Electronic Conductivity of Polypyrrole−Dodecyl Benzene Sulfonate Complexes

Enhancement of NO2 Gas Sensing Properties of Polypyrrole by Polarization Doping with DBS: Experimental and DFT Studies

A new technique of polarization doping was adopted to improve NO2 gas sensing properties of the polypyrrole (PPy) sensor. PPy nanosheets polarization doped with sodium dodecyl benzenesulfonate (SDBS) were synthesized by low-temperature polymerization. The semiagglomerated PPy nanosheets were well-dispersed and a large specific surface areas due to the introduction of dodecyl benzenesulfonate (DBS). The DBS doped PPy sensor shows excellent NO2 sensing performance. Polarization of sulfonate ions to PPy enhanced the adsorption ability of NO2 with the synergistic effect of NO2. The adsorption energy (-0.676 eV) and electron transfer (0.521 |e|) of PPy to NO2 increased greatly after doping. An unoccupied electron state is observed in the valence band electron structure of PPy/DBS after the adsorption of NO2 by calculations of Density Functional Theory (DFT). The intermolecular synergy between NO2 and PPy/DBS causes a strong polarization, resulting in a high polarization potential, which enhances the NO2 sensing performance of PPy sensor. It is of great significance to develop NO2 detection device based on PPy that works at room temperature.

Role of Polyoxometalate Contents in Polypyrrole: Linear Actuation and Energy Storage

A combination of polyoxometalates with polypyrrole is introduced in this work. Our goal was to include phosphotungstic acid (PTA) in different molar concentrations (0.005, 0.01, and 0.05 M) in the electropolymerization of pyrrole doped with dodecylbenzene sulfonate (DBS) and phosphotungstinates (PT), forming PPy/DBS-PT films. Scanning electron microscopy (SEM) revealed that the PPy/DBS-PT films became denser and more compact with increasing PTA concentrations. The incorporation of PT in PPy/DBS was analyzed using Fourier-transform infrared (FTIR) and energy dispersive X-ray (EDX) spectroscopy. The linear actuation in cyclic voltammetry and potential square wave steps in an organic electrolyte revealed increasing mixed actuation, with major expansion upon oxidation found for PPy/DBS-PT films with a PTA concentration of 0.005 M. Best results of a strain of 12.8% and stress at 0.68 MPa were obtained for PPy/DBS-PT (0.01 M). The PPy/DBS-PT films polymerized in the presence of 0.05 M of PTA and showed main expansion upon reduction, changing the actuation direction. Chronopotentiometric measurements of PPy/DBS-PT samples were conducted to determine the specific capacitance optimal for a 0.01 M PTA concentration in the range of 80 F g⁻¹ (±0.22 A g⁻¹).

Metal–organic architectures driven by a multifunctional 6-aminouracil spacer: structures, noncovalent interactions, and conductivity

Three new coordination polymers were assembled from a multifunctional 6-aminouracil building block and their structural features & functional properties were investigated.

Electrically Switchable Monostable Actuatoric Polymer-Based Nanovalve Arrays with a Long-Term Stability

Here we present a novel electrically switchable nanovalve array based on an intrinsic conductive polymer that has the capabilities to change its volume depending on its redox state. The polymer is created by anodic deposition of a sodium dodecylbenzenesulfonate (DBS)-doped polypyrrole (PPy). Optimization of the DBS-doped PPy layers revealed an actuatoric performance of up to 10% out of plane volume change. More interestingly, the electrochemical characterization revealed an actuatoric monostable polymer that could be used to fabricate nanovalve arrays that have a native opened state when no potential is applied and that can be closed when a reductive potential is applied. As a proof of concept, Atto488-labeled biotin (Biotin-Atto488) was used as a model compound and defined nanovalve arrays with nanopores in the range of 10 nm in diameter (opened state) were fabricated. Afterward, we were able to successfully prove the functionality of our nanovalve array by monitoring the flow-through rates of the Biotin-Atto488. More strikingly, we could demonstrate for the first time the robust and long-term stability of our nanovalve array without any performance loss for at least 72 h and retention capabilities of up to 90%. Furthermore, the demonstrated long-term stability was achieved under biocompatible conditions without the need of toxic dopant supplementation of the flow-through solution. Thus, our novel functional long-term stable nanovalve array offers the capabilities for practical applications.

Field-effect-transistor sensor based on enzyme-functionalized polypyrrole nanotubes for glucose detection

We describe the detection of glucose based on a liquid-ion gated field-effect transistor configuration in which enzyme-functionalized polypyrrole nanotubes are employed as the conductive channel. First of all, carboxylated polypyrrole nanotubes (CPNTs) were successfully fabricated by the chemical polymerization of an intrinsically functionalized monomer (pyrrole-3-carboxylic acid, P3CA) without degradation in major physical properties. The CPNTs possessed not only well-defined functional groups but also electrical properties comparable to nonsubstituted polypyrrole. Importantly, the carboxylic acid functional group can be utilized for various chemical and biological functionalizations. A liquid-ion gated FET sensor was readily constructed on the basis of the chemical functionality of CPNTs. In the first stage, the CPNTs were immobilized onto a microelectrode substrate via covalent linkages. It was noteworthy that the covalent immobilization allowed high-quality contact between the nanotubes and the microelectrodes in the liquid phase. The second stage involved the covalent binding of glucose oxidase (GOx) enzyme to the nanotubes. The covalent functionalization generally provides excellent enzymatic activity and thermal stability. The fabricated FET sensor provided real-time response (an increase in source-drain current) and high sensitivity toward the various concentrations (0.5-20 mM) of glucose. The enzymatic reaction product, hydrogen peroxide, played pivotal roles in modulating the charge transport property of CPNTs.