title: Two substrate-confined sol-gel coassembled ordered macroporous silica structures with an open surface.
abstract: A sol-gel cooperative assembly method was demonstrated for the fabrication of inverse opal films with an open surface. In this method, a sol-gel silicate precursor was cooperatively assembled into the interstitial spaces of microspheres at the same time when polystyrene templates formed in between two desired substrates. Silica inverse opals with a three-dimensional ordered macroporous (3DOM) structure were obtained after selective removing the colloidal templates by calcination. The open surfaces with a high degree of interconnected porosity and extremely uniform pore size were characterized by scanning electron microscope (SEM). Optical transmission spectra reveals the existence of considerable deep band gaps of up to 70% and steep band edges of up to 6%/nm in the [111] directions of the 3DOM silica samples. A little shrinkage confirmed by transmission spectra is not larger than 3%, in consistent with the results measured by SEM, which revealing the sufficient and compact infiltration into the interstitial spaces by our confined sol-gel coassembly method. With different incidence angles, the positions of pseudogaps can be easily tuned in the wide range from 720 nm to 887 nm, agreed well with the calculated values by the Bragg law. All the results prove that the sol-gel coassembly method with two substrates confinement is a simple, low cost, convenient and versatile method for the fabrication of silica inverse opals without overlayers in large domains.
authors.affiliation: School of Physics and Technology, Nanjing Normal University, Key Laboratory on Opto-Electronic Technology of Jiangsu Province, Nanjing 210046, China.
authors.forename: Wenhua
authors.initials: W
authors.lastname: Guo
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.forename: Wei
authors.initials: W
authors.lastname: Xia
authors.forename: Lihua
authors.initials: L
authors.lastname: Dai
mesh_terms: D003102:Colloids / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D015394:Molecular Structure; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D003102:Colloids; D005782:Gels; D011137:Polystyrenes; D012822:Silicon Dioxide