We studied the adsorption of polyethylene glycol （PEG） and amphiphilic polyoxyethylene-polyoxypropylene-polyoxyethylene （PEO-PPO-PEO） triblock copolymers （Pluronic surfactants） on a model metal substrate（gold）and assessed their suppressive effect on copper electrodeposition. The adsorption was characterized using a quartz crystal microbalance with dissipation monitoring （QCM-D） technique and ellipsometry. The electrodeposition-suppressive effect was assessed using linear sweep voltammetry （LSV）. Results showed that the adsorption rate of these additives on the metal substrate contributed to the electrodeposition-suppressive effect to a greater extent than the adsorption mass （or the adsorption density）, as inferred for previously reported cationic surfactant systems. The addition of HCl into an H2SO4 aqueous solution increased the adsorption mass of hydrated PEO, leading to increased suppressive effects on copper electrodeposition. In contrast, addition of HCl decreased suppressive effects in the Pluronic surfactant systems, although their adsorption occurred in a manner similar to that for cationic surfactant systems for shorter PEO analogs and in a manner similar to that for the PEG systems for a longer PEO analog. These results suggest that the electrodeposition-suppressive effect is influenced mainly by the adsorption rate, but hydration of the adsorption layer and the adsorption ability also contribute to the suppressive effect.
Rapid determination of metal ion concentrations in plating solutions of eight kinds was studied with compact low-power XRF instruments equipped with a liquid flow cell. Stretched 12 micrometer polypropylene film was installed for this liquid cell. A small aliquot of the plating solution and the internal solution were weighed and put into a 5 ml plastic vial and were mixed well. The mixed solution of 2 ml in the 5 ml vial was then supplied to the liquid cell by a peristaltic pump. All XRF spectra were accumulated by real-time measurement of 30 s. The X-ray tube power was less than 2 W. The averages and differences of the metal ion concentrations of the commercial plating solutions of the eight kinds of plating solutions for nickel, copper, zinc, platinum, gold, rhodium, silver, and tin were determined respectively as 19.6＋/－0.1, 44.2＋/－0.2, 128＋/－0.1, 12.1＋/－0.2, 6.1＋/－0.04, 3.1＋/－0.02, 82.2＋/－0.4, and 16.8＋/－0.3 in g/L. The detection limits of metal ion in the five plating solutions of nickel, copper, zinc, rhodium, and silver were less than 0.3 g/L. For the platinum, the gold, and the tin plating solutions, the detection limit was obtained as 0.7－1.1 g/L by the X－ray tube background or by scattering effects. Results show that the low－power XRF spectrometer equipped with the liquid cell is a useful instrument for rapid and accurate analysis of the plating metal ion concentrations of many plating solutions.
Transition from solvent-based paints to water-based paints in the painting industry has progressed to reduce the use of volatile organic compounds, which are harmful to humans and the environment. However, water-based paints have a problem with paint workability because of sagging. Cellulose nanofiber (CNF), which has attracted attention as a novel naturally available material, exhibits high mechanical strength, thickening effects, and a low coefficient of thermal expansion. To resolve difficulties related to water-based paints, we examined paint and coating films characteristics after adding CNF. Results demonstrated that adding 0.2 mass% CNF can prevent sagging. Paint separation attributable to pigment sedimentation was prevented for 10 days. By adding 0.5 mass% CNF, the tensile strength of a coating film became more than double that of a non-CNF coating film. Testing using ballotini method indicated that CNF addition decreased the coating film surface dryness. Measurements using AC impedance indicated decreased coating film water resistance.