Influence of QD-PMMA interface modification on optical and mechanical properties of composite films

R. Abozaid, V. Radojevic, I. Radovic, Z. Lazarevic, N. Romcevic, D. Sevicc, M. Rabasovic
University of Belgrade, Faculty of Technology and Metallurgy,

Keywords: polymer nanocomposites, core-shell quantum dots, PMMA


Processing and characterization of polymer nanocomposites based on poly (methyl methacrylate) (PMMA) matrix with embedded core-shell CdSe/ZnS quantum dots were presented in this work. The aim is to preserve the optical activity of QD`s in nanocomposite processing with improved mechanical properties. The modification of QD/PMMA interface was achieved with 3- Mercaptopropyltrimethoxysilane (MPTMS). Nanocomposites were processed by solution casting. The samples of pure PMMa, and composites with unmodified and silane modified QD were processed. FTIR analysis revealed modification of QD with silane and characteristic bonding with PMMA matrix. In this case of nanocrystal with relatively small dimension, in the frequency range between longitudinal optical phonon frequency (ω_LO) and transversal optical phonon frequency (ω_TO), a new mode known as a surface optical phonon (SOP) mode appears. Raman spectrum confirms a presence of alloyed layer at the core-shell interface. Position surface optical phonon (SOP) mode is moving towards larger wavelengths with increases filling factor. Time-resolved laser induced fluorescence measurements confirmed slight blue shift in QD/PMMA composite without interface modification, while there was a slight red shift with modified particles. Oxidation effects in quantum dots were removed with the use of PMMA as a host, and the core remained active, which was confirmed with FTIR analysis and time-resolved laser induced fluorescence measurements