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Spread films of a poly(ethylene oxide)-polystyrene diblock copolymer were studied at the h a t e r and heptanewater interfaces by using the Wilhelmy plate technique and surface quasi-elastic light scattering (SLS) from capillary waves. At the air-water interface, the dynamic f i l m viscoelastic parameters, Le., surface pressure, surface dilational elasticity and viscosity, and transverse viscosity, were deduced from the SLS measurements. The static surface tension and dilational elasticity were compared to their dynamic counterparts from SLS. At the heptanewater interface, the dynamic surface pressure and transverse viscosity were evaluated, and the latter was found to be zero for the whole surface concentration range. Some speculations about possible chain conformations of the copolymer at the two interfaces are offered.

The solubility of Sn(IV) in cementitious systems is directly related to the presence of dissolved Ca. In the presence of typical Ca concentrations, solid Ca[Sn(OH)A constant of 10

The solubility of Ni, Sn, Pb, Eu, and Sr was investigated at 22°C and 50°C in simulated cement porewaters corresponding to fresh cement (‘FPW’, pH 13.2) and cement leached of soluble alkalis, whose porewater chemistry is dominated by equilibrium with portlandite (‘APW’, pH 12.5). Solubility limits were approached from undersaturation, using Ni(OH)2(c), SnO2(c) (cassiterite), PbO(red), and Eu(OH)3(c) as solids. For Sr, no solubility experiments were carried out since the cement contains enough Sr to reach equilibrium with strontianite and celestite. Solubilities generally increase with increasing pH and temperature. The measured solubility of Pb ranges from about 4× 10−3 to 1×1O−2M and is within thermodynamically predicted values. The measured solubility of Ni is <O.5-1.3×10−7M in APW and about 3-4×10−7M in FPW, which is lower than predicted by most thermodynamic data. The measured solubility of Eu ranges from <6.6×10−10M in APW to 1.8-2.7×10−9M in FPW, which agrees well with thermodynamic calculations. The solubility of cassiterite is low, with dissolved Sn concentrations ranging from 3.5× 10−8M in APW to 3.3× 10−6M in FPW. Thermodynamic calculations predict much higher solubilities, presumably for less crystalline phases. However, oversaturation measurements in APW reproduced the solubility limits obtained by undersaturation within a factor of two. To our knowledge, no relevant thermodynamic data are available.