Characterizing the Adsorption of Poly(vinyl alcohol) on Colloidal Silica with Aggregation-Induced Emission Fluorophore.

The adsorption of polymer on colloidal particle has significant influence on colloid structure and dynamics. Here we introduce a new method to monitor the adsorption in situ, based on the different emission behavior of aggregation-induced emission (AIE) luminogen in different micro environments. Poly(vinyl alcohol) (PVA) and colloidal silica (CS) were used as a model system. It was found that AIE molecules exhibited extremely low fluorescence intensity in water and PVA solution, while their emission efficiency was enhanced when adsorbed on CS, and became significantly boosted when PVA was adsorbed on CS at the same time. The fluorescence intensity increases with the amount of added PVA and reaches a saturation point, which is earlier than that obtained by the well-established solvent relaxation NMR method, due to their different sensitivities for adsorption segments in specific conformation. This new method is advantageous in quick response, where the measurement can be finished within 2 min, while others usually take hours. Therefore, it is expected that this new method may be used to monitor the dynamical adsorption process of polymer on colloidal particles.