Solution spraying of poly(methyl methacrylate) blends to fabricate microtextured, superoleophobic surfaces

We describe a simple technique to prepare superhydrophobic and superoleophobic microtextured surfaces by spray coating a blend of poly(methyl methacrylate) (PMMA) and the low surface energy molecule 1H,1H,2H,2H-heptadecafluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS, γ[subscript sv] ≈ 10 mN/m) using an air brush with a pressurized nitrogen stream. Scanning electron micrographs show the formation of microtextured surfaces possessing re-entrant curvature; a critical feature for obtaining liquid repellency with low surface tension liquids. The surface morphology can be tuned systematically from a corpuscular or spherical microstructure to a beads-on-string structure and finally to bundled fibers by controlling the solution concentration and molecular weight of the sprayed polymer. The oleophobicity of the resulting structures is characterized by advancing and receding contact angle measurements with liquids of a range of surface tensions.United States. Army Research Office (Contract W911NF-07-D-0004)Air Force Research Laboratory (Wright-Patterson Air Force Base, Ohio). Propulsion DirectorateUnited States. Air Force Office of Scientific Researc

Utilizing Dynamic Tensiometry to Quantify Contact Angle Hysteresis and Wetting State Transitions on Nonwetting Surfaces

Goniometric techniques traditionally quantify two parameters, the advancing and receding contact angles, that are useful for characterizing the wetting properties of a solid surface; however, dynamic tensiometry, which measures changes in the net force on a surface during the repeated immersion and emersion of a solid into a probe liquid, can provide further insight into the wetting properties of a surface. We detail a framework for analyzing tensiometric results that allows for the determination of wetting hysteresis, wetting state transitions, and characteristic topographical length scales on textured, nonwetting surfaces, in addition to the more traditional measurement of apparent advancing and receding contact angles. Fluorodecyl POSS, a low-surface-energy material, was blended with commercially available poly(methyl methacrylate) (PMMA) and then dip- or spray-coated onto glass substrates. These surfaces were probed with a variety of liquids to illustrate the effects of probe liquid surface tension, solid surface chemistry, and surface texture on the apparent contact angles and wetting hysteresis of nonwetting surfaces. Woven meshes were then used as model structured substrates to add a second, larger length scale for the surface texture. When immersed into a probe liquid, these spray-coated mesh surfaces can form a metastable, solid–liquid–air interface on the largest length scale of surface texture. The increasing hydrostatic pressure associated with progressively greater immersion depths disrupts this metastable, composite interface and forces penetration of the probe liquid into the mesh structure. This transition is marked by a sudden change in the wetting hysteresis, which can be systematically probed using spray-coated, woven meshes of varying wire radius and spacing. We also show that dynamic tensiometry can accurately and quantitatively characterize topographical length scales that are present on microtextured surfaces.United States. Air Force Office of Scientific Research (W 911NF-07-D-0004

CCDC 629369: Experimental Crystal Structure Determination

Related Article: S.C.Kettwich, S.N.Pierson, A.J.Peloquin, J.M.Mabry, S.T.Iacono|2012|New J.Chem.|36|941|doi:10.1039/c2nj20922e,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.,Related Article: S.T.Iacono, A.Vij, W.Grabow, D.W.Smith Junior, J.M.Mabry|2007|Chem.Commun.||4992|doi:10.1039/b712976

Innenrücktitelbild: Transparent, Flexible, Superomniphobic Surfaces with Ultra‐Low Contact Angle Hysteresis (Angew. Chem. 49/2013)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101822/1/111112982_ftp.pd

Inside Back Cover: Transparent, Flexible, Superomniphobic Surfaces with Ultra‐Low Contact Angle Hysteresis (Angew. Chem. Int. Ed. 49/2013)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101879/1/111112748_ftp.pd

CCDC 642077: Experimental Crystal Structure Determination

Related Article: S.C.Kettwich, S.N.Pierson, A.J.Peloquin, J.M.Mabry, S.T.Iacono|2012|New J.Chem.|36|941|doi:10.1039/c2nj20922e,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.,Related Article: S.T.Iacono, A.Vij, W.Grabow, D.W.Smith Junior, J.M.Mabry|2007|Chem.Commun.||4992|doi:10.1039/b712976

Superoleophobic Surfaces: Hierarchically Structured Superoleophobic Surfaces with Ultralow Contact Angle Hysteresis (Adv. Mater. 43/2012)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94465/1/5837_ftp.pd

Designing Self-Healing Superhydrophobic Surfaces with Exceptional Mechanical Durability

The past decade saw a drastic increase in the understanding and applications of superhydrophobic surfaces (SHSs). Water beads up and effortlessly rolls off a SHS due to its combination of low surface energy and texture. Whether being used for drag reduction, stain repellency, self-cleaning, fog harvesting, or heat transfer applications (to name a few), the durability of a SHS is critically important. Although a handful of purportedly durable SHSs have been reported, there are still no criteria available for systematically designing a durable SHS. In the first part of this work, we discuss two new design parameters that can be used to develop mechanically durable SHSs via the spray coating of different binders and fillers. These parameters aid in the rational selection of material components and allow one to predict the capillary resistance to wetting of any SHS from a simple topographical analysis. We show that not all combinations of sprayable components generate SHSs, and mechanically durable components do not necessarily generate mechanically durable SHSs. Moreover, even the most durable SHSs can eventually become damaged. In the second part, utilizing our new parameters, we design and fabricate physically and chemically self-healing SHSs. The most promising surface is fabricated from a fluorinated polyurethane elastomer (FPU) and the extremely hydrophobic small molecule 1H,1H,2H,2H-heptadecafluorodecyl polyhedral oligomeric silsesquioxane (F-POSS). A sprayed FPU/F-POSS surface can recover its superhydrophobicity even after being abraded, scratched, burned, plasma-cleaned, flattened, sonicated, and chemically attacked