Surface modification and functionalization through self-assembly and graft polymerization

A functionalization with an aniline monolayer of a modified glass or glass fiber surface, followed by the surface grafting of polyaniline was used to prepare a conductive surface. A self-assembled bromopropylsilane monolayer was first generated and then further functionalized by its reaction with aniline, which substituted the bromide atoms of the silane chain. Further, the tethered aniline molecules were used as active sites for the graft polymerization of polyaniline (PANI) on the surface. The surface conductivity of the modified surface using this method was 1--2 orders higher than the usual value of the bulk polyaniline. In addition, a novel strategy of combination of surface graft polymerization of aniline and photo-patterned self assembly monolayer (SAM) was used to generate a well-defined pattern of conductive polyaniline on a Si(100) surface. A self-assembly of phenylsilane monolayer was first photo-patterned under an W laser at 263nm through a lithographic mask which was further used for the graft polymerization of aniline after a series of chemical reaction to prepare a patterned conductive PANI layer. Microscopy images revealed a compact grafted PANI and a high edge acuity of the pattern. The present method provides a new strategy for the generation of a pattern of conductive polymers via graft polymerization.; The above method also extended to coating conductive polyaniline on luminescent silicon nanoparticles. After the surface modification and acid doping of the PANI, the coated particles exhibit a bulk electrical conductivity near 10 -2 S/cm. The silicon nanoparticles coated with PANI through the self-assembly method form a dense protect layer on the particle surface and greatly improved silicon nanoparticle's photoluminescence stability. In addition, experiments regarding the electromagnetic interference (EMI) shielding of the PANI grafted Si-nanoparticles are also included in the research work to demonstrate the surface conductive effect of grafted PANI.; Water-solubility with good PL stability in water solution is required for the nanocrystals to be employed for biological applications. UV induced graft polymerization was also used to prepare a stable aqueous luminescent polymer coated silicon nanoparticles solution by grafting water soluble poly(ethylene glycol) acrylate (PEGA) or poly(acrylic acid) (PAAc) on their surface. By grafting a water soluble polymer on the particles, the aggregation of Si nanoparticles could be thus avoided and a stable, clear aqueous solutions could be obtained. Following that, the PAAc modified silicon nanoparticle with high photoluminescence stability was first used as biological labels for cell imaging. (Abstract shortened by UMI.)...