Vapor Phase Polymerization Research Articles

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.

Layer-by-layer approach to engineer and control conductivity of atmospheric pressure vapor phase polymerized PEDOT thin films

In this work, a fast, simple, low cost, atmospheric pressure based vapor phase polymerization (VPP) of 3, 4-ethylenedioxythiophene (EDOT) has been utilized with controlled substrate temperature. This technique enabled the production of highly electrically conducting thin films of poly (3, 4-ethylenedioxythiophene) (PEDOT). Well-ordered PEDOT films were produced at a nanometer scale by using layer-by-layer technique. Films showed conductance up to 3208 S/cm, and sheet resistance, 20.55 Ω/□ that is close to commercially available indium tin oxide (ITO) coated glasses. FTIR, Raman, and UV–vis studies revealed a polymer in highly conducting form obtained by controlling the VPP method parameters. The surface morphology was studied by atomic force microscopy (AFM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were carried out on PEDOT films without any current collector. The VPP PEDOT films have potential to be used in a variety of transparent electrode applications as well as in supercapacitors.

Conductive and flexible PEDOT-decorated paper as high performance electrode fabricated by vapor phase polymerization for supercapacitor

Currently, electrodes with favorable flexibility, high capacitance and conductivity is vital to the development of supercapacitors. However, it is still a great challenge to manufacture these materials simply and inexpensively. Herein, vapor phase polymerization (VPP) is applied in this work to deposit poly(3,4-ethylenedioxythiophene) (PEDOT) on the flexible paper, which can prepare electrode on a large scale. The fabricated PEDOT/paper possesses porous structure, which can facilitate sufficient contact between electrolyte and electrode material, and benefit for ions diffusion. The effect of different amount of PEDOT on the electrochemical properties of the PEDOT/paper is investigated. As expected, the prepared electrode exhibits high areal capacitance of 639 m F cm−2 and good conductivity of 78 S cm-1, remarkable stability under different bending angle conditions, which can be directly used as electrode for flexible and light-weight energy storage devices. It is believed that the method is useful to improve both electrical conductivity and capacitance of the PEDOT/paper, and further to optimize the electrochemical performance of the prepared material.

Ammonia Sensor Based on Vapor Phase Polymerized Polypyrrole

The detection of ammonia is an important issue for a lot of applications: leak detection in industry, agriculture, cooling systems, and medical diagnosis (breath biomarker for non-invasive diagnostic of renal disease). Among the possible sensing technologies, chemosensors based on conducting polymers show interesting characteristics. Polypyrrole (PPy) is well known for its sensitivity to ammonia. In the present work, PPy was synthesized by vapor phase polymerization (VPP) and treated with three different reductants. The ammonia sensing performance was investigated. The response of sodium sulfite Na2SO3 treated PPy was found to be much more pronounced when exposed to ammonia, it was twice as high as the grown PPy. A response of 15% at 500 ppb was obtained with an excellent selectivity towards ammonia compared to ethanol, acetone, and isopropanol. The role of chemical reduction of PPy in ammonia gas sensing was studied using different methods such as Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and ultra-violet, visible, near-infrared (UV–Vis–NIR) spectroscopy.

Elucidation of the Controversial Layer Growth Mechanism of Vapor Phase Polymerization in the Preparation of Conductive Poly(3,4‐ethylenedioxythiophene)‐SiO2 Hybrid Films

AbstractIn recent times, there have been debates to ascertain whether the growth mechanism in vapor phase polymerization is a top‐down or a bottom‐up process. The objective of the present study is to identify the formation mechanisms of the organic–inorganic hybrid film prepared in the gaseous phase on the basis of the practical importance of the hybridization of materials. To this end, poly(3,4‐ethylenedioxythiophene)‐SiO2 conductive hybrid films with different layered structures are successfully fabricated. The growth mechanism of the layered organic–inorganic conductive hybrid thin film is elucidated by investigating the variations in the morphological and chemical compositions of its surface. Additionally, a cross‐sectional analysis is performed using a scanning electron microscope‐energy dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy. The results indicate a “bottom‐up” growth mechanism, wherein the oxidant diffused through the recently formed layer, generating novel layers; this ultimately leads to formation of the organic–inorganic conductive hybrid film. Moreover, the optoelectronic and mechanical properties of the hybrid conductive films are precisely controlled by adjusting the order of incorporation of monomers in the process and the duration of polymerization of each monomer. Thus, this study achieves the fabrication of a mechanically robust and optically enhanced conductive hybrid film.

All-dry patterning method to fabricate hydrophilic/hydrophobic surface for fog harvesting

Inspired by natural creatures that live in the arid climate, fog harvesting can be an efficient approach to overcome freshwater scarcity. Fog harvesting ability of the creatures is mainly based on wettability differences of their surfaces. In this study, inspired by creatures that have hydrophilic regions surrounded by hydrophobic areas, a novel all-dry patterning method was applied to fabricate hydrophilic/hydrophobic patterned surfaces for fog harvesting. For this purpose, patterned surfaces were produced using plasma-enhanced chemical vapor deposition (PECVD) method with the help of a commercial magnet and iron powders. The idea behind the use of the magnetic field during PECVD deposition is to hold light iron particles on the substrate under the vacuum environment for masking substrate surface. For the first time, the magnetic field was used to fabricate patterned surfaces in vapor-phase polymerization. Ordinary glass slides were successfully transformed into hydrophilic/hydrophobic patterned glasses. The obtained results showed that the combination of hydrophobic and hydrophilic regions improved the fog harvesting performance.

Synthesis of Polypyrrole/V2O5 Composite Film on the Surface of Magnesium Using a Mild Vapor Phase Polymerization (VPP) Method for Corrosion Resistance

The vapor phase polymerization (VPP) method is a conventional strategy for synthesizing conducting polymers (CPs) on the surfaces of various materials. However, the current VPP method performed on a metal surface usually requires harsh reaction conditions, such as high temperature and low vacuum. In this paper, a polypyrrole (PPy) and vanadium pentoxide (V2O5) composite film was synthesized on the surface of Mg using a mild VPP method. Here, V2O5 was used as an oxidant, and it was found that the oxidation of pyrrole (Py) vapor on the surface of V2O5, which had been previously coated on the surface of Mg, could be performed at room temperature under normal atmospheric pressure. The formation of the PPy/V2O5 composite was verified by Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray (EDX) spectroscopy. A thermogravimetric analyzer (TGA) was used to study the thermal stability of the composite. Subsequent corrosion tests showed that the PPy/V2O5 composite film could slow down the corrosion of Mg in 3.5 wt% NaCl. It is expected that the mild VPP method may find great potential in the fields of synthesis of CPs and the corrosion protection of reactive metals.

A Simple Route to Prepare Polypyrrole-Coated Filter Papers via Vapor Phase Polymerization and Their Gas Sensing Application

Vapor phase polymerization has been used for the synthesis of polypyrrole-coated filter paper (PPy-FP) using a simple experimental setup. In addition, we have doped the polymer-coated filter papers...

Foldable and washable fully textile-based pressure sensor

Smart textiles have wide applications in various sensing systems since they have the advantage of maintaining the inherent properties of textile such as light weight, flexibility, comfort, and breathability. Therefore, textile-based pressure sensors, one of the smart textiles, have attracted considerable interest in wearable electronics and homecare systems. In this study, to construct a textile-based pressure sensor, a poly(3,4-ethylenedioxythiophene) (PEDOT) thin film was fabricated on a polyethylene terephthalate microfiber fabric by vapor phase polymerization with various concentrations of the oxidant, FeCl3. The PEDOT conductive textile showed a change in conductivity depending on the applied pressure. We confirmed the excellent washing and physical durability of the sensor from the stable electrical properties of the PEDOT conductive textile after washing and repeated folding tests. Furthermore, a fully textile-based pressure sensor was successfully fabricated using the highly durable PEDOT, which could simultaneously measure both static and dynamic pressures even during physical deformation, thus suggesting great potential in smart textiles, especially textile-based homecare systems.

Percolative polyurethane-polypyrrole-straw composites with enhanced dielectric constant and mechanical strength

Percolative polyurethane composites utilizing surface modified paddy straw particles as filler and exhibiting enhanced dielectric constant and tensile strength, low dissipation and reduced water absorption have been presented. A thin coating of Polypyrrole (PPy) conducting polymer over paddy straw (St) micro particles was accomplished via vapour phase polymerization. Composites were prepared by using a lab scale twin-screw compounder and injection moulding system to mimic the actual industrial processing conditions. At 30 phr, PPy coated particles filled composites exhibited 133 % and 26 % increment in dielectric constant (13.61, 1 KHz) and tensile strength (58.3 MPa) respectively with reduced water absorption by 51.3 % (264 h) at room temperature as compared to their counterparts filled with uncoated particles. The successful preparation of these lightweight composites with improved performance paves the way for low cost, sustainable and eco-friendly materials for high end applications including electronics and sensors.

Vaper Phase Polymerized PEDOT/Cellulose Paper Composite for Flexible Solid-State Supercapacitor

A flexible solid-state supercapacitor based on vapor phase polymerized (VPP) PEDOT into cellulose paper matrix (PEDOT/CP) was successfully fabricated. The PEDOT/CP composite material worked as both...

Multilayer assembly of electrospun/electrosprayed PVDF-based nanofibers and beads with enhanced piezoelectricity and high sensitivity

Flexible high-performance piezoelectric nanogenerators (PNG) that can convert mechanical energy into electricity are crucial for the development of self-powered wearable electronic devices. In this work, a 3D multilayer assembly of flexible organic polypyrrole (PPy) electrodes, electrospun poly(vinylidene fluoride) (PVDF) nanofibers and electrosprayed CsPbBr3@PVDF beads was proposed for a high-performance PNG, wherein two layers of CsPbBr3@PVDF beads were inserted between the top/bottom PPy electrodes and PVDF nanofibers layer, respectively. The PPy electrodes were fabricated via vapour phase polymerization of pyrrole monomers on the surface of the electrospun PVDF nanofibers with FeCl3 acted as an oxidant. As for the active piezoelectric layers, both the PVDF nanofibers and CsPbBr3@PVDF beads possessed high fractions of β crystalline phase, i.e., 83.5% and 94%, respectively, which helps to provide favorable polarization response. Besides, the introduction of the globular CsPbBr3@PVDF particles also facilitated the stress excitation to the piezoelectric layers, thus leading to enhanced output performance and high sensitivity. Piezoelectric results showed that the 3D multilayer NFMs based PNG exhibited a high open-circuit voltage of 10.3 V and a short-circuit current density of 1.29 μA/cm2, and could detect a weak pressure as low as 7.4 Pa. Furthermore, the PNG based fabrics also demonstrated excellent ability to harvest energy from the temperature fluctuations through pyroelectric effect. The structuration method of embedding globular particles into electrospun PVDF NFMs may open up the feasibility of fabricating high-output PNG.

Vapor-Phase Formation of a Hole-Transporting Thiophene Polymer Layer for Evaporated Perovskite Solar Cells.

Homogeneous layer formation on textured silicon substrates is essential for the fabrication of highly efficient monolithic perovskite silicon tandem solar cells. From all well-known techniques for the fabrication of perovskite solar cells (PSCs), the evaporation method offers the highest degree of freedom for layer-by-layer deposition independent of the substrate's roughness or texturing. Hole-transporting polymers with high hole mobility and structural stability have been used as effective hole-transporting materials (HTMs) of PSCs. However, the strong intermolecular interactions of the polymers do not allow for a layer formation via the evaporation method, which is a big challenge for the perovskite community. Herein, we first applied a hole-transporting terthiophene polymer (PTTh) as an HTM for evaporated PSCs via an in situ vapor-phase polymerization using iodine (I2) as a sublimable oxidative agent. PTTh showed high hole mobility of 1.2 × 10-3 cm2/(V s) and appropriate energy levels as HTM in PSCs (EHOMO = -5.3 eV and ELUMO = -3.3 eV). The PSCs with the in situ vapor-phase polymerized PTTh hole-transporting layer and a co-evaporated perovskite layer exhibited a photovoltaic conversion efficiency of 5.9%, as a proof of concept, and high cell stability over time. Additionally, the polymer layer could fully cover the pyramidal structure of textured silicon substrates and was identified as an effective hole-transporting material for perovskite silicon tandem solar cells by optical simulation.

Effects of interfacial modification for vapor phase polymerized PEDOT on glass substrate

Optically transparent and highly conductive poly(3,4-ethylenedioxythiophene) (PEDOT) thin films were grown through vapor phase polymerization on (3-Mercaptopropyl)trimethoxysilane functionalized 3,4-Ethylenedioxythiophene (MPTMS functionalized EDOT) grafted glass substrates. Compared to bare glass, the EDOT grafted surface led to enhancements in both electrical conductivity and adhesion of PEDOT thin films. A quinoid-rich structure with increased crystallinity and a further enhanced conductivity was induced by post-deposition sulfuric acid doping. X-ray diffraction showed different orientations of the PEDOT crystals grown on substrates with and without EDOT grafting. The highest conductivity of 2690 S/cm, with an average optical transmittance of 95.4 % in the visible range, was achieved when PEDOT was vapor phase polymerized on EDOT grafted substrates and doped with 98 % sulfuric acid. Photostability was tested using a xenon arc light source and characterized by attenuated total reflection Fourier-transform infrared spectroscopy, showing that photo-induced degradation is associated with a decrease in CC double bond content.

Synergistic functionalization of aligned silicon nanowires by Ag nanoparticles&PPy wrapping for improving gas-sensing response at high humidity level

Abstract In the field of disease diagnosis, there are few applications of gas sensors. But, gas sensors can specifically identify certain diseases. So, there is a great need for gas sensors capable of responding to trace amounts of special biomarker gases in high ambient humidity. The dual-modulated composite array of Ag NPs-modified PPy@SiNWs core-shell structures (Ag-PPy@SiNWs) are developed for sensitive response to a rarefied biomarker of NH3 at high ambient humidity. A repeated metal-assisted chemical etching (MACE) was first performed to fabricate a loose array of pristine SiNWs. Then Ag-PPy@SiNWs array one-step prepared via vapor phase polymerization (VPP) of Py on SiNWs with AgNO3 as oxidant. In the process, surface modification by Ag NPs is achieved in parallel to the PPy-shell formation during Py polymerization. PPy hetero-shell and Ag NPs contribute to NH3-sensing performance under high ambient humidity. Ag-PPy @ SiNWs can detect rare NH3 as low as 200 ppb at room temperature and 80% RH. Finally, the paper analyzes the sensing mechanism of Ag-PPy@SiNWs for NH3 under high humidity, especially the contribution induced by Ag NPs.

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.

Effects of ascorbic acid post-treatment on thermoelectric properties of poly (3, 4-ethylenedioxythiophene) thin films by a vapor phase polymerization

Thermoelectric (TE) material is a kind of energy conversion material, which can be used for power generation and refrigeration. Until now, traditional inorganic TE materials have shown high dimensionless thermoelectric figure of merit (<i>ZT</i>) values. But their expensive raw material and high processing cost, heavy metal pollution and poor processability limit their broad applications. Poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymers possess some excellent features, such as high electrical conductivity, low thermal conductivity, flexibility, low cost, abundance, and light weight. More and more attention has recently been paid to the TE properties of PEDOT polymers and PEDOT polymer based nanocomposites. Ascorbic acid (VC) is used as a reducing agent to tune the PEDOT-Tos-PPP film. The PEDOT-Tos-PPP films via VPP technique are treated with VC solutions with different concentrations. The TE properties of the films before and after being treated with VC at different concentrations are measured. The effect of concentration of VC aqueous solution on the thermoelectric properties and stabilities of the film are studied. The results indicate that the power factor of the film after being treated with 20% VC is 55.6 μW·m<sup>–1</sup>·K<sup>–2</sup>, which is 1.7 times as high as that of the pristine PEDOT-Tos-PPP film (34.4 μW·m<sup>–1</sup>·K<sup>–2</sup>). The maximum <i>ZT</i> value at room temperature is 0.032. After the VC treatment, the conductivity and Seebeck coefficient of the PEDOT film show unstable characteristics in the air, which is mainly due to the further oxidation of the neutral state on the PEDOT film surface in the air.

Deposition of an ultra-thin polyaniline coating on a TiO2 surface by vapor phase polymerization for electrochemical glucose sensing and photocatalytic degradation.

Here, we have synthesized an ultra-thin coating of polyaniline on a TiO2 nanoparticle surface (PANI–TiO2) using a simple vapor phase polymerization method. By this method, an ultra-thin layer of PANI is obtained selectively on the TiO2 surface. This ultra-thin coating exhibits the properties of both the parent materials due to the composite surface causing an effective synergistic effect. SEM, TEM, and EDX studies and elemental mapping confirmed the formation of ultra-thin films on the TiO2 surface. TGA, UV/Vis and XRD studies were also done for further characterization. The composite has been used as a biosensor for glucose detection by immobilization of the enzyme glucose oxidase (GOx). Cyclic voltammetry, electrochemical impedance spectroscopy and amperometry studies were performed for glucose sensing. The linear range was observed from 20 to 140 μM glucose concentration from the amperometric analysis. The LOD of the biosensor was found to be 5.33 μM. The composite has also been used for photocatalytic degradation of the cationic dye Rhodamine B (RB). The order of degradation efficiency of RB is found to be PANI < TiO2 < PANI–TiO2. The synergetic effect of PANI and TiO2 is the reason for the enhanced degradation efficiency of the composite PANI–TiO2.

Flexible ZnO/PANI/nonwoven nanocomposite based high-sensitive NH3 gas sensor via vapor phase polymerization method

A new synthetic method to flexible sensor towards NH3 with response magnitude as high as 4300% was based on vapor phase polymerization (VPP), where zinc oxide (ZnO) sheets were exposed to polyaniline (PANI) vapors on the flexible nonwoven fabric substrate. A possible brick wall masonry assembly structure of ZnO and PANI on the surface of nonwoven fabric was provided, which also possessed excellent mechanical flexibility and thermostability. The response value of flexible ZnO/PANI/nonwoven sensor increased from 5% to 4300% with the NH3 concentration varied over a wide range (0.5–10 ppm) at room temperature. Flexible and conductive ZnO/PANI/nonwoven composite material has good potential applications as NH3 gas sensor in environment monitoring components and wearable flexible devices.