Synthesis of an optically clear, flexible and stable hybrid ureasilicate matrix doped with CdSe nanoparticles produced by reverse micelles

Optically clear and flexible organiceinorganic hybrid materials doped with CdSe nanoparticles (NPs) were synthesized by a solegel method based on the hydrolysis and condensation reactions of ureasilicate precursors. The CdSe NPs were produced by a colloidal method using reverse micelles and were then transferred to the ureasilicate precursor solution followed by gelation of the mixture using ammonia/ water vapours as catalyst for the solegel process. The influence of the NPs surface in the dispersion of the NPs within the matrix was investigated by the addition of a capping agent with both thiol and siloxane groups (3-mercaptopropyltrimethoxysilane, MPTMS). This capping agent was used in order to improve compatibility and avoid aggregation of the NPs within the matrix and to increase the preservation of the original optical properties of the NPs. The nanocomposites obtained were characterized by absorption spectroscopy, steady-state photoluminescence, time resolved photoluminescence, HRTEM and FTIR spectroscopy. The results obtained showed the influence of the use of MPTMS in the preservation of the original optical properties of the CdSe NPs after their transfer into the ureasilicate matrix. The HRTEM analysis showed the presence of well-dispersed spherical NPs with well-defined lattice fringes. The obtained nanocomposites exhibit high transparency in the visible range as a result of the good dispersion of the NPs within the matrix, showing the potentials of the developed method in the production of composite materials in which the optical properties of the NPs incorporated are crucial to the desired application.Fourier transform infrared spectroscopy (FTIR)This work has been partially supported by the Fundação para a Ciência e a Tecnologia (FCT). L. F. Gonçalves thanks the FCT for research the PhD grant SFRH/BD/38262/2007. The authors gratefully acknowledge the financial support by Centro de Química [project F-COMP-01-0124-FEDER-022716 (ref. FCT Pest-C/Qui/ UI0686/2011)-FEDER-COMPETE] and Centro de Física (Universidade do Minho). The authors would like to thank the Electron Microscope Unit of the Mark Wainwright Analytical Centre at The University of New SouthWales, for scientific and technical support