Chemical Polymerization Method Research Articles

Zinc Oxide/Polypyrrole particle-decorated rod structure for NO2 detection at low temperature

In this study, Zinc oxide (ZnO) nanoparticles with a size of about 50 - 70 nm were green-synthesized using tea leaves and ZnO/Polypyrrole (ZnO/Ppy) nanocomposites were obtained by ultrasonic-assisted chemical polymerization method using pyrrole monomer and the nanoparticles. The characterization of the materials is conducted using several analytical techniques, including Field Emission Scanning Electron Microscopy (FESEM) and X-Ray Diffraction (XRD) and Ultraviolet visible spectrum (UV-Vis). The synthesized PPy material exhibits have a rod-shaped structure, diameter ranging from 100 to 200 nm. The ZnO/PPy nanocomposite system, consisting of PPy rods surrounded by ZnO particles. The gas sensing characteristics of the materials have also been investigated by measuring their sensitivity, response time, and stability to NO2 at low temperature and different humidity. Notably, the material exhibits considerable sensitivity to NO2 gas at low temperatures and the parameters related to response and recovery times are relatively rapid. Furthermore, a potential gas-sensing mechanism based on changes in the width of the depletion region is proposed.

Synthesis and characterisation of tamarind seed husk-derived carbon quantum dots incorporated polypyrrole nanosphere composite for energy storage applications

ABSTRACT In this study, the green synthesis of Tamarind Seed Husk-derived carbon quantum dots (TCQDs) by using a facile one-step hydrothermal technique and Tamarind Seed Husk-derived carbon quantum dots/Polypyrrole nanosphere composites (TCQDs/PPy-NS) was synthesised by using the facile in-situ chemical polymerisation method. These results suggest that the TCQDs/PPy-NS composite electrode is a promising electrode for high-energy storage applications. The TCQDs/PPy-NS composite offers an effective supercapacitor electrode material by blending the superior electrical conductivity of TCQDs with the increased pseudocapacitive capacity of polypyrrole nanospheres (PPy-NS). The TCQDs/PPy-NS composite exhibits a specific capacity (Csp) of 400 Fg−1 at a current density (CD) of 2 Ag−1, and a solid-state flexible symmetric supercapacitor (SSC) was developed using the TCQDs/PPy-NS composite to meet an excellent power density (PD) of 1008.19 Wkg−1 at an energy density (ED) of 31.02 Whkg−1 It also demonstrated excellent cycling stability with a capacity retention and coulombic efficiency of 84.57% and 98.06% after 4000 cycles at 2 Ag−1 respectively. This remarkable flexibility and stability make the TCQDs/PPy-NS SSC device highly suitable for applications in wearable electronics and flexible energy storage systems.

Preparation and Properties of Polyaniline/Hydroxypropyl Methylcellulose Composite Conductive Thin Films.

In this work, a chemical grafting polymerization method was employed to synthesize EHPMC-g-PANI self-supporting films. Polyaniline (PANI) was grafted onto hydroxypropyl methylcellulose (HPMC) modified with epichlorohydrin (EPHMC) to obtain an EHPMC-g-PANI aqueous dispersion, which was subsequently dried to form the self-supporting films. The introduction of HPMC, with its excellent film-forming ability and mechanical strength, successfully addressed the poor film-forming ability and mechanical properties intrinsic to PANI. Compared to in situ polymerized HPMC/PANI, the EHPMC-g-PANI exhibited significantly improved storage stability. Moreover, the fabricated EHPMC-g-PANI films displayed a more uniform and smoother morphology. The conductivity of all the films ranged from 10-2 to 10-1 S/cm, and their tensile strength reached up to 36.1 MPa. These results demonstrate that the prepared EHPMC-g-PANI holds promising potential for applications in various fields, including conductive paper, sensors, and conductive inks.

Eco-friendly engineering of micro composite-based hydroxyapatite bio crystal and polyaniline for high removal of OG dye from wastewater: Adsorption mechanism and RSM@BBD optimization

The presence of harmful substances such as dyes in water systems poses a direct threat to the quality of people's lives and other organisms living in the ecosystem. Orange G (OG) is considered a hazardous dye. The existing paper attempts to evaluate a low-cost adsorbent for the effective removal of OG dye. The developed adsorbent Polyaniline@Hydroxyapatite extracted from Cilus Gilberti fish Scale (PANI@FHAP) was elaborated through the application of the in situ chemical polymerization method to incorporate PANI on the surface of naturally extracted hydroxyapatite FHAP. The good synthesis of PANI@FHAP was evaluated through multiple techniques including X-ray diffraction (XRD), Scanning electron microscopy coupled with energy dispersive X-ray spectrometry (SEM/EDS), Fourier Transforms Infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) coupled with thermal differential analysis (DTA) analysis. The results reveal a highly ordered disposition of PANI chains on FHAP, resulting in a well-coated FHAP in the PANI matrix. Furthermore, the presence of functional groups on the surface of PANI such as amine (-NH2) and imine (=NH) groups would facilitate the removal of OG dye from contaminated water. The adsorption of OG onto PANI@FHAP was conducted in batch mode and optimized through response surface methodology coupled with box-Behnken design (RSM/BBD) to investigate the effect of time, adsorbent dose, and initial concentration. The outcomes proved that OG adsorption follows a quadratic model (R2 = 0.989). The kinetic study revealed that the adsorption of OG fits the pseudo-second-order model. On the other hand, the isotherm study declared that the Freundlich model is best suited to the description of OG adsorption. For thermodynamic study, the adsorption of OG is spontaneous in nature and exothermic. Furthermore, the regeneration-reusability study indicates that PANI@FHAP could be regenerated and reused up to five successive cycles. Based on the FTIR spectrum of PANI@FHAP after OG adsorption, the mechanism governing OG adsorption is predominantly driven by π-π interaction, electrostatic interaction, and hydrogen bonding interactions. The obtained results suppose that PANI@FHAP adsorbent can be a competitive material in large-scale applications.

Nitrogen-doped carbon nano-onions/polypyrrole nanocomposite based low-cost flexible sensor for room temperature ammonia detection

One of the frontier research areas in the field of gas sensing is high-performance room temperature-based novel sensing materials, and new family of low-cost and eco-friendly carbon nanomaterials with a unique structure has attracted significant attention. In this work, we propose a novel low-cost flexible room temperature ammonia gas sensor based on nitrogen-doped carbon nano-onions/polypyrrole (NCNO-PPy) composite material mounted low-cost membrane substrate was synthesized by combining hydrothermal and in-situ chemical polymerization methods. The proposed flexible sensor revealed high sensing performance when employed as the sensing material for ammonia detection at room temperature. The NCNO-PPy ammonia sensor exhibited 17.32% response for 100 ppm ammonia concentration with a low response time of 26 s. The NCNO-PPy based flexible sensor displays high selectivity, good repeatability, and long-term durability with 1 ppm as the lower detection limit. The proposed flexible sensor also demonstrated remarkable mechanical robustness under extreme bending conditions, i.e., up to 90° bending angle and 500 bending cycles. This enhanced sensing performance can be related to the potential bonding and synergistic interaction between nitrogen-doped CNOs and PPy, the formation of defects from nitrogen doping, and the presence of high reactive sites on the surface of NCNO-PPy composites. Additionally, the computational study was performed on optimized NCNO-PPy nanocomposite for both with and without NH3 interaction. A deeper understanding of the sensing phenomena was proposed by the computation of several electronic characteristics, such as band gap, electron affinity, and ionization potential, for the optimized composite.

A cellulose derived nanofibrous nitrogen-doped carbon/TiO2/SnO2/carbon composite anodic material for lithium storage

SnO2 with high theoretical specific capacity is regarded as a desirable anodic material for lithium storage. However, the serious volume variation during discharge/charge cycling and poor conductivity significantly constrain the electrochemical performance. Herein, nanofibrous nitrogen-doped carbon (NC)/TiO2/SnO2/carbon composite was fabricated through layer-by-layer assembly of SnO2 and TiO2-gel layers alternately using cellulosic filter paper as the structural scaffold, followed by deposition of polypyrrole on the surface by chemical polymerization method, and subsequent calcination of the as-obtained matter in inert atmosphere. The achieved composite possesses a typical three-dimensional fibrous porous network structure inherited from the cellulosic substrate, and complete NC nanolayer coating on each nanofiber by adjusting the amount of pyrrole, which can alleviate the volume change and increase the conductivity of SnO2. Furthermore, the interlaced TiO2 multilayer can enhance the cycling stability during cycling, as well as facilitate the lithium-ion transfer through abundant interface. The optimal NC/TiO2/SnO2/carbon composite delivers an initial discharge capacity of 1492.6 mAh g−1 at a current density of 100 mA g−1, and retains a reversible capacity of 680.8 mAh g−1 after 200 discharge/charge cycles. This work provides an efficient strategy for design and construction of metal-oxides/carbon composite anodic materials with hierarchical microstructure that hold great potential in lithium storage.

Fabrication of Zigzag Parylene Nanofibers in Liquid Crystals with Electric Field-Induced Defect Structures.

Liquid crystals (LCs) have been adopted to induce tunable physical properties that dynamically originated from their unique intrinsic properties responding to external stimuli, such as surface anchoring condition and applied electric field, which enables them to be the template for aligning functional guest materials. We fabricate the fiber array from the electrically modulated (in-plain) nematic LC template using the chemical vapor polymerization (CVP) method. Under an electric field, an induced defect structure with a winding number of -1/2 contains a periodic zigzag disclination line. It is known that LC defect structures can trap the guest materials, such as particles and chemicals. However, the resulting fibers grow along the LC directors, not trapped in the defects. To show the versatility of our platform, nanofibers are fabricated on patterned electrodes representing the alphabets 'CVP.' In addition, the semifluorinated moieties are added to fibers to provide a hydrophobic surface. The resultant orientation-controlled fibers will be used in controllable smart surfaces that can be used in sensors, electronics, photonics, and biomimetic surfaces.

Distinguishable photocatalytic activity of nano polyaniline with quantum dots metal oxide as photocatalysts for photodegradation of Dianix blue dye and different industrial pollutants

Nanopolyaniline (PAN) polymers have recently been under active investigation as promising photocatalysts. In this work, a simple modified sol–gel method is used to make nano PAN polymers, and a chemical polymerization method is used to make nano polyaniline titanium dioxide quantum dots (PAN-TiQD) polymers as an active photocatalyst during the photodegradation of Dianix blue dye as an organic pollutant under xenon light. The traditional colloidal sol–gel method and the microwave-assisted hydrothermal method were used to make TiQD, which was then mixed with nanoPAN to make PAN-5 % TiQD (W/W) nanocomposites. Characterizations like XRD, FTIR, UV and visible diffuse reflectance spectra, TGA, surface area, EDX, and TEM were used to characterize the nanoPAN and PAN-TiQD that were made. Also, the photocatalytic activity of all synthesized polymers was investigated by the photodegradation process of Dianix blue dye as an organic hazardous pollutant in aqueous medium using a xenon photoreactor with an initial power of 75 W/Cm2. The effects of irradiation time and photocatalyst type on the photodegradation process efficiency of Dianix blue dye were examined. After 3 h of photodegradation processes, the photodegradation efficiency of PAN-TiQD reached 69 % compared to 36 % of nanoPAN due to the fact that it contains 5 % TiQD as a highly active catalyst, which reached 91 %. As an added value for this study, a significant contribution is the examination of eight hazardous industrial wastewater samples, which were assessed under direct sunlight and were in accordance with the KSA environmental permissible limit of 1000 ppm.Finally, the recycling processes in the presence of all synthesized catalysts were investigated and evaluated six times. The photodegradation rate of the recycling processes of Dianix blue dye was highly decreased in the presence of nano PAN than PAN-TiQD, while it had a low decreasing percentage in the case of TiQD. The recycling process using sunlight for industrial pollution samples was investigated at one of the KSA textile plants by using six synthetic catalysts and assessing COD and TOC values.

Synthesis of water-soluble nitrogen doped carbon quantum dots-polypyrrole nanocomposite via in-situ polymerization for high performance supercapacitor application

In this work, water-soluble nitrogen doped carbon quantum dots (NCQDs) were synthesized via a hydrothermal approach, and nitrogen doped carbon quantum dots-polypyrrole nanocomposites (NCQDs/PPy) were synthesized using In-Situ chemical polymerization methods. The synthesized pure NCQDs, PPy, and NCQDs/PPy nanocomposites are characterized with help of X-ray diffractometry (XRD), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM), Ultraviolet-Visible (UV–Vis) spectroscopy, and Raman spectroscopy techniques to study their chemical changes, structural phase, morphology, and optical properties. The electrochemical performance is investigated through a two-electrode system, and the NCQDs/PPy-2 nanocomposite shows a high specific capacitance (Csp) of 750 Fg−1 at a current density (CD) of 1 Ag−1 with a wide operating potential window from −0.8 V to 0.8 V. In addition, the fabricated symmetrical device shows an energy density (ED) of 43.47 Whkg−1 and a high-power density (PD) of 3129.84 Wkg−1. Besides, the NCQDs/PPy-2 shows a higher cycle life span with 77.82 % of capacitance retention and 97.04 % of coulombic efficiency even after 8000 charging and discharging cycles. These findings demonstrate that NCQDs/PPy-2 nanocomposite material is a highly prominent electrode material for supercapacitor applications.

MXene/PANI composite fiber-based asymmetric supercapacitors for self-powered energy storage system

Fiber-shaped supercapacitors (FSSCs) have attracted tremendous attention for their various potential applications in portable and wearable electronics. However, the low energy density of FSSCs hinders their wide applications in wearable electronics. Herein, we develop an in-situ chemical polymerization method to construct MXene/polyaniline-based asymmetric FSSCs, which delivers an excellent electrochemical performance, including excellent rate capability, high area specific capacitance (510 mF cm−2) and energy density (15.71 μWh cm−2). This work provides a new strategy for fabricating high-performance flexible supercapacitors and paves the way for the development of wearable energy storage devices.

ELECTRICAL PROPERTIES ON COPOLYESTER INCORPORATED IN A POLYMER NANOCOMPOSITE MATRIX - A STUDY

This study aims at the application of the prepared Polymer Nanocomposite in the field of solid-state optoelectronic devices. Polymer Nanocomposite was prepared by incorporating iron nanoparticles, synthesized random Copolyester (BCTP), and Polypyrrole by Insitu chemical polymerization method. The application of the synthesized random Copolyester with wide biological activity due to bis chalcone moiety can also be extended to the optoelectronics field. The Copolyester (BCTP) was subjected to spectral analysis such as Fourier Transform Infrared Spectroscopy (FTIR) to confirm the chemical structural orientation. The Iron nanoparticles, Polypyrrole, and polymer nanocomposite were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and powder X-ray Diffraction (PXRD). The FTIR spectroscopy confirms the formation of polymer nanocomposite by the prominent shift in stretching frequency from the starting materials taken. Powder X-ray Diffraction was used to determine the Iron Nanoparticles’ average crystallite size. The structural morphology of iron nanoparticles, Polypyrrole, and polymer nanocomposite were identified by Scanning electron Microscopy. The SEM images gave the view of Iron nanoparticles, Polypyrrole was seated in the Polymer matrix. The specific capacitance for the newly synthesized Polymer Nanocomposite was found to be 58.88 F/g by Cyclic Voltammetric analysis. The electrochemical behavior of the random copolyester (BCPT), Iron nanoparticles, Polypyrrole, and polymer nanocomposite was carried out by Impedance analysis. This confirms the Polymer Nanocomposites were conducting nature with good ionic conductance of 6.89 × 10-5 S cm-1.

Synthesis, Surface Morphology, Gas Sensor, DSC Technique and Third-Order Behavior of Conducting Polymer.

The compound polyaniline (Poly-ANI) with different concentrations of (H2SO4) sulfuric acid has been synthesized by the chemical polymerization method. The prepared compounds have been characterized using number of techniques including FTIR, FE-SEM, EDS and DSC. Additionally, UV-Vis spectroscopy employed for studying the linear optical properties of polymer with different acid concentrations. Third order optical nonlinearity was characterized using Z-scan at 532nm. The results showed that the nonlinear refractive index has a negative sign. It was observed that the nonlinear refractive index changes in different ratios of H2SO4. The high value of nonlinear refractive index ([Formula: see text]) obtained along Z-axis is [Formula: see text] cm2/W, and the corresponding [Formula: see text] is 21.5 × 10-5 esu. Also, the Poly-ANI film shows the response to NH3 gas sensing in the range 20ppm-250ppm and can be used for NH3 sensing application.

Chemical, Electrochemical and Plasma Polymerization of Pyrrole-Aniline Copolymers and Their Characterization

Pyrrole-aniline copolymers (poly(Py-co-Ani)) were synthesized using both three chemical, electrochemical and plasma polymerization methods. Comparison of the copolymers synthesized with three methods was investigated. Fourier transform infrared spectroscopy (FT-IR), thermogravymetric analysis (TG-DTA), scanning electron microscopy (SEM) and conductivity results confirmed that the poly(Py-co-Ani) copolymers were successfully obtained in all cases with some differences according to synthesis methods. It was found that plasma method enhanced the thermal stability of the poly(Py-co-Ani) copolymer. The first thermal decomposition temperatures of chemically, electrochemically and plasma polymerized copolymers are 210, 190 and 250 °C, respectively. However, the conductivity value of plasma polymerized copolymer (1,97x10-4 S.cm-1) is lower than that of chemical (4,40x10-4 S.cm-1) and electrochemical (3,14x10-4 S.cm-1) synthesized copolymers. According to findings chemical and electrochemical polymerization methods provides nearly the same properties to the copolymers. Plasma polymerization method provides better thermal properties to copolymer. The both three methods can be used for preparing the pyrrole and aniline copolymers.

Enhanced luminescence and electrical conductivity of polymer ultrathin films doped with TiO2 nanoparticles

The chemical polymerization method was used to prepare nanocomposite materials of polyaniline (PANi) and Titanium dioxide (TiO2) nanoparticles. Ultrathin films were deposited by using the Langmuir Blodgett (LB) Technique. Surface Pressure vs mean molecular area isotherms of nanocomposite materials showed an increase in maximum attained surface pressure with variation in nanoparticle doping concentration. Photoluminescence (PL) spectra were taken for LB multilayers deposited on a quartz substrate, an increase in the intensity of PL peaks with increasing doping concentration of TiO2 nanoparticles. The topography of LB monolayer film under atomic force microscopy (AFM) revealed that films were uniformly and densely deposited on the substrate. Phase imaging ensured the presence of nanoparticles in the polymer matrix. Conductive atomic force microscopy (C-AFM) was used to investigate the local electrical properties of nanocomposite LB films. Current-voltage characteristics showed variation in current with changing doping concentrations of TiO2 nanocomposite in PANi matrix. The work presents new insights in analyzing uniformly deposited ultrathin films of the composites which can be probed by C-AFM to reveal local electric properties by understanding topography-current correlation at the nanoscale. The conductive data analysis could be useful for understanding the current flow through the nanostructure surface.

Preparation of waste face masks modified with MnO2/poly(m-phenylenediamine) as a novel adsorbent for hexavalent chromium removal: Comprehensive batch and column study

Single-use surgical face masks (SFM) have become one of the most used personal protective equipment (PPE) for preventing the transmission of diseases, especially COVID-19. However, the environment is being threatened by the huge amount of plastic waste generated by this material. In this study, a novel environmentally-friendly in-situ-surface polymerization method was employed to modify the surface of SFM with m-phenylenediamine (mPDA) for removing hexavalent chromium. The synthesized adsorbent was characterized by Field Emission-Scanning Electron Microscopy (FESEM) and Fourier Transform Infrared Spectroscopy (FTIR). The investigations showed that the polymer and oxidant solution can be reused for several cycles, which was not possible in the conventional chemical polymerization method with ammonium persulfate (APS). The influence of various variables on the adsorption process was assessed and the optimum results was reported (adsorbent dosage: 3 g L−1, contact time: 60 min, pH: 2). The modeling investigations demonstrated that the process is followed by pseudo-second-order kinetic and University of Tehran (UT) isotherm model's assumptions, respectively. The obtained thermodynamic parameters at the investigated temperatures revealed the spontaneity and endothermic nature of Cr(VI) adsorption on the modified adsorbent. The column study was conducted and the impact of the flow rate and the feed concentration of Cr(VI) were evaluated. The experimental findings were analyzed using the Thomas model to discover how the concentration changes over time in the column operation. It was revealed that when the flow rate rose, the service volume declined.

Polypyrrole-coated expanded graphite-based phase change materials for photothermal energy storage

Pristine organic phase change materials (PCMs) suffer from liquid leakage and weak solar absorption in solar energy utilization. To address these deficiencies, we prepared polypyrrole (PPy)-coated expanded graphite (EG)-based composite PCMs for photothermal conversion and storage through chemical polymerization and physical infiltration methods. As dual high-efficiency photonic harvesters and molecular heaters, the synergistic integration of PPy and EG significantly boosts the photothermal conversion and storage capability of polyethylene glycol (PEG). The melting enthalpy and solidification enthalpy of PEG@EG/PPy composite PCMs are 148.3 and 141.5 J/g, respectively. Additionally, PEG@EG/PPy composite PCMs also exhibit superior shape stability and latent heat storage retention after undergoing 200 melting-freezing cycles. This convenient strategy sheds light on the large-scale development of high-performance carbon-based photothermal composite PCMs, showing great potential in solar energy utilization.

Preparation and characterization of chemically and electrochemically synthesized 3,4-ethylenedioxy pyrrole/pyrrole (EDOP/Py) copolymers

Abstract In this study, 3,4-ethylenedioxypyrrole (EDOP) and pyrrole (Py) copolymers were prepared by chemical and electrochemical polymerization methods. The properties of the polymers obtained by both methods were compared. Chemical synthesis of copolymers was carried out with ferric chloride (FeCl3) in the acetonitrile (ACN) environment. The electrochemical synthesis was carried out with lithium perchlorate (LiClO4) electrolyte and suitable oxidation potential range in ACN solution. The properties of polypyrrole (PPy) copolymers were performed with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and conductivity measurements. Depending on the polymerization method and pyrrole amount in copolymer, thermal stability, conductivity and surface morphology were varied.

Structure and electrochemical properties of magnetite and polypyrrole nanocomposites formed by pyrrole oxidation with magnetite nanoparticles

Nanocomposite of magnetic Fe3O4 nanoparticles and polypyrrole was prepared under sonication by a new chemical polymerization method during which Fe3O4 nanoparticles acted both as a pyrrole oxidant and as a component in the composite material. Synthesis of this nanocomposite was carried out in aqueous solution acidified to pH 2, a prerequisite for the formation of these types of material and to facilitate pyrrole oxidation by Fe3O4 nanoparticles. In this way, two kind of materials were produced: Fe3O4/PPy nanocomposite in which magnetite nanoparticles were dispersed in PPy matrix and Fe3O4-aggregates@PPy nanocomposite that exhibits structure in which aggregates of magnetite nanoparticles are surrounded by a layer of polymeric phase. In the latter case, the polymerization process took place in the presence of a surfactant. These nanocomposites were characterized by electron microscopy techniques, IR spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and thermogravimetry. Particular attention was focused on the study of the electrochemical properties of the formed composites. The composite of Fe3O4 and PPy exhibits reversible electrochemical behaviour upon oxidation. The electrode process of the polymeric component oxidation in organic solvents such as acetonitrile and dichloromethane is very similar to the process in an aqueous solution.

Room temperature sensing of primary alcohols via polyaniline/zirconium disulphide

Among the primary alcohols, ethanol is referred to as a heavy chemical due to its many applications in a variety of industries. Detection of primary alcohols can be deployed as a non-invasive method in medical diagnosis and safety measures in food processing companies. Zirconium disulphide is a novel 2D layered material with exotic features when in mono or few layers, which include fast electron transport, high carrier mobility and sizeable band gap. ZrS2 and PANI were fabricated using liquid exfoliation and chemical polymerization methods respectively. Functionalization of the conducting polyaniline with ZrS2 was done using facile sonication process. The sensor showed good sensitivities (43%, 58% and 104%) which were estimated from slopes of the linear fitted plots with fast response-recovery times of 8 s and 27 s (111 ppm); 12 s and 130 s (77 ppm); and 58 s and 88 s (58 ppm). Good reproducibility at three repeated measurements (111 ppm, 77 ppm and 58 ppm) was also observed for methanol, ethanol, and isopropanol vapours respectively. Meanwhile, the sensor displayed more linearity and sensitivity towards isopropanol compared to methanol and ethanol. The sensor showed good performance even at RH values close to 100% making it a potential alcohol breath analyser.

Low-temperature resin embedding of the whole brain for various precise structures dissection

Resin embedding combined with ultra-thin sectioning has been widely used in microscopic and electron imaging to acquire precise structural information of biological tissues. However, the existing embedding method was detrimental to quenchable fluorescent signals of precise structures and pH-insensitive fluorescent dyes. Here, we developed a low-temperature chemical polymerization method named HM20-T to maintain weak signals of various precise structures and to decrease background fluorescence. The fluorescence preservation ratio of green fluorescent protein (GFP) tagged presynaptic elements and tdTomato labeled axons doubled. The HM20-T method was suitable for a variety of fluorescent dyes, such as DyLight 488 conjugated Lycopersicon esculentum lectin. Moreover, the brains also retained immunoreactivity after embedding. In summary, the HM20-T method was suitable for the characterization of multi-color labeled precise structures, which would contribute to the acquisition of complete morphology of various biological tissues and to the investigation of composition and circuit connection in the whole brain.