Crystallization of calcium sulfate on polymeric surfaces

Surface crystallization of calcium sulfate dihydrate (gypsum) on a series of polymeric surfaces was studied using a quartz microbalance system. Polyelectrolyte multilayer films (positively and negatively charged surfaces) were formed on the quartz crystal microbalance (QCM) sensors utilizing a layer-by-layer spin-assembly method. The kinetics of gypsum surface crystallization was quantified in terms of the evolution of gypsum mineral scale on the different surfaces. For comparison mineral scaling was also evaluated on silica and polyamide surfaces. For surfaces of the same charge polarity (+/-), the mass density of gypsum scale was lower (PSS