Polysiloxanes with Quaternary Ammonium and Polyether Groups for Silyl-Terminated Polypropylene Oxide Waterborne Emulsions

摘要

In this paper, polysiloxanes with pendant quaternary ammonium and polyether segments (EQAPS, nonionic-cationic silicone surfactant) were synthesized through hydrosilylation of poly(dimethylhydro) siloxane with allyl poly(ethylene glycol) acetic ester (M-n = 540) and allyl glycidyl ether, followed by a ring-opening reaction of epoxide groups with diethyl amine and quaternization with benzyl chloride. The chemical structures of EQAPS and intermediate products were characterized by H-1-NMR and FT-IR spectra. The surface activity and thermal properties of EQAPS were studied with surface tension measurement and differential scanning calorimetry analysis, respectively. The results showed that the EQAPS had a much smaller critical micelle concentration value (118 mg/L) and lower glass-transition temperature (T-g: -57 degrees C). The silyl-terminated polypropylene oxide waterborne emulsions, which were substantially free from organic solvent, were prepared via a phase-inversion emulsification technique using EQAPS as single emulsifier and/or poly(ethylene glycol) ((M) over bar (n) = 400) as cosolvent. The electrical properties of the system indicated that the phase inversion was completely accomplished. The viscosity of the emulsions with different solid contents was measured, and the results showed that the most suitable solid content was about 50 wt%. The emulsions with smaller particle size (12 mu m) had better storage stability (48 days at 50 degrees C) and freeze-thaw stability.