and Raman spectroscopy illustrated the successful preparation of the ternary nanohybrid materials.UV-Vis absorption spectroscopy,steady-state fluorescence spectroscopy and other methods proved that there is obvious electron or energy transfer within the ternary nanohybrid materials.Z-scan showed that the ternary nanohybrid materials possess superior nonlinear optical properties than the PANI monomer and the binary nanohybrid materials.