Photoinduced High-Quality Ultrathin SiO 2 Film from Hybrid Nanosheet at Room Temperature

Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Journal of the American Chemical Society (Impact Factor: 12.11). 10/2008; 130(36):11848-9. DOI: 10.1021/ja803852w
Source: PubMed


The paper describes a flexible approach to building up high-quality ultrathin SiO2 films under deep UV light irradiation at room temperature. The ultrathin hybrid nanosheet possessing polyoctahedral silsesquioxane (POSS) has been designed to prepare densely packed ultrathin POSS films by the Langmuir-Blodgett (LB) technique. The LB technique enables POSS to have a multilayered structure with nanoscale precision. The films' hardness and modulus changed considerably from 0.1 and 2.6 GPa to 1.7 and 32.2 GPa, respectively, after deep UV light irradiation. Subsequent FTIR measurements revealed that the organic components were removed completely and that the POSS cage structure turned to an Si-O-Si network structure. X-ray photon spectroscopy also confirmed high-quality SiO2 formation with no suboxides.

8 Reads
  • Source
    • "The monolayer is easily transferable on solid supports as Y-type LB films over 700 layers.[2] A diverse range of molecules have been successfully incorporated in ultrathin polymer films at the monolayer level: e.g., organometallic complexes,[3] aromatic hydrocarbons,[4] [5] [6] redox active groups,[7] [8] thermosensitive groups,[9] nonlinear optical active groups,[10] [11] [12] ferroelectric polymers,[13] and polyhedral oligomeric silsesquioxane.[14] [15] The ultrathin polymer films act as a nanoruler manipulating nanomaterials systematically with nanoscale precision.[12] [16] After demonstrating the versatility of acrylamide-based polymer LB films in terms of surface coating at the nanometer level, we designated polymer LB films as "polymer nanosheet".[17] "
    [Show abstract] [Hide abstract]
    ABSTRACT: The paper presents luminescence properties of platinum porphyrins embedded in ultrathin polymer Langmuir-Blodgett (LB) films (nanosheets). We prepared amphiphilic copolymer of platinum porphyrin with N-dodecylacrylamide (p(DDA/PtTPP)). The copolymer p(DDA/PtTPP) with 6mol% PtTPP content took a stable monolayer formation at the air-water interface. Luminescent p(DDA/PtTPP) nanosheets were successfully assembled on solid substrates by the vertical dipping method. The luminescence intensity as a function of the number of layers revealed that platinum-porphyrin is effectively quenched by molecular oxygen for multilayered p(DDA/PtTPP) nanosheets with more than ten layers. Atomic force microscopy revealed that the p(DDA/PtTPP) nanosheets had relatively rough surfaces, leading to high surface-tovolume ratio. The oxygen sensitive polymer nanosheet multilayers enables us to monitor dissolved oxygen concentration in water.
    Preview · Article · Apr 2014 · International Journal of the Society of Materials Engineering for Resources
  • [Show abstract] [Hide abstract]
    ABSTRACT: For plastic electronics and optics, the fabrication of smooth, transparent and stable crack-free inorganic oxide films (and patterning) on flexible polymeric substrates with strong bonding strength and controllable thickness from nanometers to micrometers is a key but still remains a challenge. Among versatile inorganic oxides, silica oxide film as SiO x is especially important because this semiconductor material could provide crucial properties in devices or serve as a base layer for further multilayer construction. In this paper, we describe a new interface-directed sol-gel method to fabricate flexible high quality silicon oxide film onto commodity plastics. The resulting crack-free silica film has strong covalent bonding with polymer substrates, homogeneous morphology with ultralow roughness, highly optical transparency, tunable thickness from nm to μm, and easy patterning ability. Such fabrication strategy relies on a novel photocatalytic oxidation reaction by photosensitive ammonium persulfate (APS), which is able to fabricate highly reactive hydroxyl monolayer surface on inert polymeric substrates. This kind of hydroxylated surface could serve as nucleation and growth sites to initiate surface sol-gel process. As a result, well-defined SiO x film deposition (gelation) occurs, and patterned hydroxylation regions could be easily utilized to induce the formation of patterned oxide film arrays. Our strategy also excludes the requirements of clean room and vacuum devices so as to fulfill low-cost and fast fabrication demands. Two application examples from such high quality SiO x layer onto plastics are given but should not be limited within these. One is that oxygen permeation rate of SiO x deposited polymer film decreases 25 times than pristine polymer substrate, which is good for the potential packaging materials. The other one is that silanization monolayer, for example, 3-aminopropyltriethoxysilane (APTES), could be successfully constructed onto silica layer through classical silanization reaction, which is applicable for many potential purposes, for instance, proteins could be accordingly immobilized onto plastic support with effective signal-to-background ratio. Moreover, we further demonstrate that this interface-directed sol-gel strategy is a general method which could be successfully extended to other high quality oxide film fabrication, e.g., TiO2.
    No preview · Article · Jan 2010 · Science China-Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new generation of plastic transistors consisting primarily of light and flexible organic materials requires new fabrication methods which combine low-temperature, solution-phase processing with precise control in the nanometer range over the component dimensions. Ultrathin silicon oxide films, which serve as gate dielectric layers in these transistors, were recently grown at room temperature from polymer precursor films by a novel layer-by-layer deposition/oxidation process.
    No preview · Article · Mar 2009 · Angewandte Chemie International Edition
Show more