The conformational behavior of polymers in clay-polymer nanocomposites (CPN) is not fully understood because of the many factors involved. The purpose of the present study was to investigate the conformational behavior of a polymer at the micro- and meso-scales in order to predict the behavior of tunable CPN. The study used a pH-responsive polymer, polyacrylamide, which has time-dependent hydrolysis response properties, to examine micro-scale conformational behavior of the polymer adsorbed on representative clay-mineral surfaces, SiO2 and Al2O3. A nanocomposite and a microcomposite were used to link meso-scale CPN behavior to micro-scale polymer conformation. The conformational behavior was characterized using in situ, real-time spectroscopic ellipsometry. The contracted coil conformation of polyacrylamide was observed at pH = 3, while extended conformation was observed at pH = 11.5 on both SiO2 and Al2O3 surfaces. At pH = 11.5, the polymer conformation changed from expanded coil to extended conformation over time. The polymer conformation changed more rapidly with the Al2O3 surface due to mineral dissolution at pH = 3 and 11.5. Swelling tests were conducted as functions of pH and time to link the micro-scale phenomena to meso-scale CPN behavior. The results indicated that the swelling potential of CPN corresponded to the conformation of adsorbed polyacrylamide, which varied with pH and time. The swelling potential of CPN was maximized at pH = 11.5 and decreased with decreasing pH, corresponding to the observed micro-scale conformational behavior.

An array of nano-scale protrusions, called the nipple array, is found on the body surface of various invertebrates, and this structure is believed to decrease light reflectance and water wettability on the surface in the terrestrial environment. However, its potential functions have not been well studied in aquatic environments. Clavelina spp. are colonial ascidians that have the nipple array on their integumentary matrix (i.e. tunic). We examined the physical properties on the surface of the tunic of C. cyclus and C. obesa, such as hardness, wettability and refractive indices, to evaluate the functional importance of this structure. The tunic cuticle of both species was covered with the nipple array, and the cuticle of C. cyclus was bent into folds forming parallel plications. The Clavelina tunic was very soft and had high bubble- and oil-repellency. The refractive-index deviation between the tunic and seawater was 0.07–0.095 for 589-nm light (D-line). Rigorous coupled wave analysis (RCWA) showed that the nipple array slightly reduced reflectance on the surface and the parallel plications reduced the reflectance still more. The nanoimprinted plates imitating the parallel plications have higher bubble repellency and lower reflectance than the flat plates. These findings support the functional importance of the plications as well as the nipple array.

In this paper, a non-destructive method is proposed for measuring the density of a verythin lubricant layer (weight and spatial) on an industrial surface. We consideredspectroscopic ellipsometry measurements on rough tinplated steel substrates protected by alubrication layer. The thickness of the coating was less than the roughness parametercharacterizing the metallic surface. As the optical properties of the substrates could notbe modelled in a conventional way due to the roughness and the complex structure of themetal, the variations of one of the ellipsometric angle (Δ) were evaluated as a functionof the lubricant film surface density. After identification of the potential outliersusing a multivariate analysis technique based on the Mahalanobis distance, we interpretedthe data using the Drude’s approximation for thin dielectric films. The values of Δlinearly decrease with the lubricant surface density, allowing us to evaluate locally thelubricant surface density and its point-to-point variations.