Nanoparticles and nanocomposites in rf plasma

The use of low pressure radio-frequency (rf) plasma for nanoparticle formation and the deposition of thin film on particulate substrates are reported. Plasma polymer particles are synthesized in a capacitively-coupled Ar/monomer discharge at rf power of 15-30 W. A variety of particle structures are observed, including monodispersed nanospheres and liquid-like viscous nano-droplets. Styrene in particular is observed to produce hollow nanospheres. By manipulating the process parameters, films of plasma polymers can be deposited onto suspended submicron particles. We take advantage of the electrostatic trapping of "dusty plasma" to suspend small particles in plasma for extended periods of time until the desired coating thickness is achieved. Sub-micron silica particles introduced into a low pressure rf Ar/monomer plasma are coated with film of thickness ranging from 2 to 70 nm.