7 research outputs found
Fluorinated Raspberry-like Polymer Particles for Superamphiphobic Coatings
Raspberry-like (RB) polymer particles were prepared, fluorinated, and cast onto glass plates to yield highly water- and oil-repellant superamphiphobic particulate coatings. To procure the RB particles, glycidyl-bearing 212 and 332 nm particles (abbreviated as <i>s</i>-GMA and <i>l</i>-GMA, respectively) were first prepared via surfactant-free free radical emulsion polymerization. Reacting the glycidyl groups of the <i>l</i>-GMA particles with 2,2âČ-(ethylenedioxy)ÂbisÂ(ethylamine) (EDEA) produced large amine-functionalized particles (<i>l</i>-NH<sub>2</sub>). The <i>l</i>-NH<sub>2</sub> particles were then reacted with an excess of the <i>s</i>-GMA particles to create RB particles. For surface fluorination, the residual glycidyl groups of the smaller <i>s</i>-GMA particles surrounding the central <i>l</i>-NH<sub>2</sub> core of the RB particles were first converted to amino groups by reaction with EDEA. The purified amino-bearing particles were subsequently reacted with an excess of a statistical copolymer polyÂ(2-(perfluorooctyl)Âethyl methacrylate-<i>co</i>-glycidyl methacrylate), PÂ(FOEMA-<i>co</i>-GMA). Casting these particles onto glass plates yielded particulate films that exhibited static contact angles of 165 ± 2°, 155 ± 3°, 152 ± 4°, and 143 ± 1° and droplet rolling angles of <1 °, <1 °, 7 ± 2°, and 13 ± 2° for water, diiodomethane, corn-based cooking oil, and hexadecane droplets, respectively. These results demonstrated that this practical bottom-up approach could be used to produce superamphiphobic coatings
Clear Antismudge Unimolecular Coatings of Diblock Copolymers on Glass Plates
Two polyÂ[3-(triisopropyloxysilyl)Âpropyl
methacrylate]-<i>block</i>-polyÂ[2-(perfluorooctyl)Âethyl
methacrylate] (PIPSMA-<i>b</i>-PFOEMA) samples and one polyÂ(perfluoropropylene
oxide)-<i>block</i>-poly-[3-(triisopropyloxysilyl)Âpropyl
methacrylate] (PFPO-<i>b</i>-PIPSMA) sample were synthesized,
characterized, and used to coat glass plates. These coatings were
formed by evaporating a dilute polymer solution containing HCl, which
catalyzed PIPSMAâs solâgel chemistry. Polymer usage
was minimized by targeting at diblock copolymer unimolecular (brush)
layers that consisted of a solâgelled grafted PIPSMA layer
and an oil- and water-repellant fluorinated surface layer. Investigated
is the effect of varying the catalyst amount, polymer amount, as well
as block copolymer type and composition on the structure, morphology,
and oil- and water-repellency of the coatings. Under optimized conditions,
the prepared coatings were optically clear and resistant to writing
by a permanent marker. The markerâs trace was the faintest
on PFPO-<i>b</i>-PIPSMA coatings. In addition, the PFPO-<i>b</i>-PIPSMA coatings were far more wear-resistant than the
PIPSMA-<i>b</i>-PFOEMA coatings
Enhanced Hematite Water Electrolysis Using a 3D Antimony-Doped Tin Oxide Electrode
We present herein an example of nanocrystalline antimony-doped tin oxide (nc-ATO) disordered macroporous âinverse opalâ 3D electrodes as efficient charge-collecting support structures for the electrolysis of water using a hematite surface catalyst. The 3D macroporous structures were created <i>via</i> templating of polystyrene spheres, followed by infiltration of the desired precursor solution and annealing at high temperature. Using cyclic voltammetry and electrochemical impedance spectroscopy, it was determined that the use of this 3D transparent conducting oxide with a hematite surface catalyst allowed for a 7-fold increase in active surface area for water splitting with respect to its 2D planar counterpart. This ratio of surface areas was evaluated based on the presence of oxidized trap states on the hematite surface, as determined from the equivalent circuit analysis of the Nyquist plots. Furthermore, the presence of nc-ATO 2D and 3D âunderlayerâ structures with hematite deposited on top resulted in decreased charge transfer resistances and an increase in the number of available active surface sites at the semiconductorâliquid junction when compared to hematite films lacking any nc-ATO substructures. Finally, absorption, transmission, and reflectance spectra of all of the tested films were measured, suggesting the feasibility of using 3D disordered structures in photoelectrochemical reactions, due to the high absorption of photons by the surface catalyst material and trapping of light within the structure