Preparation of organic-ceramic-metal multihybrid particles and their organized assembly

This paper describes the synthesis and assembly of multihybrid particles having a gold core, silica as an initial shell and polymethylmethacrylate (pMMA) as a second shell (Au@SiO2@PMMA). Multihybrid particles were synthesized in a stepwise manner. First, direct sol-gel coating of silica onto gold nanoparticles was carried out to prepare Au@SiO2 particles. The Au@SiO2 particles were modified with 3-(triethoxysilyl)propyl 2-bromo-2-methylpropanoate (BMPS), which is an initiator for atom transfer radical polymerization (ATRP) of MMA. Finally, bulk ATRP of MMA was conducted using BMPS-coated Au@SiO2 particles. Au@SiO2@PMMA particles formed a closely packed monolayer at the air-water interface. The monolayer can be deposited onto a solid substrate using the Langmuir-Blodgett technique. Atomic force microscopy and scanning electron microscopy images of the deposited film show a uniform and closely packed monolayer film in an area a few tens-of-micrometers in size with no voids. Moreover, a clear Au core, silica shell and pMMA shell structure were observed in a transmission electron microscopy image of the transferred film. It is particularly interesting that the monolayer film shows no clear plasmon absorption of the gold core, as observed in the chloroform solution of the particle. Results show that a thick silica shell masked the monolayer film's plasmon absorption. Polymer Journal (2010) 42, 142-147; doi:10.1038/pj.2009.320; published online 23 December 2009