In Situ Nanoscale Characterization of Water Penetration through Plasma Polymerized Coatings.

The search continues for means of making quick determinations of the efficacy of a coating for protecting a metal surface against corrosion. One means of reducing the time scale needed to differentiate the performance of different coatings is to draw from nanoscale measurements inferences about macroscopic behavior. Here we connect observations of the penetration of water into plasma polymerized (PP) protective coatings and the character of the interface between the coating and an oxide-coated aluminum substrate or model oxide-coated silicon substrate to the macroscopically observable corrosion for those systems.

Insight on Structure of Water and Ice Next to Graphene Using Surface-Sensitive Spectroscopy.

The water/graphene interface has received considerable attention in the past decade due to its relevance in various potential applications including energy storage, sensing, desalination, and catalysis. Most of our knowledge about the interfacial water structure next to graphene stems from simulations, which use experimentally measured water contact angles (WCAs) on graphene (or graphite) to estimate the water-graphene interaction strength. However, the existence of a wide spectrum of reported WCAs on supported graphene and graphitic surfaces makes it difficult to interpret the water-graphene interactions.

Hard water softening effect of a baby cleanser.

Background: Hard water is associated with atopic dermatitis (eczema). We wanted to determine if a baby cleanser and its individual components altered free ionized calcium (Ca) in a simulated hard water baby bath. For these studies, an in vitro determination of free Ca in a simulated hard water baby bath, and an in vivo exploratory study of free Ca absorption into skin from hard water were performed.

Effect of Surface Energy on Freezing Temperature of Water.

Previous studies have found that superhydrophobic surfaces are effective in delaying freezing of water droplets. However, the freezing process of water droplets on superhydrophobic surfaces depends on factors such as droplet size, surface area, roughness, and cooling rate. The role of surface energy, independent of any other parameters, in delaying freezing of water is not understood.

Interfacial Water at Polyurethane-Sapphire Interface.

Infrared-visible sum frequency generation spectroscopy (SFG) was used to directly probe water between polyurethane (PU) and sapphire substrates after exposing samples to liquid water and water vapor. For liquid water, the observation of SFG peaks associated with H2O bands (3000-3400 cm(-1)) and D2O bands (2300-2600 cm(-1)) indicated water molecules diffused to the buried interface and existed in the form of a hydrogen-bonded water network. The water layer disrupted interactions between polyurethane and sapphire.

The effect of a solid surface on the segregation and melting of salt hydrates.

Considering the importance of salt and water on earth, the crystallization of salt hydrates next to solid surfaces has important implications in physical and biological sciences. Heterogeneous nucleation is driven by surface interactions, but our understanding of hydrate formation near surfaces is limited. Here, we have studied the hydrate formation of three commonly prevalent salts, MgCl2, CaCl2, and NaCl, next to a sapphire substrate using surface sensitive infrared-visible sum frequency generation (SFG) spectroscopy.

Freezing and melting of salt hydrates next to solid surfaces probed by infrared-visible sum frequency generation spectroscopy.

Understanding the freezing of salt solutions near solid surfaces is important in many scientific fields. Here we use sum frequency generation (SFG) spectroscopy to study the freezing of a NaCl solution next to a sapphire substrate. During cooling we observe two transitions.

Freezing of water next to solid surfaces probed by infrared-visible sum frequency generation spectroscopy.

Ice formation next to solid surfaces is important in many biological, materials, and geological phenomena and may be a factor in how they impact various technologies. We have used sum frequency generation (SFG) spectroscopy to study the structure of ice as well as the freezing and melting transition temperatures of water in contact with sapphire substrates. We have observed that the structure of ice and water are a function of pH and the surface charge of the sapphire substrate.

Control of surface chemistry, substrate stiffness, and cell function in a novel terpolymer methacrylate library.

A focused library of methacrylate terpolymers was synthesized to explore the effects of varying surface chemistry and adhesive peptide ligands on cell function. The chemical diversity of methacrylate monomers enabled construction of a library of polymers in which one can systematically vary the chemical composition to achieve a wide range of contact angle, Young's modulus, and T(g) values. Furthermore, the materials were designed to allow surface immobilization of bioactive peptides.

Simple, rapid, and highly sensitive detection of diphosgene and triphosgene by spectrophotometric methods.

Methods for the detection and estimation of diphosgene and triphosgene are described. These compounds are widely used phosgene precursors which produce an intensely colored purple pentamethine oxonol dye when reacted with 1,3-dimethylbarbituric acid (DBA) and pyridine (or a pyridine derivative). Two quantitative methods are described, based on either UV absorbance or fluorescence of the oxonol dye.