Facile One-pot Synthesis of Multi-functional Hybrid Silica(MHS) Particles and Their Self-assembly to 3-Dimensional Structure.

초록

Multifunctional hybrid particles have recently emerged as a new approach for smart materials in nano, bio, and material sciences. A variety of preparation methods for multi-functional hybrid particles have been developed, including core shell synthesis, layer-by-layer technique, multi-block copolymer emulsification method, surface modification, and etc. Multi-functional particles can perform multiplex tasking that enables the applications which single functional particles cannot achieve for instance, target-selective multi-color imaging and 3-dimensional building block for photonic crystals and integrated circuits. Therefore, the development of a simple and efficient preparation method for particles with various types of functionalities is of great importance in order to be used in wider applications. In this work, we introduce a facile preparation method for multi-functional hybrid silica (MHS) particles by self emulsion process without using any surfactant. Droplets of mixed organo-silane monomers with phenyl, amine, and thiol functionalities were initially formed under a strong acidic condition and then homogenous MHS particles were obtained through condensation reaction in a basic condition. The MHS particles were tagged with two different reactive dyes, fluroescamine for amine functionality and rhodamine red for thiol functionality, so that the distribution of functionalities on particles was investigated. In addition, amine functionality was converted to carboxyl acid group by chemical reaction with glutaric anhydride so as to give another functional group on MHS particles. Self-assembly to 3-dimentional structure demonstrated a potential ability of MHS particles for building block through acid-base reaction between two MHS particles with different size and functionalities (one with -COOH (1.4 μm) and another with -NH2 (200 nm)). We also applied self-assembly of MHS particles to patterning on amine functionalized substrate. The acid-base reaction between amine groups on the glass surface and carboxylic groups on the surface of MHS particles leads to the formation of the patterned assembly of MHS particles on the glass.