Application of environmental scanning electron microscopy in the development of detergents and personal products
Environmental scanning electron microscopy enables the observation of samples in their natural state with no preparation. Unilever Research employs this technology in the research and development of detergents and personal products with much success. The results presented are from various studies which demonstrate the versatility and utility of the technique. Vacuum sensitive samples such as microcapsules were successfully characterized, the efficacy of dental products was shown by monitoring an enamel surface before and after treatment, and the performance of an adhesive was assessed by dynamic experimentation. © 1993 Wiley‐Liss, Inc.
Advancements in Spectroscopic and Microscopic Techniques for Investigating the Adsorption of Conditioning Polymers onto Human Hair
Adsorption of the polyquaternium-6 (Merquat®-100) conditioning polymer onto bleached human hair has been investigated using environmental scanning electron microscopy (ESEM), X-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). ESEM is not limited to a high-vacuum environment, and therefore hair morphology could be studied under ambient and hydrated conditions. XPS gave elemental analysis on the surface of the hair, in addition to information on the chemical environment of the surface atoms. SIMS can produce high-resolution ion distribution images on the hair's surface. Both XPS and SIMS detected carbon, nitrogen, oxygen, and sulfur on the surface of the untreated bleached hair, all of which were attributed to the biological matrix. Silicon was also detected and its presence was attributed to either a previous silicone cosmetic application or to surface contamination. Due to the similar elemental composition of hair and Merquat-100, treatment of the hair with a phosphorus-labeled polyquaternium-6 cationic conditioning polymer was also investigated. XPS, with sensitivity of 1000 parts per million (ppm), could not detect phosphorus present from any adsorbed polymer, but SIMS, with 1-10 ppm sensitivity, allowed high-resolution images to be obtained that illustrated the adsorption of polymer onto the hair's surface.
Design and construction of an environmental SEM (part 4)
A new detection configuration using the gaseous detector device in the environmental scanning electron microscope (ESEM) is demonstrated. First, the pressure-limiting aperture (PLA1) is used simultaneously as a biased electrode to collect the ionization current produced in the gaseous environment of the microscope. Second, a wire electrode is placed above the pressure-limiting aperture, and it is shown that enough signal from the specimen escapes through the aperture to produce satisfactory images. These detection configurations allow the use of high specimen chamber pressures.