Key words: polymer nanocomposite, supercritical fluid impregnation, nanocrystalline silicon, photoluminescence
With the use of supercritical carbon dioxide (SC-СO2) a process of matrix immobilization of photoluminescent silicon nanocrystals (nc-Si) in polytetrafluoroethylene microparticles (mp-PTFE) is implemented, which leads to the formation of photoluminescent nanocomposite mp-PTFE/nc-Si containing ~103 ÷104 of nc-Si in one PTFE particle (1—2 microns in size). This process is based on the effect of polymer swelling in SC-СO2, efficient transport of nanoparticles into internal free volume of polymer with SC-СO2, and shrinkage of nanocomposite after the release of СO2 thus preventing their subsequent agglutination. Particles of nc-Si photoluminescent in the visible spectrum range were synthesized from silicon suboxide powder (SiOx, x ~ 1) heated at temperatures from 25 °C to 950 °C and next etched in concentrated hydrofluoric acid. The hydrosilylation procedure was used to attach 1-octadecene molecules to the surface of nc-Si. As a result, the photoluminescence intensity of nc-Si increased substantially. According to TEM images and small angle X-ray diffraction results, the maximum size of nc-Si particles did not exceed 5 nm and 7 nm respectively, and the core of these nanoparticles consisted of crystalline silicon. The structure and spectral properties of the initial nc-Si particles and synthesized photoluminescent nanocomposite mp-PTFE/nc-Si microparticles were studied.
doi:10.1134/S1990793110070171