Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE The present study showed that the hydrogen bonding network of PSS-g-PEO co-polyelectrolyte brushes can be controlled to tune their bulk crystallinity. The pH-dependent film crystallinity decreases from 2 to 10, which greatly increases the electrical conductivity to 1.17 × 10−4 S.cm−1.


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.