Preparation of Quaternary Ammonium Organosilane Functionalized Mesoporous Thin Films

• Published in: Langmuir 2002-02, Vol.18 (4), p.972-974
• Main Authors: Wong, Eva M, Markowitz, Michael A, Qadri, Syed B, Golledge, Stephen L, Castner, David G, Gaber, Bruce P
• Format: Article
• Language: English
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la015623k

The preparation of surfactant-templated periodic mesoporous silica thin films functionalized with N-((trimethoxysilyl)propyl)-N,N,N-trimethylammonium chloride (TMAC) is described. The supramolecular self-assembly of the triblock copolymer, Pluronic 123, served as a template for the formation of these functionalized silane films. In the as-prepared and extracted conditions, the films exhibited the p6 mm type hexagonal mesostructure with a large unit cell (a = 8.5−9.6 nm). Contraction of the films during heat treatment (250 °C for 2 h) reduced the pore spacing perpendicular to the substrate yielding Fm3m pore ordering, confirmed by X-ray diffraction and transmission electron microscopy. Ellipsometry measurements revealed the films to have thickness of ∼400 nm in the as-prepared condition and ∼300 nm in the heat-treated condition, a total shrinkage of ∼25% perpendicular to the substrate. X-ray photoelectron spectroscopy measurements showed the incorporation of the TMAC to be 76−90% of the amount initially added following surfactant extraction.