Temperature effect on conducting polyaniline salts: Thermal and spectral studies

Synthesis and characterization of a nanostructure conductive copolymer based on polyaniline and polylactic acid as an effective substrate in proteins impedimetric biosensing

Despite of all the developments in DNA microarray technology, there is not sufficient knowledge about protein abundance or their function in processes such as proteolysis, phosphorylation. Therefore, there is a significant need for direct detection and quantification of proteins, especially in processes such as proteomics, drug design and disease prediction. The present work introduce the new generation of polymeric substrate based on polyaniline and, polylactic acid, which it was used for impedimetric sensor in detection of proteins in particular for bovine serum albumin (BSA). In this copolymerization, the polylactic acid-block-polyaniline copolymer (PLA-b-PANI) was synthesized to attach polylactic acid and polyaniline using epichlorohydrin as a coupling agent. The structure of synthesized compounds in all steps, were confirmed by FT-IR and, 1H-NMR. The thermal properties and, morphology were analyzed by DSC, TGA, and, SEM. Also the electrochemical characteristics of fabricated PLA-b-PANI electrode were investigated by Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). The results demonstrated that morphology of the PLA-b-PANI is sphere shape nanoparticles with dimension less than 100 nanometer diameters and, reasonable thermal properties. PLA-b-PANI was used to modify a screen-printed carbon electrode (SPCE) to fabricate a BSA impedimetric sensor. In order to increase the performance of the proposed impedimetric sensor, optimization of incubation time, pH and amount of PLA-b-PANI were investigated. The results show that the impedimetric sensor has the highest response when the electrode surface is covered with 5 microliters of PLA-b-PANI, and is incubated in BSA solution with pH 6.5 for 5 min. Impedimetric results showed that the PLA-b-PANI has excellent properties in reducing the charge transfer resistance and increasing the electron charge transfer rate. The final impedimetric sensor exhibited good repeatability, reproducibility, and chemical stability within the linear concentration range of 0.1-20 μg L-1 of BSA, and a detection limit of 0.05 μg L-1.

Atmospheric Pressure Plasma Polymerisation of D-Limonene and Its Antimicrobial Activity

Antibacterial coating is necessary to prevent biofilm-forming bacteria from colonising medical tools causing infection and sepsis in patients. The recent coating strategies such as immobilisation of antimicrobial materials and low-pressure plasma polymerisation may require multiple processing steps involving a high-vacuum system and time-consuming process. Some of those have limited efficacy and durability. Here, we report a rapid and one-step atmospheric pressure plasma polymerisation (APPP) of D-limonene to produce nano-thin films with hydrophobic-like properties for antibacterial applications. The influence of plasma polymerisation time on the thickness, surface characteristic, and chemical composition of the plasma-polymerised films was systematically investigated. Results showed that the nano-thin films deposited at 1 min on glass substrate are optically transparent and homogenous, with a thickness of 44.3 ± 4.8 nm, a smooth surface with an average roughness of 0.23 ± 0.02 nm. For its antimicrobial activity, the biofilm assay evaluation revealed a significant 94% decrease in the number of Escherichia coli (E. coli) compared to the control sample. More importantly, the resultant nano-thin films exhibited a potent bactericidal effect that can distort and rupture the membrane of the treated bacteria. These findings provide important insights into the development of bacteria-resistant and biocompatible coatings on the arbitrary substrate in a straightforward and cost-effective route at atmospheric pressure.

Adsorption, Equilibrium Isotherm, and Thermodynamic Studies towards the Removal of Reactive Orange 16 Dye Using Cu(I)-Polyaninile Composite

To overcome some of the limitations of activated carbon like efficiency, cost-effectiveness, and reusability, the present work deals with Cu(I)-based polyaniline (PANI) composite for the removal of reactive orange 16 (RO16) dye. Following the synthesis and characterization of formed Cu(I)-PANI composite, the batch experiments performed for the removal of RO16 dye indicated that the composite has the capacity to reduce the coloring from RO16. The experiments were conducted for the study of effects against changes in pH, time, and dose at room temperature, where we observed for a pH impact on the dye adsorption capacity in the range of 2–12. Among all, the optimal RO16 removal was found to be 94.77% at a pH of 4 and in addition, the adsorption kinetics confirmed to be pseudo-second-order with more suitability towards the Langmuir isotherm, where it is presumed to be the formation of a monolayer of dye molecule at the homogeneous absorbent surface. The calculated maximum capacity, q_m, determined from the Langmuir model was 392.156 mg/g. Further application of isotherms to attain thermodynamic parameters, a slight positive value of ΔS° for RO16 adsorption was observed, meaning that there is an increased randomness in the irregular pattern at the specific Cu(I)-PANI interface for an adsorption process. This mechanism plays an essential role in maintaining the effects of water pollution; and, based on the analysis therefore, it is prominent that the Cu(I)-PANI composite can be employed as a promising and economical adsorbent for the treatment of RO16 and other dye molecules from the sewage in wastewater.

A synthesized ternary polymer composite and its use for SPE of trace metals in Coffee, tea and legumes

A new synthesized ternary polymer composite, polystyrene/polyacrylonitrile/polyindole (PSt/PAN/PIN), was used as an adsorbent. The structure of synthesized composite was supported by FTIR, BET, X-RD, TGA, SEM and AFM technique. A SPE method with synthesized composite was developed for the preconcentration of chromium, copper, iron, manganese, lead and zinc ions. The adsorption capacity were found in the range of 37.4-56.7 mg g^-1. Under the best conditions, the preconcentration factor of method was found as 100. Relative standard deviation was found at ≤ 3.3% (n = 11). The detection limits of analytes were obtained as: 0.9 μg L^-1 for Cr(III), 1.2 μg L^-1 for Cu(II), 2.0 μg L^-1 for Fe(III), 1.4 μg L^-1 for Mn(II), 0.9 μg L^-1 for Pb(II) and 2.0 µg L^-1 for Zn(II). Firstly, this SPE method was applied to certified reference material, and than coffee, tea, legumes. The trace metals was analyzed by flame atomic absorption spectrometry.

Polyaniline Hybrid Nanofibers via Green Interfacial Polymerization for All-Solid-State Symmetric Supercapacitors

In this study, we report an enormously simple green approach for the synthesis of polyaniline hybrid (PANI-SO) nanofibers in emeraldine salt form. We have carried out the synthesis via an interfacial polymerization method using vegetable oil as an organic phase instead of the commonly used solvents like CHCl₃, CCl₄, etc. Characterization techniques such as Fourier transform infrared (FTIR), UV-visible, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) have been used for studying the synthesized polyaniline hybrid nanofibers. An interesting observation is the crystallization of small organic molecules in the PANI matrix. PANI-SO shows a pseudocapacitance behavior with a capacitance value of 302 F g^-1 at a current density of 1 A g^-1. In addition, the material shows an energy density of 26.8 W h kg^-1 and a maximum power density of 402.6 W kg^-1. Furthermore, the PANI-SO electrode maintains about 84% of the initial capacitance after 1000 cycles. Similarly, the PANI-SO symmetric solid-state supercapacitor shows an areal capacitance of 118.7 mF cm^-2 and retains a stability of 80% even after 1000 cycles. Thus, the PANI-SO electrode shows a good cyclic performance, which implies the structural stability of PANI-SO nanofibers. The electrochemical properties of PANI-SO are compared with those of PANI nanofibers synthesized by taking CHCl₃ as the organic phase and keeping all other parameters identical. PANI-SO is observed to be a superior material compared to the latter one. All electrochemical analyses show that the PANI synthesized using cooking soyabean oil (PANI-SO) is an effective supercapacitor material.

Role of Reaction Time on the Electrical Conductivity, Thermal Stability and Photoluminescence Property of Polyanilne Nanofibers

Direct evidence of the control of yield, thermal stability and photoluminescence property of the polyaniline (PANI) nanofibers have been reported by systematically varying the reaction time in the range of 2–6 hours (h) in the synthesis process. Both FTIR and UV–visible spectra revealed the formation of PANI fibers for all synthesis batches. The mass of the obtained PANI was increased with the increase of reaction time from 2 to 6 h. FESEM data confirmed the formation of PANI in nanofibers form for all the synthesis batches. TGA data showed that the highest thermal stability of PANI nanofibers could be obtained for the 4 h reaction time. PL data indeed showed the variation of luminescence intensity of PANI with the reaction time which indicate the formation of different quality fibers in terms of their π conjugation. Thus the three main results can be summarized: one is the increase of PANI fibers yield and another two are the thermal stability and luminescence property modification which shows that such properties of PANI can be controlled by varying the reaction time of the synthesis process.

Evaluation of Polyaniline for Packaging Applications

Polyanilines having two different morphologies (nanorods for NR-PANI and granular for G-PANI) were synthesized and subjected to thermal treatment. NR-PANI and G-PANI were thermally stable up to 300 and 250 °C respectively. Upon thermal treatment, both the polyanilines exhibited suppressed conductivity and free radical scavenging capacity. The polyanilines also became completely amorphous after treatment above 200 °C.

Facile synthesis of polyaniline-sodium alginate nanofibers

This work demonstrates a facile route to the synthesis of large quantities of uniform polyaniline-sodium alginate (PANI-SA) nanofibers template-guided by SA. This approach is an easy, inexpensive, environmentally friendly, and scalable one-step method to produce uniform nanofibers with controllable average diameters in bulk quantities. We started with biopolymer-monomer complexes formed between the carboxylic groups of SA and the amino group of an organic monomer (aniline). When ammonium persulfate was added, such polymer-monomer complexes could be polymerized. Then, polyaniline-sodium alginate nanofibers with uniform diameters from 40 to 100 nm were successfully obtained in a high yield. The resultant PANI-SA nanofibers were characterized by means of different techniques, such as ultraviolet-visible spectroscopy, thermogravimetric analysis, wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopy methods. The mechanism governing the formation of the polyaniline-sodium alginate nanofibers is discussed.