Investigation Of The Adsorption Characteristics Of Polyelectrolyte And Room Temperature Ionic Liquids By Piezoelectric Sensors

In this dissertation, the adsorption characteristics of a polyelectrolyte and ionic liquids were investigated by an electrode-separated piezoelectric sensorESPS) and a langasite crystal microbalance (LCM). The main results were listedbelow.1) In the construction of the ESPS, quartz surface is in a direct contact with the liquid phase, which offers the convenience to monitor the adsorption of cationic polyelectrolyte on a negatively charged surface by piezoelectric sensor. The adsorbed amounts of polydiallyldimethyl ammonium chloride (PDMDAAC) on quartz surface were monitored in real time by the ESPS. The adsorption isotherms are in Langmuir type. The adsorption rate constants were determined. With PDMDAAC adsorbed on quartz surface used as the positively charged model surface, the adsorption processes of a anionic dye, Reactive Red K-2BP, and SiO₂ nanoparticle on cationic polyelectrolyte were investigated. The influence of pH and ionic strength on the adsorption isotherms and rate constants were discussed. In combined with spectrometric and zeta potential methods, the reversibility of the adsorptions was tested.2) Langasite (La₃Ga₅SiO₁₄) crystal is one of the perspective crystalline materials for various applications in acoustoelectron and piezoelectric devices. In this work, the frequency responses of resonators made from Y-cut langasite crystal in a liquid phase were investigated. It was shown that the oscillating frequency of the langasite resonator decreased with increasing the surface mass loading, viscosity (η) and density (ρ) of the liquid phase. The correlation of the frequency...