Polymer Polypyrrole Research Articles

Highly sensitive detection of glucose via glucose oxidase immobilization onto conducting polymer-coated composite polyacrylonitrile nanofibers

Current study introduces composite polyacrylonitrile - multiwall carbon nanotubes nanofibers (PAN-MWCNTs NFs) coated with conducting polymers (polypyrrole (PPy) or poly(3,4-ethylenedioxythiophene) (PEDOT)) by chemical vapor deposition for efficient glucose detection. The potential of nanofibrous assemblies and nano-conducting elements in biosensing was explored as pre-processing of NFs with MWCNTs and post-processing with CPs were both employed. These ‘core-shell’ conducting NFs were further employed as platforms for glucose oxidase immobilization for enzymatic detection of glucose. The performance of the biosensors was closely correlated with the concentration of immobilized enzyme and with the type of conducting polymer. The biosensors showed high sensitivities of 92.94 and 81.72 µA/mM.cm−2 for (PAN-MWCNTs)/ PEDOT and (PAN-MWCNTs)/ PPy accompanied by low limit of detection values of 2.30 and 2.38 µM, respectively. Good operational stability was observed throughout twenty-five consecutive measurements, over 90% activity was maintained for both sensors. This study represents proof of concept for the methodology, showcasing the advantages of nanomaterial synthesis for bio-applications. The work was compared thoroughly with previously reported biosensors showing some of the best results reported to date in terms of analytical characteristics.

A Simple and Low-Cost Electrochemical Immunosensor for Ultrasensitive Determination of Calreticulin Biomarker in Human Serum.

An early on time detection of breast cancer significantly affects the treatment process and outcome. Herein, a new label-free impedimetric biosensor is developed to determine the lowest change in the level of calreticulin (CALR), which is a new biomarker of breast carcinoma. The proposed immunosensor is fabricated by using reduced graphene oxide/amino substituted polypyrrole polymer (rGO-PPyNH2 ) nanocomposite modified disposable electrode. The anti-CALR antibodies are first attached on the rGO-PPyNH2 nanocomposite coated electrode through glutaraldehyde crosslinking; the CALR antigens are then immobilized with the addition of CALR antigens to form an immunocomplex on the sensing surface. This immunocomplex induces considerably larger interfacial electron transport resistance (Rct ). The variation in the Rct has a linear relationship with CALR level in the detection range of 0.025 to 75pg mL-1 , with a detection limit of 10.4 fg mL-1 . The suggested biosensor shows high selectivity to CALR, good storage stability (at least 5 weeks) and suitable reproducibility results as shown in quality control chart. The designed immunosensor is utilized to analyze CALR levels in human sera with satisfying results. This immunosensor provides a novel way for the clinical determination of CALR and other cancer biological markers.

How nanoporous silicon-polypyrrole hybrids flex their muscles in aqueous electrolytes: In operando high-resolution x-ray diffraction and electron tomography-based micromechanical computer simulations

Macroscopic strain experiments revealed that Si crystals traversed by parallel, channel-like nanopores functionalized with the muscle polymer polypyrrole exhibit large and reversible electrochemo-mechanical actuation in aqueous electrolytes. On the microscopical level this system still bears open questions, as to how the electrochemical expansion and contraction of PPy acts on to np-Si pore walls and how the collective motorics of the pore array emerges from the single-nanopore behavior. An analysis of in operando X-ray diffraction experiments with micromechanical finite element simulations, based on a 3D reconstruction of the nanoporous medium by TEM tomography, shows that the in-plane mechanical response is dominantly isotropic despite the anisotropic elasticity of the single crystalline host matrix. However, the structural anisotropy originating from the parallel alignment of the nanopores lead to significant differences between the in- and out-of-plane electromechanical response. This response is not describable by a simple 2D arrangement of parallel cylindrical channels. Rather, the simulations highlight that the dendritic shape of the Si pore walls, including pore connections between the main channels, cause complex, inhomogeneous stress-strain fields in the crystalline host. Time-dependent X-ray scattering on the dynamics of the actuator properties hint towards the importance of diffusion limitations, plastic deformation and creep in the nanoconfined polymer upon (counter-)ion adsorption and desorption, the very pore-scale processes causing the macroscopic electroactuation. From a more general perspective, our study demonstrates that the combination of TEM tomography-based micromechanical modeling with high-resolution X-ray scattering experiments provides a powerful approach for in operando analysis of nanoporous composites from the single-nanopore up to the porous-medium scale.

Effect of heteroatoms on structural, electronic and spectroscopic properties of polyfuran, polythiophene and polypyrrole: A hybrid DFT approach

In the present manuscript a brief discussion about the new generation of plastic or polymer also called materials of 21st century was conducted. A comparative study of the structural, electronic and spectroscopic properties of the three heterocyclic polymers polypyrrole, polythiophene and polyfuran in neutral form of particular interest has been carried out using the result of Density Function Theory B3LYP/6-31G (d, p) methods. Also how theoretical methods utilizing quantum chemical calculations can be employed to study various properties of these new generation polymers and what information's can be drawn from them about their structural and electronic properties has been discussed. Our major concern is to study the effect of heteroatom i-e O, N, S on electronic, structural and spectroscopic properties of Furans, Pyrrole and Thiophenes. For this purpose, the important structural properties (geometric parameters, charge analysis) spectroscopic properties (vibrational and VU–vis spectra's) and electronic properties (HOMO, LUMO and band gap) of these polymers are compared. The calculated trend in the values of different properties (electronic, structural and spectroscopic) of the polymers is an excellence agreement with available experimental values. The theoretical calculation predicted the order of more attraction as polythiophene (PTh) ˃ polyfuran (PF) ˃ polypyrrole (PPy) from optimized geometric parameters, the Spectroscopic study predict that the λmax absorption shown in the order of PTh ˃ PF ˃ PPy, the HOMO, LUMO and band gap calculation also go side by side with the result obtained from structural and spectroscopic properties calculation

The effect of electroactive length and intrinsic conductivity on the actuation behaviour of conducting polymer-based yarn actuators for textile muscles

Recently, electrically driven conducting polymer (CP) coated yarns have shown great promise to develop soft wearable applications because of their electrical and mechanical behaviour. However, designing a suitable yarn actuator for textile-based wearables with high strain is challenging. One reason for the low strain is the voltage drop along the yarn, which results in only a part of the yarn being active. To understand the voltage drop mechanism and overcome this issue intrinsically conductive yarns were used to create a highly conductive path along the full length of the yarn actuator. Ag plated knit-de-knit (Ag-KDK) structured polyamide yarns were used as the intrinsically conductive core material of the CP yarn actuators and compared with CP yarn actuators made of a non-conductive core knit-de-knit (KDK) yarn. The CP yarn actuators were fabricated by coating the core yarns with poly(3,4-ethylene dioxythiophene): poly(styrene sulfonic acid) followed by electrochemical polymerization of polypyrrole. Furthermore, to elucidate the effect of the capillarity of the electrolyte through the yarn actuator, two different approaches to electrochemical actuation were applied. All actuating performance of the materials were investigated and quantified in terms of both isotonic displacement and isometric developed forces. The resultant electroactive yarn exhibits high strain (0.64 %) in NaDBS electrolytes as compared to previous CP yarn actuator. The actuation and the electroactivity of the yarn were retained up to 100 cycles. The new highly conductive yarns will shed light on the development of next-generation textile-based exoskeleton suits, assistive devices, wearables, and haptics garments.

Electrochemical assay of acetamiprid in vegetables based on nitrogen-doped graphene/polypyrrole nanocomposites.

Dual-mode electrochemical aptasensor based on nitrogen-doped graphene (NG) doped with the conducting polymer polypyrrole (PPy) nanocomposite is proposed for the determination of acetamiprid. NG/PPy was electrodeposited onto the glassy carbon electrode (GCE) using cyclic voltammetry technique. NG/PPy/GCE showed outstanding electrocatalytic activity for the oxidation of nitrite due to "active region" induced by the charge redistribution of carbon atoms. The ultrasensitive dual-mode biosensor for acetamiprid could be easily developed by coupling acetamiprid aptamers with the NG/PPy hybrid. The specific binding between acetamiprid and the aptamers resulted in the increase of differential pulse voltammetry (DPV) signal change and the decrease of chronoamperometry (CA) signal, and the concentration of acetamiprid could be measured. The working potentials of DPV and CA were - 0.2 ~ 0.4V and - 0.4 ~ 0.4V (vs. SCE), respectively. The dual-mode acetamiprid biosensor showed a wide linear range from 10-12 to 10-7gmL-1, with low detection limits of 1.15 × 10-13gmL-1 and 7.32 × 10-13gmL-1 through DPV and CA modes, respectively. Moreover, owing to high active area and superior conductivity, as well as good electrocatalytic ability, the dual-sensing platform based on NG/PPy nanocomposite supported the quantification of acetamiprid in complex samples. A dual-mode electrochemical aptasensor based on NG/PPy nanocomposite for acetamiprid detection was proposed through both the increase of differential pulse voltammetry (DPV) signal change and the decrease of chronoamperometry (CA) signal of the nitrite oxidation electrocatalyzed by NG/PPyn in sensors and biosensors.

Electrochemical Performance of Fe2O3@PPy Nanocomposite as an Effective Electrode Material for Supercapacitor

Herein, we offer the study on the conductive polymer of polypyrrole and iron oxide (Fe2O3@PPy) nanocomposites, which are prepared via a simple chemical oxidation method for energy storage applications. The synthesized nanocomposites are confirmed by the physico-chemical properties through Fourier Transform Infra-red Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS) results along with Electrochemical Impedance Spectroscopy (EIS), Cyclic Voltammetry (CV), Galvanostatic Charge–Discharge (GCD) and stability analyses. The surface morphological studies of SEM and high TEM images substantiated the formation of Fe2O3@PPy nanocomposite via the polymerization process. The prepared Fe2O3@PPy nanocomposites deliver at a specific capacity of 395.45 C g−1 at 5 mV s−1 scan rate. Moreover, Fe2O3@PPy nanocomposite shows outstanding cycling stability of capacity 94.3% even after 10000 cycles of charge-discharge at the highest current density value of 10 A g−1. The remarkable electrochemical energy storage manner of as-synthesized Fe2O3@PPy nanocomposite is considered a potential electrode for supercapacitor application. The higher electrochemical performance of this Fe2O3@PPy nanocomposite it’s suitable for numerous applications like batteries, sensors, photocatalysts, solar cells and commercial requirements.

Electrically switchable capabilities of conductive polymers-based plasmonic nanodisk arrays.

The electrically dynamic regulation of plasmonic nanostructures provides a promising technology for integrated and miniaturized electro-optical devices. In this work, we systematically investigate the electrical regulation of optical properties of plasmonic Au nanodisk (AuND) arrays integrated with different conductive polymers, polypyrrole (PPy), polyaniline (PANI), and poly(3,4-ethylenedioxythiophene) (PEDOT), which show their respective superiority of electrical modulation by applying the appropriate low voltages. For the hybrid structure of polymer-coated AuND arrays, its reflection spectrum and corresponding structural color are dynamically modulated by altering the complex dielectric function of the covering nanometer-thick conductive polymers based on the electrically controlled redox reaction. Due to the distinct refractive index responses of different polymers on the external voltage, polymer-coated AuND arrays exhibit different spectral variations, response time, and cycle stability. As a result, the reflection intensity of PPy-coated AuND arrays is mainly tailored by increasing optical absorption of the PPy polymer over a broad spectral range, which is distinguished from the wavelength shift of the resonance modes of AuND arrays induced by the other two polymers. Additionally, AuND arrays integrated with both PANI and PEDOT polymers exhibit a rapid switching time of less than 50 ms, which is 5 times smaller than the case of the PPy polymer. Most importantly, PPy-coated AuND arrays exhibit excellent cycle stability over 50 cycles compared to the other two polymers integrated devices. This work demonstrates a valuable technique strategy to realize high-performance polymer-coated dynamically tunable nanoscale electro-optical devices, which has especially significance for smart windows or dynamic display applications.

Polypyrrole-coated Boron-doped Nickel-Cobalt sulfide on electrospinning carbon nanofibers for high performance asymmetric supercapacitors

Although nickel–cobalt bimetallic sulfides have been widely studied for supercapacitor electrodes, how to obtain high specific capacity and cycle stability is still an important challenge. Here, an efficient chemical redox method is used to adjust the crystal and electronic structure of cobalt–nickel sulfide (NCS) via B doping, combined with electrospinning technology and conductive polymer polypyrrole (PPy) coating to facilitate faraday redox reactions and obtain high energy density electrode materials. The resulting composite with boron-doped nickel–cobalt sulfide on electrospinned carbon nanofibers with polypyrrole-coating (PPy@B-NCS/CNF) has a high specific capacity (751.61C/g at 1 A/g) and good cycle stability (82.49 % retention after 4000 cycles at 5 A/g). With PPy@B-NCS/CNF as the positive electrode and activated carbon as the negative electrode, an asymmetric supercapacitor (ASC) is prepared. It has excellent electrochemical properties with a power density of 65.58 Wh kg−1 and an energy density of 819.72 W kg−1. The low-temperature performance test shows high reversibility, which provides the possibility for the development of low-temperature electrolytes. Finally, density functional theory (DFT) explains that B-doped NCS has better electrochemical properties from the energy band and state density.

Sacrificial template induced Fe-, N-, and S-tridoped hollow carbon sphere as a highly efficient electrocatalyst for oxygen reduction reaction

Developing electrocatalysts free from precious metals for oxygen reduction reaction (ORR) is essential for clean energy storage and conversion systems such as metal-air batteries and fuel cells. Herein, hollow-structured Fe-, N-, and S-tridoped carbon (FeNSC) spheres were synthesized by hydrothermal polymerization of polypyrrole, impregnation of iron species, pyrolysis, and a sulfidation processes. During the synthesis procedure, SiO2 nanospheres were used as self-sacrificial templates to achieve a uniform hollow structure. The electronic structure of the highly active Fe–N site was modified by sulfur dopants with relatively low electronegativity, thus efficiently enhancing ORR kinetics. The hollow-structured FeNSC nanospheres exhibited excellent electrocatalytic performance toward the ORR in an alkaline electrolyte, with a remarkable onset potential (0.971 V vs. RHE) and half-wave potential (0.877 V vs. RHE), even outperforming state-of-the-art Pt/C (0.977 and 0.858 V vs. RHE). Furthermore, the FeNSC hollow spheres showed outstanding electrochemical stability over 100 h and methanol tolerance against commercial Pt/C. The findings of this study provide novel insights for designing precious metal-free electrocatalysts with unique hollow structures and heteroatom-doped carbon for energy storage and conversion.

Integrated Polypyrrole-Based Smart Clothing with Photothermal Conversion and Thermosensing Functions for Wearable Applications

Integrated smart clothing with photothermal conversion and thermosensing functions is highly desired for next-generation smart wearable applications. Conducting polymer is a promising material that possesses efficient photothermal conversion performance, great sensitivity to temperature change, and excellent processing properties. In this study, we report a new wearable material using the conducting polymer polypyrrole (PPy) as a photothermal and thermosensing layer and nonwoven fabric as flexible textiles to fabricate integrated PPy-based smart clothing (IPSC). The surface temperature of the prepared IPSC can be as high as 68.4 °C with 808 nm near-infrared (NIR) irradiation at a power destiny of 1 kW/m2. Meanwhile, a temperature resolution of 1 °C can be achieved for IPSC. These superiorities are in favor of fabricating multifunctional smart wearables to satisfy the needs in future life.

Conductivity improvement of magnetite and hematite nanoparticles via admicellar polymerization of polypyrrole

Polypyrrole (PPy) was used to obtain a coating on magnetite (Fe3O4) and hematite (Fe2O3) iron oxide nanoparticles (IONPs). PPy was synthesized on the surface of IONPs by admicellar polymerization for enhancement of electrical conductivity. Low surfactant and monomer levels enabled formation of films on the order of 1 nm thickness. The hydrophobic tendency of the modified IONPs was observed by aggregation in water and exclusion of water molecules. Coated IONPs were characterized by Fourier transform infrared spectroscopic techniques (FT-IR) and scanning electron microscopy (SEM) with particle size distribution analyzed by dynamic light scattering (DLS). Thermal stability of PPy-coated IONPs was investigated by thermogravimetric analysis (TGA). Lastly the magneticity and electrical conductivity of the modified IONPs were analyzed by VSM and multimeter measurements of packed IONPs in a circuit, respectively. Modified IONPs significantly enhanced electrical conductivity with greater effect related to the amount of PPy film coated on the IONP surface. Particle sizes of magnetite and hematite were found within the range between 50 and 2000 nm, depending upon PPy coating. The electrical property was successfully improved, but magnetic properties werenotstatisticallydifferentfrom the bare IONPs. The concentration of Py monomer at 30 mM shown as the critical concentration of both magnetite and hematite had the achievement of the high electrical conductivity.

Conjugated Polymer Polypyrrole Nanostructures: Synthesis and Photocatalytic Applications.

Conjugated polymers (CPs) have been recently widely investigated for their properties and their applications in different fields including photocatalysis. Among the family of CPs, polypyrrole (PPy) has been the most extensively studied owing to its good environmental stability, high electrical conductivity, superior redox properties and easy synthesis. Besides, nanostructured polypyrrole-based nanomaterials are a type of active organic materials for photocatalysis, which is one of their emerging applications. Nanostructuration of polypyrrole can reduce the electron-hole recombination because of short charge transfer distances and reactant adsorption, and product desorption can be enhanced owing to the high surface area offered by nanostructures. This review summarizes synthesis of different nanostructures based on π-conjugated polymer polypyrrole and the latest developments for photocatalytic applications, including degradation of organic pollutants and hydrogen generation.

Re-Stickable Yarn Supercapacitors with Vaper Phase Polymerized Multi-Layered Polypyrrole Electrodes for Smart Garments.

Yarn supercapacitors have attracted significant attention for wearable energy storage due to their ability to be directly integrated with garments. Conducting polymer polypyrrole (PPy) based yarn supercapacitors show limited cycling stability because of the huge volume changes during the charge-discharge processes. In addition, laundering may cause damage to such yarn supercapacitors. Here, the fabrication of PPy-based re-stickable yarn supercapacitors is reported with good cycling stability by employing vapor phase polymerization (VPP) and water-soluble polyethylene oxide (PEO) film as the adhesive layer. VPP duration and cycle are controlled to achieve multi-layered PPy electrodes. The assembled yarn supercapacitors show a good cycling stability with capacitance retention of 79.1% after 5000 charge-discharge cycles. The energy stored in the yarn supercapacitor is sufficient to power a photodetector. After gluing the yarn supercapacitors onto a PEO film, the devices can be stunk on and peeled off the garment to avoid the mechanical stresses during the washing process. Three yarn supercapacitors connected in parallel on PEO film show negative changes in electrochemical performance after 5 sticking-peeling cycles. This work provides a facile way to fabricate PPy-based re-stickable energy storage devices with high cycling stability for smart garments.

Electrical Stimulation Increases Axonal Growth from Dorsal Root Ganglia Co-Cultured with Schwann Cells in Highly Aligned PLA-PPy-Au Microfiber Substrates.

Nerve regeneration is a slow process that needs to be guided for distances greater than 5 mm. For this reason, different strategies are being studied to guide axonal growth and accelerate the axonal growth rate. In this study, we employ an electroconductive fibrillar substrate that is able to topographically guide axonal growth while accelerating the axonal growth rate when subjected to an exogenous electric field. Dorsal root ganglia were seeded in co-culture with Schwann cells on a substrate of polylactic acid microfibers coated with the electroconductive polymer polypyrrole, adding gold microfibers to increase its electrical conductivity. The substrate is capable of guiding axonal growth in a highly aligned manner and, when subjected to an electrical stimulation, an improvement in axonal growth is observed. As a result, an increase in the maximum length of the axons of 19.2% and an increase in the area occupied by the axons of 40% were obtained. In addition, an upregulation of the genes related to axon guidance, axogenesis, Schwann cells, proliferation and neurotrophins was observed for the electrically stimulated group. Therefore, our device is a good candidate for nerve regeneration therapies.

Boosting visible photocatalytic degradation of 2,4-dichlorophenol and phenol efficiency by stable core@shell hybrid Ag3PO4@polypyrrole

In this paper, conjugated conductive polymer polypyrrole molecules were coated on Ag3PO4 nanoparticles by chemical adsorption method. The photocatalytic activity of Ag3PO4 @polypyrrole (Ag3PO4 @PPy) was enhanced significantly with introducing PPy. Under visible light, Ag3PO4 @PPy (1.5 wt%) degraded 100 % of phenol in 12 min and 98.39 % of 2,4-dichlorophenol in 24 min, which was 2.01 times and 1.89 times higher than pure Ag3PO4, respectively. In addition, the degradation activity of core-shell structure catalyst Ag3PO4 @PPy remains 91.26 % after five cycles. The increased stability and activity of as-prepared core-shell Ag3PO4 @PPy was mainly attributed to the synergistic effect of Ag3PO4 and PPy. The high-stability PPy shell inhibits the dissolution of Ag3PO4 nanoparticles. The core-shell structure increases the contact area and a chemical bond was formed on the interface. In addition, the matched energy level structure and the outstanding charge transfer ability of PPy conjugated large π bond accelerates the photo-generated charge separation thereby improves the photoactivity and stability of Ag3PO4.

Mechanisms for enhanced transport selectivity of like-charged ions in hydrophobic-polymer-modified ion-exchange membranes

Effectively removing contaminants or extracting resources from water necessitates selective separation of ions with toxicity or economic value from common ions. Existing ion exchange membranes (IEM) effectively separate ions with opposite charges, but are not optimized for separating ions of like charges. An understanding of ion separation mechanisms is imperative for developing IEMs with improved selectivity between like-charged ions. In this work, we modify a commercial anion exchange membrane (AEM) with a hydrophobic polymer, polypyrrole (PPy), and show that PPy-modified AEM exhibits enhanced transport selectivity of nitrate over both chloride and sulfate. Combining ion sorption experiments and molecular dynamics simulations, we show that the enhanced selectivity between nitrate and chloride is attributed to the decoupling of the inverse relation between the ion partition into and diffusion within the polymer phase, which improves the overall ion transport selectivity between like-charged ions.

Self-Healing, Wet-Adhesion silk fibroin conductive hydrogel as a wearable strain sensor for underwater applications

Wearable strain sensors based on conductive hydrogels have attracted much attention due to their great application potential in fields such as human motion and health monitoring. Under the guidance of application, the design of conductive hydrogels with multiple functions has been developed. However, due to the weakening or elimination of some properties of hydrogels by water molecules, the design of wearable sensors suitable for use in wet or underwater environments and with biosafety is still a challenge. In this paper, the conductive polymer polypyrrole (PPy) combined with silk fibroin (SF) and tannic acid (TA) were introduced into the same gel network by in situ polymerization, and the SF/TA@PPy conductive hydrogel was successfully constructed. The hydrogel has stretchability, skin compliance, antibacterial and biocompatibility properties. In air or underwater, SF/TA@PPy can perform self-healing of mechanical properties, electrical properties, and sensing properties without external stimulation. At the same time, the SF/TA@PPy showed excellent wet adhesion to various materials. It has a wide working range, high strain sensitivity and fast resistance response. It still has stable electrical performance after multiple stretching cycles. As a wearable strain sensor, the SF/TA@PPy can directly adhere to the surface of the human body without the aid of external objects. In addition, it can quickly perceive large strain body movements such as finger joints, wrist joints, elbow joints and knee joints. Changes in small-strain physiological signals such as smile, frown, cough and respiration can also be accurately captured. Body motion detection can be carried out not only in air but also in water. Based on stable electrical properties, SF/TA@PPy can achieve effective underwater information transmission by controlling body movement changes to express the Morse code.

Magnetic Fe3O4/polypyrrole‐salicylaldehyde composite for efficient removal of Mn (VII) from aqueous solution by double‐layer adsorption

AbstractFe3O4 acted as the inner core, conducting polymer polypyrrole (PPy) was wrapped on the surface of Fe3O4, and salicylaldehyde (SA) was grafted to prepare the Fe3O4/PPy‐SA composite. Fe3O4/PPy‐SA exhibited double adsorption properties for Manganese (Mn) (VII) from aqueous solution. And the adsorption properties were systematically investigated. The influences of pH, initial metal ion concentration and temperature on the adsorption performance were measured, showing that the optimal adsorption pH is 2. Moreover, it was found that the adsorption kinetics followed the pseudo second order model, the initial adsorption rate was 46.1467 mg/g/min, and the process was controlled by the liquid film diffusion. The Langmuir adsorption isotherm model could describe the adsorption process well, and the increase of metal ion concentration and temperature was beneficial to the adsorption process. At 288.15 K, the maximum equilibrium adsorption capacity was 471.6981 mg/g. Thermodynamic parameters indicated that the adsorption process was spontaneous, endothermic, and entropy increment. Meanwhile, the cycle test results showed that the adsorbent has good cycle performance and broad application prospects.

Towards electrochemical surface plasmon resonance sensor based on the molecularly imprinted polypyrrole for glyphosate sensing.

In this research the molecular imprinting technology was applied for the formation of glyphosate-sensitive layer. The glyphosate imprinted conducting polymer polypyrrole (MIPpy) was deposited on a gold chip/electrode and used as an electrochemical surface plasmon resonance (ESPR) sensor. The results described in this study disclose some restrictions and challenges, which arise during the development of glyphosate ESPR sensor based on the molecularly imprinted polymer development stage. It was demonstrated, that glyphosate could significantly affect the electrochemical deposition process of molecularly imprinted polymer on the electrode. The results of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and surface plasmon resonance (SPR) have demonstrated that glyphosate molecules tend to interact with bare gold electrode and thus hinder the polypyrrole deposition. As a possible solution, the formation of a self-assembled monolayer (SAM) of 11-(1H-Pyrrol-1-yl)undecane-1-thiol (PUT) before electrochemical deposition of MIPpy and NIPpy was applied. Dissociation constant (KD) and free energy of Gibbs (ΔG0) values of glyphosate on MIPpy and Ppy without glyphosate imprints (NIPpy) were calculated. For the interaction of glyphosate with MIPpy the KD was determined as 38.18±2.33⋅10-5 and ΔG0 as -19.51±0.15kJ/mol.