Nanostructuring of Titania Thin Films by a Combination of Microfluidics and Block‐Copolymer‐Based Sol–Gel Templating

Abstract

Sol-gel templating of titania thin films with the amphiphilic diblock copolymer poly(dimethyl siloxane)-block-methyl methacrylate poly(ethylene oxide) is combined with microfluidic technology to control the structure formation. Due to the laminar flow conditions in the microfluidic cell, a better control of the local composition of the reactive fluid is achieved. The resulting titania films exhibit mesopores and macropores, as determined with scanning electron microscopy, X-ray reflectivity, and grazing incidence small angle X-ray scattering. The titania morphology has three features that are beneficial for application in photovoltaics: 1) a large surface-to-volume ratio important for charge generation with disordered hexagonally arranged mesopores of 25 nm size and a film porosity of up to 0.79, 2) enhanced light scattering that enables the absorption of more light, and 3) a dense titania layer with a thickness of about 6 nm at the substrate (bottom electrode) to prevent short circuits. An optical characterization complements the structural investigation.

On-Chip Fabrication of Carbon Nanoparticle–Chitosan Composite Membrane

“…In addition to the sandwich-type integration and the direct membrane preparation in the chip fabrication process, the in situ method is receiving greater interest. In this method, the membrane can be prepared by using emulsion photopolymerization [17,22,23] , laser-induced phase separation polymerization [24,25] , and laminar flow-based interfacial polymerization techniques [26][27][28][29] . Among these techniques, the first two allow researchers to form membranes with desired thicknesses and at a desired location.…”

Custom‐Made Morphologies of ZnO Nanostructured Films Templated by a Poly(styrene‐block‐ethylene oxide) Diblock Copolymer Obtained by a Sol–Gel Technique

“…[50,51] Pioneering work by Wiesner et al in synthesizing mesoporous titania by using a poly(isoprene-block-ethylene oxide) copolymer template through the sol-gel technique resulted in stable titania networks, even after a high-temperature annealing step. [50,51] Pioneering work by Wiesner et al in synthesizing mesoporous titania by using a poly(isoprene-block-ethylene oxide) copolymer template through the sol-gel technique resulted in stable titania networks, even after a high-temperature annealing step.…”

Low‐Temperature Route to Crystalline Titania Network Structures in Thin Films

“…[30] In addition, the precursor can be processed in purely aqueous solution, thus the particle morphology can be adjusted with the mini-emulsion technique. [35][36][37][38][39] In this article, such a di-block copolymer template, consisting of poly(styrene-block-ethylene oxide) [denoted as P(S-b-EO)], is used in combination with an EGMT-based sol-gel process to produce homogeneous layers with a well-defined network structure. [34] To control the structure of titania films, an amphiphilic diblock copolymer can be utilized as a structure-directing template.…”

“…[34] To control the structure of titania films, an amphiphilic diblock copolymer can be utilized as a structure-directing template. [35][36][37][38][39] In this article, such a di-block copolymer template, consisting of poly(styrene-block-ethylene oxide) [denoted as P(S-b-EO)], is used in combination with an EGMT-based sol-gel process to produce homogeneous layers with a well-defined network structure. Scanning electron microscopy (SEM) measurements reveal the nanostructure of the titania polymer-composite films and the titania films after polymer extraction, whereas the crystal structure is probed with grazing-incidence wide-angle X-ray scattering (GIWAXS).…”