Organic mixed ionic-electronic conductors, particularly poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), are fundamental to iontronics, yet achieving efficient ionic-electronic coupling remains challenging due to inhomogeneous phase distribution between the electronically conducting PEDOT and ionically conducting PSS domains. Here, we employ A-type nanogrids (AGs) as molecular additives to systematically tailor PEDOT:PSS nanostructure. AG-H (hydrogen substituent) and AG-PhOC8 (octyloxybenzyl substituent) promote uniform phase distribution, enhancing PEDOT/PSS contact and improving ionic-electronic coupling. In contrast, bulky phenyl-substituted AG-Ph exacerbates phase separation, degrading performance. We attribute this to the ability of wedge-shaped AG-H and the flexible octyloxy chain of AG-PhOC8 to penetrate and fragment PEDOT aggregates, while AG-Ph acts as an interfacial spacer. In electrochemical actuation, AG-H and AG-PhOC8-modified PEDOT:PSS electrodes achieve outstanding performance, with displacements >20 mm and bending angles of ≈100° under high-frequency (1.0 Hz), low-voltage (3.0 V) excitation, substantially exceeding pristine PEDOT:PSS and many reported electrodes. This work establishes a molecular-level strategy for tailoring PEDOT:PSS phase structure, enabling advanced flexible actuators for soft robotics.
Li et al. (Sun,) studied this question.