Vapor Phase Polymerization Research Articles

Tunable Structural Color Images by UV-Patterned Conducting Polymer Nanofilms on Metal Surfaces.

Precise manipulation of light-matter interactions has enabled a wide variety of approaches to create bright and vivid structural colors. Techniques utilizing photonic crystals, Fabry-Pérot cavities, plasmonics, or high-refractive-index dielectric metasurfaces have been studied for applications ranging from optical coatings to reflective displays. However, complicated fabrication procedures for sub-wavelength nanostructures, limited active areas, and inherent absence of tunability of these approaches impede their further development toward flexible, large-scale, and switchable devices compatible with facile and cost-effective production. Here, a novel method is presented to generate structural color images based on monochromic conducting polymer films prepared on metallic surfaces via vapor phase polymerization and ultraviolet (UV) light patterning. Varying the UV dose enables synergistic control of both nanoscale film thickness and polymer permittivity, which generates controllable structural colors from violet to red. Together with grayscale photomasks this enables facile fabrication of high-resolution structural color images. Dynamic tuning of colored surfaces and images via electrochemical modulation of the polymer redox state is further demonstrated. The simple structure, facile fabrication, wide color gamut, and dynamic color tuning make this concept competitive for applications like multifunctional displays.

Photocatalytic, Oxygen-Generating PEDOT/Nano-Ni Composite film with Sustained High Activity

Composite PEDOT films, prepared using vapour phase polymerisation incorporating with nanoparticulate Ni (‘nano-Ni’) on FTO glass have been studied as photoelectrocatalysts of water oxidation in 0.2 M Na2SO4 electrolyte at different pH. The PEDOT/nano-Ni Films proved to be active at high pH generating current densities at 0.80 V (vs Ag/AgCl) of 0.655 mA/cm2 (including a photocurrent of 0.4 mA/cm2) under light illumination of 0.25 Sun. A variety of techniques were used to study and characterized the films, including: cyclic voltammetry, chronoamperograms, gas chromatography and scanning electron microscope.

Flexible, biocompatible, and electroconductive Polyurethane foam composites coated with graphene oxide for ammonia detection

Polyurethane foam (PUF) composites are of great interest in various polymer applications due to their tunable mechanical and stretchable properties, and easy fabrication. In this study, flexible, biocompatible, and electroconductive PUF composites (PUF-graphene oxide (GO), PUF-polypyrrole (PPy)-GO, and PUF-poly(3,4-ethylenedioxythiophene) (PEDOT)-GO) were synthesized using a sequential procedure of vapor phase polymerization (VPP) and GO impregnation. First, hydroxyl groups in polytetramethylene ether glycol (PTMEG) and diisocyanate functional groups in polymeric methylene diphenyl diisocyanate (PMDI) underwent a reaction to generate urethane bonds. Then, by adding water, CO2 gas was used during the reaction of isocyanate to generate bubbles creating a porous interconnected foam. Conductive polymers (CPs) such as PPy and PEDOT were vapor-phased polymerized on the synthesized PUF matrix. Then, these composites were integrated with GO by impregnation on the surface of PUF-conductive polymers (CP). The flexible, and electroconductive PUF composites were analyzed and compared with respect to pore size distribution, mechanical, thermal, and electrical properties. Indirect biocompatibility and cell proliferation with PUF composites were also evaluated for 7 days. Among the PUF composites, the PUF-PPy-GO was further investigated as an NH3 gas sensing material and showed high values in sensitivity coefficients as well as the selectivity coefficients, demonstrating the sensor's utility in determining NH3 gas incidence.

Regulating monomer assembly to enhance PEDOT capacitance performance via different oxidants

The development of poly(3,4-ethylenedioxythiophene) (PEDOT) with high specific capacitance is the key to pursuing high-performance supercapacitors, and the electrochemical properties of PEDOT are closely related to the oxidation degree and conjugated chain length of its molecular chain. In this work, the influences of various oxidants (FeCl3, Fe(Tos)3 and MoCl5) on the molecular chain structure and capacitive properties of PEDOT via vapor phase polymerization were systematically investigated. Fe(Tos)3 can significantly improve the degree of oxidation and the length of the conjugated chain of PEDOT compared to FeCl3 and MoCl5, enhancing the conductivity and providing more active sites for Faraday reaction. Therefore, the PEDOT/P(Fe(Tos)3) electrode displays a considerable conductivity of 73 S cm-1, high areal capacitance (419 mF cm-2) and excellent electrochemical stability under the different bent state. Moreover, the conjugated structure strengthens the interaction between PEDOT chains, achieving good cycle stability. Therefore, Fe(Tos)3 is an ideal oxidant for obtaining high-performance PEDOT electrode materials.

Structural Tuning of a Flexible and Porous Polypyrrole Film by a Template-Assisted Method for Enhanced Capacitance for Supercapacitor Applications.

Constructing a rational electrode structure for supercapacitors is critical to accelerate the electrochemical kinetics process and thus promote the capacitance. Focusing on the flexible supercapacitor electrode, we synthesized a three-dimensional (3D) porous polypyrrole (PPy) film using a modified vapor phase polymerization method with the use of a porous template (CaCO3). The porous design provided the PPy film with an improved surface area and pore volume. The porous PPy film electrode was studied as a binder-free electrode for supercapacitors. It was found that the abundant interpenetrated pores created by the CaCO3 templates within the 3D framework are beneficial to overcoming the diffusion-controlled limit in the overall electrochemical process. It was revealed by electrochemical investigation that a more pseudocapacitive contribution than diffusion-controlled process contribution was observed in the total charge in the redox reaction. The galvanostatic charge/discharge (GCD) measurements showed that the optimized 3D porous PPy film electrode delivered a high capacitance of 313.6 F g-1 and an areal capacitance of 98.0 mF cm-2 at 1.0 A g-1 in a three-electrode configuration, which is nearly three times that of the dense counterpart electrode synthesized in the absence of the CaCO3 template. A specific capacitance of 62.5 F g-1 at 0.5 A g-1 and 31.1 F g-1 at 10 A g-1 was obtained in a symmetric capacitor device. In addition, the porous structure provided the PPy film with the attractive capability of accommodating the volume change during the doping/dedoping process. This is essential for the PPy film to maintain a long cycling life in a practical operation for a supercapacitor. It turned out that a high capacitance retention up to 81.3% after 10,000 GCD cycles was obtained for the symmetric supercapacitor device with the 3D porous PPy electrode (57.1% capacitive retention was observed for the dense PPy electrode). The strategy and the insight analysis are expected to provide valuable guidance for the design and the synthesis of flexible and wearable film electrodes with high performance.

Superior Electrochemical Properties of Ni-Rich LiNi0.85Co0.05Mn0.10O2 Cathode with the Stable Polypyrrole Coating and Boron Doping for Li-Ion Batteries

Ni-rich cathode materials have attracted much attention due to the high energy density and low cost. However, the poor cycling performance and low rate capacity have produced a serious impact on the practical commercial application. In this work, the B3+ incorporation and polypyrrole coating were both applied to enhance the electrochemical properties of LiNi0.85Co0.05Mn0.10O2 by using the co-precipitation process followed by a chemical vapor phase polymerization way. Herein, the B3+ incorporation into crystal structure could enlarge the lattice spacing, contributing to accelerating the Li+ insertion/extraction speed and enhancing the structural stability during cycling. The polypyrrole surface coating played a great effect on preventing cathode surface from the electrolyte erosion owing to a shield of polypyrrole. As a result, a maximum discharge capacity of 129.8 mAh g−1 at 5 C high rate and prominently enhanced cycling performance with capacity retention of 90.1% after 300 cycles were acquired for the Polypyrrole coated LiNi0.835Co0.05Mn0.10B0.015O2. By comparison, the pristine LNCMO cathode demonstrated a fast decaying capacity and delivered a capacity retention of only 81.9%.

A comparative study between vapor phase polymerized PPy and PEDOT - Thermoplastic polyurethane composites for ammonia sensing

In this study, in situ vapor phase polymerization (VPP) of (1) 3,4-ethylenedioxythiophene (EDOT) and (2) pyrrole (Py) on an oxidant-impregnated thermoplastic polyurethane (TPU) substrate was conducted to produce a (1) PEDOT-TPU hybrid film and (2) PPy-TPU hybrid film. Scanning electron microscopy, atomic force microscopy, and energy dispersive x-ray spectroscopy confirmed the formation of uniform, rough surfaces of PPy and PEDOT on the TPU matrix. Both PPy-TPU and PEDOT-TPU films showed excellent thermal stability across the temperature range of 300 °C–400 °C and enhanced mechanical properties, depicted by very high stress and strain values. The performance of these hybrid films to detect ammonia (NH3) gas was investigated and then optimized under the effects of varying temperature, ammonia concentration, and monomer type used. The PEDOT-TPU and PPy-TPU showed remarkable sensitivity to NH3 gas, with coefficients of variation of 0.9858 and 0.9653, respectively. Particularly, the PEDOT-TPU sensor showed higher responsiveness to NH3 at higher operating temperatures owing to its higher surface roughness and thermal stability. These flexible, stretchable, smart conducting polymer composite materials fabricated using VPP are therefore potential candidates for monitoring toxic and non-toxic gases.

Vapor phase polymerization for electronically conductive nanopaper based on bacterial cellulose/poly(3,4-ethylenedioxythiophene)

Eco-friendly conductive polymer nanocomposites have garnered attention as an effective alternative for conventional conductive nanocomposites. Here, we report the fabrication and optimization of flexible, self-standing, and conductive bacterial cellulose/poly(3,4-ethylene dioxythiophene) (BC/PEDOT) nanocomposites using the vapor phase polymerization (VPP) method. Eco-friendly bacterial cellulose (BC) is used as a flexible matrix, and the highly conductive PEDOT polymer is introduced into the BC matrix to achieve electronic conductivity. We demonstrate that vapor phase polymerized BC/PEDOT composites exhibit more than 10 times lower sheet resistance (18 Ω/square) compared to solution polymerized BC/PEDOT (188 Ω/square). The resultant BC/PEDOT fabricated could be bent up to 100 times and completely rolled up without a notable decrease in electronic performance. Moreover, bent BC/PEDOT films enable operation of a green light-emitting diode (LED) light, indicating the flexibility and stability of conductive BC/PEDOT films. Overall, this study suggests a strategy for the development of eco-friendly, flexible, and conductive nanocomposite films.

Tri-layer architectured epoxy composites with high electrical permittivity

In this work, epoxy composites filled with polypyrrole (ppy) coated paddy straw micro particles exhibiting high electrical permittivity were prepared. Oxidative vapour phase polymerization was used to obtain thin ppy coating over straw particles. These single layered epoxy composites exhibited high electrical permittivity and were further used to prepare tri-layer architectured composites in which an epoxy-graphene (−ve k) composite layer was stacked in-between two epoxy-ppy-straw (+ve k) composite layers. The layered composites displayed an even higher electrical permittivities, 124.2 and 227.7 (1 kHz) and suppressed tanδ 0.055 and 0.5 at 33 wt% and 38 wt% filler concentrations respectively. The tanδ showed strong frequency dependence and their minima shifted to higher frequencies. The thickness of +ve k layers were reduced progressively and corresponding permittivities were recorded which showed a linear increase as the thickness ratio of layers (−ve k/+ve k) increased.

Novel vapor polymerization for integrating flame retardant textile with multifunctional properties

Vapor-phase polymerization (VPP) of pyrrole is a facile, and salutary technique for enhancing multilateral properties of substrates for various applications. Herein, a facile, and eco-friendly VPP of pyrrole on the cotton/polyester substrate using the silver nitrate has been primarily introduced. The polymerization time and the oxidant concentration have been varied to obtain new composite textiles. The redox reaction that happened between silver ions and pyrrole monomer results in forming polypyrrole-silver composite (Ppy-Ag) as a coating layer for obtaining smart textiles with versatile properties. The structure and morphology of the as-formed composite were assured on the surface of the textile using FTIR, XRD, EDX, TGA, and SEM. The conductivity, antibacterial, and flammability of the as-developed textiles were estimated. The coated textile achieved superior conductivity features as the electrical resistance was recorded as 0.0218 kΩ which is much lower compared to the pure textile (2770 kΩ). Additionally, the composites accomplished an inhibition zone with the diameters of 25, and 28 mm for E.coli, and S. aureus, respectively confirming a supreme antibacterial behavior. Also, they fulfilled an unexpected rate of burning 80.6 mm/min with concerning to the virgin textile (149.3 mm/min) achieving flame retardancy by 46 %.

Electro-responsive epoxy-polypyrrole-cotton composites with enhanced flexural strength and water resistance

Functional epoxy composites reinforced with cotton fabric layers coated with conducting polypyrrole (ppy) were prepared. Oxidative vapor phase polymerization was used to obtain thin coating of ppy. When embedded within the epoxy resin (2, 4 and 6 layers), the resulting composites showed improved flexural strength (up to 20.7 %, 26.9 % and 19.7 % for respective layers) and highly reduced water absorption (up to 61.2 %) after 24 h at 35 °C than those containing uncoated cotton layers. The conducting fabric layers allowed composites to heat upon voltage application via Joule’s effect. Statistical modelling revealed good correlation with experimental data and the influence of number of fabric layers, electrode area and applied voltage on peak temperature was studied. Composite with 6 layers showed highest peak surface temperature (92 °C) at 24 V and demonstrated a uni-directional shape recovery (greater than 60 %) when subjected to electric-heating after being deformed previously under load.

Vapor phase polymerized conducting polymer/MXene textiles for wearable electronics.

Multifunctional electronic textiles hold great potential applications in the wearable electronics field. However, it remains challenging to seamlessly integrate the multiple functions on the textile substrates without sacrificing their intrinsic properties. Herein, we report a novel and facile vapor phase polymerization (VPP) and spray-coating strategy towards the construction of a laminated film containing a PEDOT film and Ti3C2Tx MXene sheets on the fiber surface. The fabricated PEDOT/MXene decorated cotton fabrics are integrated with excellent electrochemical performance, joule heating performance, good electromagnetic interference (EMI) shielding, and strain sensing performance. The resultant multifunctional textiles have a low sheet resistance of 3.6 Ω sq-1, and the assembled all-solid-state fabric supercapacitors exhibit an ultrahigh specific capacitance of 1000.2 mF cm-2, which exceeds the state-of-the-art MXene-based fabric supercapacitors. In addition, the PEDOT/MXene modified fabrics exhibit an exceptional joule heating performance of 193.1 °C at the applied voltage of 12 V, high EMI shielding effectiveness of 36.62 dB, and high sensitivity as strain sensors for human motion detection. This work provides a novel strategy for the structure design of multifunctional textiles and will lay the foundation for the development of multifunctional wearable electronics.

Chitosan-supported deep eutectic solvent as bio-based electrolyte for flexible supercapacitor

The aim of this work is demonstration of a solid polymer electrolyte based on choline chloride/lactic acid deep eutectic solvent (DES) entrapped in chitosan (CS) matrix as potential separator for electrochemical energy storage devices. This full bio-based material demonstrates the high ionic conductivity up to 2.5 mS cm−1 and electrochemical stability window of 1.6 V. The polypyrrole-based film electrodes were prepared using CS/DES films as a supporting matrix for vapor phase polymerization of pyrrole. That allows assembling of a supercapacitor with the specific capacitance of 194 mF cm−2 at the current density of 1 mA cm−2.

Highly conductive PEDOT films with enhanced catalytic activity for dye-sensitized solar cells

Low-cost poly (3,4 ethylenedioxythiophene) (PEDOT) films with a high electronic conductivity of 1021 S/cm were successfully deposited via iron oxide-based vapor-phase polymerization and used as a counter electrode (CE) in dye-sensitized solar cells for the first time. Reaching a high efficiency of 8.4%, the CE showed outstanding catalytic activity in iodine/triiodide (I-/I3-) reduction, with a six times lower charge transfer resistance than a standard Pt CE. Combining low cost, easy fabrication, and high electro-catalytic activity, our PEDOT films are a promising replacement for expensive platinum CEs. This efficiency is one of the highest reported among the PEDOT-based DSSC.

Greener synthesis route and characterization of smart hybrid graphene based thin films

Green and innovative approach was developed for synthesis of smart nanocomposites thin films for various applications. As, nanofilm of PANI-NFs of an average size of 50 nm and average film thickness of 160 nm was synthesized using facile one pot step at ambient condition using chemical oxidative polymerization. Then, polypyrrole chain layer was polymerized using solventless vapor phase polymerization method on surface of PANI-NFs thin film producing interesting nanocomposite thin film PANI-NF-PPY of an average film thickness of 440 nm. The polypyrrole synthesis reaction times were altered and optimized. Furthermore, high quality graphene sheets were synthesized by direct exfoliation of commercial graphite using ultrasonication. Afterwards, decorated with TiO2NPs of an average size of 21 nm and then decorated in PANI-NFs nanocomposite surface through in situ synthesis route producing two dimension (2D) interesting nanocomposite thin film. Additionally, polypyrrole layer was polymerized on the top surface of the decorated PANI-NF-GR-TiO2NPs via vapor phase producing smart and innovative 2D multifunctional thin film. The developed 2D nanocomposite thin film is interesting and potential for energy storage and other various applications. This study open new trend for design and green synthesis of 2D nanocomposite thin films based on various nanomaterials dimension for charge storage applications and various surface applications.

Combining Electrospinning and Vapor-Phase Polymerization for the Production of Polyacrylonitrile/ Polypyrrole Core-Shell Nanofibers and Glucose Biosensor Application.

In this work, polyacrylonitrile (PAN) nanofiber mats coated with conductive polypyrrole layers were produced at the surface of gold electrodes by a two-step approach combining electrospinning and vapor phase polymerization. In the first step, smooth and uniform PAN fibers exhibiting an average diameter of 650 ± 10 nm were generated through electrospinning of 12 wt% PAN solutions. The electrospun PAN fibers were impregnated with iron(III)tosylate (FeTos), annealed at 70°C and used as a robust and stable template for the growth of a thin layer of conductive polymer by co-polymerizing pyrrole (Py) and pyrrole-3-carboyxylic acid (Py3COOH) vapors under nitrogen atmosphere. The carboxyl groups introduced in polypyrrole coatings enabled further covalent binding of a model enzyme, glucose oxidase. The effect of different parameters (concentration of FeTos into the immersion solution, time of polymerization, Py/Py3COOH molar ratio) on the PAN/PPy/PPy3COOH/GOx impedimetric biosensor response was investigated. In the best conditions tested (immersion of the PAN fibers into 20 wt% FeTos solution, polymerization time: 30 min, 1:2 Py/Py3COOH ratio), the biosensor response was linear in a wide range of glucose concentration (20 nM−2μM) and selective toward ascorbic and uric acids. A very low limit of detection (2 nM) compared to those already reported in the literature was achieved. This value enables the determination of glucose in human serum after a large dilution of the sample (normal concentrations: 3.6 mM−6.1 mM range).

Controllable vapor phase polymerization of PEDOT films using imidazole as an inhibitor and their electrical and electrochromic properties

PEDOT films were fabricated by vapor-phase polymerization (VPP) with different inhibitor contents in oxidant-containing solutions, and were characterized by X-ray diffraction, Raman spectroscopy, UV/vis transmittance spectra, atomic force microscopy, electrical conductivity and electrochromic measurements. The imidazole which serves as an inhibitor plays key roles on the polymerization reaction, and varying its content results in drastically different properties of the PEDOT films. In the imidazole/Fe(III) p-toluenesulfonate (Im/Fe) weight ratio range of 0∼0.25, the rate of polymerization can be significantly slowed down by increasing the Im/Fe ratio. The optimum Im/Fe ratio of 0.1 and polymerization time of 3 h results in PEDOT films with the highest conductivity on glass substrate (626 S/cm). Higher doping level is found in PEDOT films fabricated with the Im/Fe ratio above 0.1, causing low conductivity due to their loose morphology. The electrochromic properties of the films can be enhanced by prolonging the polymerization time to 3 h. It is found that the transmittance difference at 550 nm is above 10 % in PEDOT films fabricated with 3 h of polymerization. An electrochromic device is assembled and its coloring time is less than 3 s.

Epoxy‐Polypyrrole‐Cotton Tertiary Composite with Electro‐Tunable Stiffness

AbstractIn this work, a tertiary epoxy composite reinforced with polypyrrole (PPy) coated cotton fabric layers exhibiting electrical voltage induced thermally tunable stiffness is reported. The thin coating of PPy over cotton fabric is accomplished via oxidative vapor phase polymerization that allows creation of an active thin layer over the fibers without affecting their mechanical properties. Six such functional layers are stacked within an epoxy matrix to prepare the composite that shows in‐plane electrical insulator behavior (volume resistivity > 109 Ω cm) but considerably reduced resistivity by an order of 103 across the cross‐sections. The presence of conductive layers enables the composite to heat via Joule's effect when an electrical voltage is applied across two ends. This causes softening of matrix near the matrix‐reinforcement interface and thereby changing composite's stiffness. On application of variable voltage, a non‐linear decrease of 91% in composite stiffness is observed (6371.2 N m−1 at 0 V to 566.4 N m−1 at 63 V). A stable and tunable mechanical performance of the composite is further demonstrated by cyclic changes in stiffness due to voltage change with recovery up to 95% of original stiffness after 14 continuous cycles.

Stretchable Electronics Based on Laser Structured, Vapor Phase Polymerized PEDOT/Tosylate.

The fabrication of stretchable conductive material through vapor phase polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) is presented alongside a method to easily pattern these materials with nanosecond laser structuring. The devices were constructed from sheets of vapor phase polymerized PEDOT doped with tosylate on pre-stretched elastomeric substrates followed by laser structuring to achieve the desired geometrical shape. Devices were characterized for electrical conductivity, morphology, and electrical integrity in response to externally applied strain. Fabricated PEDOT sheets displayed a conductivity of 53.1 ± 1.2 S cm−1; clear buckling in the PEDOT microstructure was observed as a result of pre-stretching the underlying elastomeric substrate; and the final stretchable electronic devices were able to remain electrically conductive with up to 100% of externally applied strain. The described polymerization and fabrication steps achieve highly processable and patternable functional conductive polymer films, which are suitable for stretchable electronics due to their ability to withstand externally applied strains of up to 100%.

One-step vapor-phase synthesis of transparent high refractive index sulfur-containing polymers.

High refractive index polymers (HRIPs) have recently emerged as an important class of materials for use in a variety of optoelectronic devices including image sensors, lithography, and light-emitting diodes. However, achieving polymers having refractive index exceeding 1.8 while maintaining full transparency in the visible range still remains formidably challenging. Here, we present a unique one-step vapor-phase process, termed sulfur chemical vapor deposition, to generate highly stable, ultrahigh refractive index (n > 1.9) polymers directly from elemental sulfur. The deposition process involved vapor-phase radical polymerization between elemental sulfur and vinyl monomers to provide polymer films with controlled thickness and sulfur content, along with the refractive index as high as 1.91. Notably, the HRIP thin film showed unprecedented optical transparency throughout the visible range, attributed to the absence of long polysulfide segments within the polymer, which will serve as a key component in a wide range of optical devices.