Increase in Interfacial Adhesion and Electrochemical Charge Storage Capacity of Polypyrrole on Au Electrodes Using Polyethyleneimine

Abstract

High-performance devices based on conducting polymers (CPs) require the fabrication of a thick CP-coated electrode with high stability. Herein, we propose a method for enhancing the interfacial adhesion strength between a gold electrode and an electropolymerized polypyrrole (pPy) layer by introducing a polyethyleneimine (PEI) layer. Although this insulating layer hinders the initial growth of the pPy layer on the Au surface, it improves the adhesion by up to 250%. Therefore, a thick layer of pPy can be fabricated without delamination during drying. X-ray photoelectron spectroscopy shows that the PEI layer interacts with the Au surface via polar/ionic groups and van der Waals interactions. Scanning electron microscopy reveals that the cohesion of the pPy layer is stronger than the interfacial adhesion between the PEI layer and the pPy layer. Importantly, the electroactivities of pPy and its dopant are unaffected by the PEI layer, and the electrochemical storage capacity of the pPy layers on the PEI-coated Au electrodes increases with thickness, reaching ~530 mC/cm2. Negative potential sweep is detrimental to pPy layer adhesion: pPy layers on a bare Au electrode peel off instantly as the potential is swept from 0.2 to −0.7 V, and most of the charge stored in the layer becomes inaccessible. In contrast, pPy layers deposited on PEI coated Au electrode are mechanically stable and majority of the charge can be accessed, demonstrating that this method is also effective for enhancing electrochemical stability. Our simple approach can find utility in various applications involving CP-coated electrodes, where thickness-dependent performance must be improved without loss of stability.

Soft-robotic ciliated epidermis for reconfigurable coordinated fluid manipulation

“…S11) due to the delamination and degradation of the PPy layer ( 27 ). Potential underdevelopment solutions in the literature to this challenging unsolved problem include enhancing the polymer/electrode adhesion by surface roughening ( 24 ) or introducing an adhesion layer ( 45 ), reducing the actuation potential range ( 46 ), synthesizing PPy composites ( 47 , 48 ), and engineering the micro/nanostructures of the PPy ( 49 ). Other bending actuators built upon inorganic materials, such as carbon nanotube or graphene ( 50 , 51 ), could also be explored to create durable soft-robotic ciliated epidermises.…”

Carbon-Based Polymer Nanocomposite for High-Performance Energy Storage Applications

“…To build effective CP electrodes/probe, it is usually advisable to store a compact CP film at the electrode because its activity is hugely reliant upon this layer's depth; for example, the areal ED/PD (Wh/cm 2 , W/cm 2 ) or activating drive of a CP probe is equivalent to its thickness [95]. It has been noticed that the initiation of MWCNTs within the polymeric patterns increases the specific exterior area and recovers the electrical performance and mechanical characteristics [96].…”

Immobilized cellulose nanospheres in lateral flow immunoassay enable rapid nucleocapsid antigen-based diagnosis of SARS-CoV-2 from salivary samples

“…The cationic materials were used as anchor layers to improve the extent of adsorption on the surfaces, whereas anionic nanoparticles were used as blocking material. The PEI, as a cationic polymer, is commonly used as coating material, adhesive, surface modifier, and anchoring layer for different polymers and cell cultures [37][38][39][40] . The material treatments were done by injecting 0.5 wt% aqueous solutions of each material onto the model films in situ in the QCM unit before adsorption of the proteins.…”