Simultaneous Vapor-Phase Polymerization of PEDOT and a Siloxane into Organic/Inorganic Hybrid Thin Films

Highly porous, soft, and flexible vapor-phase polymerized polypyrrole-styrene-ethylene-butylene-styrene hybrid scaffold as ammonia and strain sensor

Herein, in situ vapor-phase polymerization (VPP) of pyrrole on an oxidant-impregnated styrene–ethylene–butylene–styrene (SEBS) matrix comprising a three-dimensional sugar particle assembly was used to produce a soft and porous polypyrrole (PPy)–SEBS hybrid scaffold. Characterization of the PPy–SEBS hybrid scaffold using field-effect scanning electron microscopy, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and micro-computerized tomography confirmed the successful uniform and homogenous polymerization of PPy onto the SEBS matrix with a porous morphology. The performance of the hybrid scaffold of different pore sizes as an ammonia sensor under different temperature conditions was evaluated in terms of resistance change. The results showed that the PPy–SEBS scaffolds of larger pore size had higher resistance changes under lower temperature conditions when ammonia (NH₃) gas was introduced compared to those observed for smaller pore sizes under higher temperature conditions. These scaffolds showed excellent repeatability and reversibility in detecting NH₃ gas with fast response and recovery times of 30 s and 10–15 min, respectively. Moreover, the larger pore size scaffolds polymerized for a longer time possessed a remarkable ability to be applied as strain sensors. These kinds of novel, soft, and porous conductive polymer composite materials produced by VPP will have huge practical applications in monitoring other toxic and non-toxic gases.

Fabrication of a hybrid scaffold from an oxidant-impregnated styrene–ethylene–butylene–styrene (SEBS) matrix comprising a three-dimensional sugar particle assembly by vapor phase polymerization (VPP).

Precise control of nanoscale spacing between electrodes using different natured self-assembled monolayers

Herein, we introduce an interdigitated horizontal electrode (IHE) structure with a metal-based electron-collecting (or -injecting) electrode and a hole-collecting (or -injecting) electrode composed of a conductive polymeric material that has a nanoscale distance and is horizontally separated. In the IHE, a metal electrode is fabricated on a silicon-oxide substrate, and a self-assembled monolayer (SAM) is selectively bonded to the metal and the oxide to form a conductive polymer electrode by dip coating. Each of the SAM materials is composed of a head part bonded to the substrate surface and a tail part that is hydrophilic or hydrophobic. This inherent property makes the metal electrode hydrophobic and the oxide substrate hydrophilic. Ag is used as a metal electrode material and is combined with alkanethiol SAMs. The alkylsilane SAMs are combined with the silicon oxide substrate to make them hydrophilic, using poly (3, 4-ethylenedioxythiophene)-poly (PEDOT: PSS) as the conductive polymer material. In this study, we have found that there is a difference in the spacing between the two electrodes that depends on the combination of SAM materials. Each interval was spaced from a minimum of 140 nm to a maximum of 385 nm.

Fabrication of an electroconductive, flexible, and soft poly(3,4-ethylenedioxythiophene)-thermoplastic polyurethane hybrid scaffold by in situ vapor phase polymerization

The inherent insolubility and brittleness of poly(3,4-ethylenedioxythiophene) (PEDOT) reduce its processability and practical applicability. Herein, we use in situ vapor phase polymerization (VPP) of 3,4-ethylenedioxythiophene (EDOT) on an oxidant-impregnated thermoplastic polyurethane (TPU) matrix comprising a three-dimensional silica particle assembly to produce a soft, flexible, and conductive TPU-PEDOT hybrid scaffold. The selective removal of silica yielded a highly porous (∼95%) skeletal structure, with the effective penetration, diffusion, and polymerization of EDOT resulting in uniform PEDOT formation both on the surface and the inner side of the TPU matrix. The mechanical and electrical properties of the obtained scaffold were investigated by bending, compression testing, and stress-strain and electrical measurements. The electrical resistance of the scaffold equaled 17 kΩ and did not change after ∼500-fold bending, whereas the observed elastic modulus was much lower (300 kPa) than that of TPU (3.3 MPa). In vitro biocompatibility was investigated by MC3T3-E1 cell culturing with cell viability evaluated using the WST assay and cell morphology examined by confocal microscopy. Thus, the soft and flexible TPU-PEDOT hybrid scaffold produced by VPP might be practically useful, implying that this preliminary investigation needs to be extended to study the behavior of muscle and nerve cells under electrical stimulation.

Vapor phase polymerization deposition of conducting polymer/graphene nanocomposites as high performance electrode materials

In this paper, we report chemical vapor phase polymerization (VPP) deposition of novel poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene nanocomposites as solid tantalum electrolyte capacitor cathode films. The PEDOT/graphene films were successfully prepared on porous tantalum pentoxide surface as cathode films through the VPP procedure. The results indicated that the high conductivity nature of PEDOT/graphene leads to the decrease of cathode films resistance and contact resistance between PEDOT/graphene and carbon paste. This nanocomposite cathode film based capacitor showed ultralow equivalent series resistance (ESR) ca. 12 mΩ and exhibited better capacitance-frequency performance than the PEDOT based capacitor. The leakage current investigation revealed that the device encapsulation process does not influence capacitor leakage current, indicating the excellent mechanical strength of PEDOT-graphene films. The graphene showed a distinct protection effect on the dielectric layer from possible mechanical damage. This high conductivity and mechanical strength graphene based conducting polymer nanocomposites indicated a promising application future for organic electrode materials.