Surface modification of polyaniline nanorods with thiol-terminated poly(ethylene oxide)

Electrochemically grown polyaniline (PAni) thin films have been shown to react efficiently with thiols, which can dramatically change the surface properties of the material without significantly impacting bulk conductivity. Such films, however, are difficult to process and are unsuitable for many applications. Here, we demonstrate the grafting of thiol-terminated poly(ethylene oxide) (PEG- SH) of various molecular weights onto PAni nanorods. The resulting materials are characterized by spectroscopic, microscopic, and thermal analytical methods to demonstrate the covalent attachment of the PEG polymers to the nanorods. The derivatized nanorods are water dispersible and maintain their original morphology and electroactivity. The number of thiols bound to the nanoparticles under a given set of conditions decreases as the size increases, but the total mass of PEG increases with increasing size. The reaction proceeds at room temperature, but is much faster at higher temperature and greater PEG density is observed

Effects of Side-Chain Length and Functionality on Polar Poly(dioxythiophene)s for Saline-Based Organic Electrochemical Transistors.

Understanding the impact of side chains on the aqueous redox properties of conjugated polymers is crucial to unlocking their potential in bioelectrochemical devices, such as organic electrochemical transistors (OECTs). Here, we report a series of polar propylenedioxythiophene-based copolymers functionalized with glyme side chains of varying lengths as well as an analogue with short hydroxyl side chains. We show that long polar side chains are not required for achieving high volumetric capacitance (C*), as short hydroxy substituents can afford facile doping and high C* in saline-based electrolytes. Furthermore, we demonstrate that varying the length of the polar glyme chains leads to subtle changes in material properties. Increasing the length of glyme side chain is generally associated with an enhancement in OECT performance, doping kinetics, and stability, with the polymer bearing the longest side chains exhibiting the highest performance ([μC*]OECT = 200 ± 8 F cm-1 V-1 s-1). The origin of this performance enhancement is investigated in different device configurations using in situ techniques (e.g., time-resolved spectroelectrochemistry and chronoamperometry). These studies suggest that the performance improvement is not due to significant changes in C* but rather due to variations in the inferred mobility. Through a thorough comparison of two different architectures, we demonstrate that device geometry can obfuscate the benchmarking of OECT active channel materials, likely due to contact resistance effects. By complementing all electrochemical and spectroscopic experiments with in situ measurements performed within a planar OECT device configuration, this work seeks to unambiguously assign material design principles to fine-tune the properties of poly(dioxythiophene)s relevant for application in OECTs

Surface modification of polyaniline nanorods with thiol-terminated poly(ethylene oxide)

Electrochemically grown polyaniline (PAni) thin films have been shown to react efficiently with thiols, which can dramatically change the surface properties of the material without significantly impacting bulk conductivity. Such films, however, are difficult to process and are unsuitable for many applications. Here, we demonstrate the grafting of thiol-terminated poly(ethylene oxide) (PEG-SH) of various molecular weights onto PAni nanorods. The resulting materials are characterized by spectroscopic, microscopic, and thermal analytical methods to demonstrate the covalent attachment of the PEG polymers to the nanorods. The derivatized nanorods are water dispersible and maintain their original morphology and electroactivity. The number of thiols bound to the nanoparticles under a given set of conditions decreases as the size increases, but the total mass of PEG increases with increasing size. The reaction proceeds at room temperature, but is much faster at higher temperature and greater PEG density is observed