Robert Gregory Bartolo

The influence of hard water (calcium) and surfactants on irritant contact dermatitis

Although the induction of irritant contact dermatitis has been extensively studied for surfactants, the role of the environmental factor water hardness (i.e., calcium content) on the induction process has not received attention. Our objective was 10 investigate differences in surfactant‐induced irritant skin reactions from cumulative exposure to 3 different personal cleansing agents and determine whether the irritation potential can be affected by the hardness of the water. 2 commonly used exaggerated washing procedures were variously employed lo evaluate representative sodium‐soap, triethanolamine‐soap, or synthetic detergent cleansers under conditions where the water hardness varied from 0‐grain to 11‐grain (gr). Subjects were clinically evaluated for skin dryness, skin redness, and instrumentally for hydration. Soap binding to skin was quantified using Fourier transform infrared reflectance spectroscopy. Using the more mild wash procedure, skin sites treated under conditions of hard. 11 gr water, were significantly drier, had more erythema, and were less hydrated than corresponding sites treated with deionized 0 gr water. All 3 surfactant cleansers behaved similarly. We also found the hardness of the rinse water to be the more significant factor, versus that of the wash water. Effect of water hardness on soap binding to skin revealed a similar outcome. Under a more exaggerated wash condition the relationship between water hardness and irritation broke down.

Characterization of Lyotropic Polysaccharide Liquid Crystal Blends

Abstract Liquid crystalline polymers (LCPs) have been the focus of much interest over the past decade or so, due principally to the fact that they exhibit a structured mesophase under certain thermal or solvent conditions. Such supramolecular organization not only provides useful insight into the conformational behavior of these materials but also makes this family of polymers particularly attractive for specialized applications. Derivatives of crystalline cellulose have received considerable attention in this vein, since many commercial products employ these and other polysaccharides, and one of the most studied cellulosic LCPs is hydroxypropylcellulose (HPC). While past efforts have focused on the phase diagram of this polymer in various solvents and at elevated temperatures (HPC possesses both lyotropic and thermotropic properties), the objective of the present work is to characterize blends of HPC with another semiflexible polysaccharide, xanthan gum (XG), which also possesses lyotropic properties. Here, we have employed deuterium nuclear magnetic resonance (2H NMR) and freeze-fracture transmission electron microscopy (FF/TEM) to characterize the mesophases of these homopolymers and their blends in both aqueous and organic solvents. We provide evidence that HPC and XG, when blended together in an aqueous medium, are synergistic in mesophase formation over a finite composition range, appearing more anisotropic than either component individually (at identical solution concentration). However, addition of XG to HPC in an organic solvent results in a two-phase isotropic/anisotropic system.

Enhanced anisotropic ordering and phase separation in lyotropic polysaccharide blends

Abstract 2 H n.m.r. spectroscopy is employed to characterize the mesomorphic behaviour of hydroxypropyl cellulose (HPC) in D 2 O. This analysis is further extended to ternary solutions containing HPC and xanthan gum (XG). A compositional range over which addition of XG to HPC enhances single-phase anisotropic ordering is reported. Convoluted spectra representative of HPC-rich and XG-rich components are observed at some blend and solution concentrations, suggesting that phase separation occurs between these two lyotropic polysaccharides.