Tuning Crystallinity in PSS‐g‐PEO Co‐Polyelectrolyte Brushes for Electrical Applications

ABSTRACT The regulation of the level of crystallinity and mixed charge transport in polystyrene sulfonate grafted by polyethylene oxide (PSS‐g‐PEO) co‐polyelectrolyte brushes is examined. These systems are commonly regarded as pH‐insensitive due to the low pKa of sulfonic acid groups. In the present study, however, it was shown that PSS‐g‐PEO systems display significant levels of stimulus response based on the regulation of the extensive interchain hydrogen bonding network. Using a potassium hydroxide (KOH) titration method, the level of crystallinity can be regulated from 37% at pH 2 to a minimum of 30% at pH 10, as characterized by X‐ray diffraction (XRD). This decrease in crystallinity was accompanied by a significant increase in electrical conductivity up to 1.17 × 10 −4 S cm −1 , based on reduced tortuosity of ion hopping pathways and increased segmental mobility in the amorphous phase. These results were characterized by temperature‐dependent methods, confirming the Arrhenius nature of ion transport, with activation energy profiles closely related to hydration state and electrostatic environment of the brushes. These results offer a significant framework for the development of intelligent actuators and high‐performance organic electrochemical transistors (OECTs), confirming the potential of hydrogen bonding engineering in strong polyelectrolyte systems.