Interface-directed sol-gel: direct fabrication of the covalently attached ultraflat inorganic oxide pattern on functionalized plastics

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., TiO 2 . surface patterning, silicon oxide, sol-gel, polymer surface modification, functional coatings

Non-Calcium Inorganic Materials Fabrication by Surface-Immobilized Organic Molecular Template

“…, and the controlling on the deposition thickness was facilely achieved by changing TEOS concentration, as plotted in (b) and visualized in (c). Reproduced from (Yang et al, 2010). Copyright from Science in China Chemistry.…”

“…As a result, no discernible difference could be told between pristine BOPP and BOPP-OH/SiO x films, after direct observation by eyes on the characters ("BUCT") behind two kinds of films. Reproduced from (Yang et al, 2010). Copyright from Science in China Chemistry.…”

“…Optical images of patterned SiO x layer on BOPP-OH surface fabricated by adhesive tape peeling (left) and ultrasonic agitation (right). Reproduced from (Yang et al, 2010). Copyright from Science in China Chemistry.…”

“…The profile intensity on selected region (inset picture) showed around 3:1 signal-to-background ratio could be obtained by this type of protein immobilization. Reproduced from (Yang et al, 2010). Copyright from Science in China Chemistry.…”

“…Therefore, our aim is to extend the content of the biomineralization mediated by surface-immobilized organic molecular template from classical calcium to a wide range of inorganic and metal materials through rationally engineering surface molecular template from small functional groups to macromolecules. We for the first time initiated this program in 2005 for the synthesis of silver nanoparticles mediated by surface-immobilized peptides, and after that, a series of researches in this field were reported to exploit the mediation ability of surface-immobilized organic molecule at different molecular scale, including small functional groups for the synthesis of titanium, zinc and silicon oxide films 2008;Gan et al, 2010), oligomer-grade peptides for the synthesis of gold, silver, platinum nanoparticles and superstructures 2008;Wang et al, 2007;Li et al, 2007) and macromolecular brush for the fabrication of zinc oxide quantum dot and organic/inorganic hybrid nanocomposite film (Zou et al, 2009).…”