Probing effect of counterions on electric field stimuli responsive behaviours of smart organoboron-based polyelectrolytes

Abstract

This is the first study to be introduced to the electrorheology (ER) literature focusing on organoboron-based polyelectrolyte colloidal systems namely: polymeric lithium tartaric acid borate (Poly-LiTB) and polymeric sodium tartaric acid borate (Poly-NaTB). Syntheses of functional polyelectrolytes were monitored via 1H NMR, ATR-FTIR and SEM-EDX analyses. Electrical conductivity measurements indicated that Poly-LiTB and Poly-NaTB were in semi-conductive region indicating potential smart ER behaviour. A higher polarizability was detected for 20 wt% Poly-LiTB dispersions in silicone oil (SO) by dielectric measurements. As expected, improved ER performances were obtained for Poly-LiTB/SO colloidal dispersion (τy = 265 Pa, EReff = 87, G′ = 80 kPa at 10 Hz, τc = 98 Pa, recovery% = 68) compared to Poly-NaTB/SO colloidal dispersion (τy = 195 Pa, EReff = 38, G′ = 42 kPa at 10 Hz, τc = 42 Pa, recovery% = 67). To sum up, it was determined that the best ER activity was detected by the organoboron−based polyelectrolyte containing Li+ counterion with smaller ionic radius and higher ionic mobility when their physicochemical properties are taken into account.