Viktor Tokarev
Lviv Polytechnic National University,Ukraine
Title: Hydrogel polymer matrices for in-situ synthesis of semiconductor nanoparticles
Biography
Biography: Viktor Tokarev
Abstract
The specially designed reactive copolymers with pendant peroxide groups (RPC) and poly(ethylene glycols) of various molecular weights (PEG) were used for obtaining the cross-linked reactive polymer matrices useful for in-situ synthesis of semiconductor nanocrystals. The networks in the polymer matrices were formed by annealing the mixtures of RPC and PEG owing to both a sequence of radical reactions (decomposition of the RPC peroxide groups, hydrogen abstraction, and recombination reactions) and acylation reactions yielding ester linkages between macromolecules of RPC and PEG. The network formation was accompanied with an increase in the matrix hydrophobicity owing to transformation of some hydrophilic groups in macromolecules of the initial polymes RPC and PEG. The cross-linked polymer matrices obtained with nanopores of controlled size can serve as nanoreactors for in-situ synthesis of semiconductor nanocrystals (NCs).
The new method for obtaining the nanocomposites based on the cross-linked polymer matrices with embedded undopped and dopped semiconductor nanocrystals of controlled size was developed. The size of NCs and the nanocomposite optical properties depended on several factors, among which the most important were the nature of RPC, MW of PEG, PEG/RPC ratio, concentration of precursor (metal salts). The notable benefit of the method developed is feasibility of obtaining the nanocomposites with a high concentration of NCs (up to 20 wt% and more). It is very important that, in spite of high NC concentrations, the nanocomposites were transparent, not opaque evidently because of formation of NCs inside of the swelled polymer gel matrix that avoids their aggregation.