Oriental Lacquer: A Natural Polymer

Urushiol-Based Coating with High Surface Hydrophilicity for Easy-Cleaning of Oil Pollutants

Urushiol is recognized as a sustainable coating material with superior properties; however, it faces significant challenges in applications such as petrochemicals and marine engineering due to surface oil contamination. This study aimed to enhance the cleanability of urushiol-based coatings through hydrophilic modification. Polyethylene glycol monooleate (PEGMO) was identified as an appropriate hydrophilic macromonomer and utilized as a modifier to develop a novel urushiol-based coating, termed P(U-PEGMO), via thermal curing. The results indicated that copolymerization occurred between urushiol and PEGMO during the curing process, forming a stable urushiol copolymer with favorable compatibility. The incorporation of PEGMO greatly improved the surface hydrophilicity of the coatings, as evidenced by a reduction in the water contact angle to below 30° when the modifier content reached 30% or higher, demonstrating a high degree of surface hydrophilicity. This enhanced property imparted the modified coating with underwater superoleophobicity and reduced oil adhesion, thereby facilitating the removal of oil. The cleaning performance was evaluated using a simple water rinsing method, after which, less than 2.5 wt% of oil residues remained on the surface of the modified coating. The high hydrophilicity is considered responsible for the coating's easy-cleaning capability. In addition, the modified coatings exhibited improved flexibility and impact resistance, albeit with a slight decrease in hardness.

Development of Novel Cardanol-Derived Reactive Dispersing Agents for Bio-Based Anionic-Nonionic Waterborne Polyurethane

This study successfully developed a bio-based, photocurable, anionic-nonionic dual-functional chain extender, and sulfonated cardanol-based polyethylene glycol (SCP), derived from renewable resources-cardanol and polyethylene glycol-for application in waterborne polyurethane dispersions (WPUDs). Utilizing SCP as a chain extender, WPUDs were prepared through a typical acetone process with poly(butylene adipate) (PBA), isophorone diisocyanate (IPDI), and ethylene diamine (EDA) at a constant NCO/OH ratio of 1:1. This research focused on the effects of polyethylene glycol molecular weight and SCP dosage on the particle size, stability, and film-forming properties of the WPUD. Optimal dispersion stability and film-forming performance were achieved with a polyethylene glycol molecular weight of 1500 and a PBA to SCP molar ratio of 4:1, yielding a particle size of 0.326 ± 0.010 μm and excellent storage stability over six months. The resulting WPU coatings exhibited a tensile strength of 11.4 MPa, which increased to 16.8 MPa after UV irradiation owing to the formation of a semi-interpenetrating network via the photopolymerization of cardanol's unsaturated side chains. UV cross-linking also enhanced water resistance, reducing the water absorption rate (WAR) from 18.68% to 4.21% and the water vapor transmission rate (WVTR) from 6.59 × 10-5 g·m⁻¹·Pa⁻¹·d⁻¹ to 2.26 × 10⁻⁵ g·m⁻¹·Pa⁻¹·d⁻¹, while also improving thermal stability. These findings demonstrate that SCP offers a sustainable and effective solution for developing high-performance WPU coatings.

Polysaccharide metabolism in Anacardiaceae (Asian lacquer) cross-linked polymers elucidated using in situ trimethylsilylation pyrolysis-gas chromatography-mass spectrometry

Carbohydrates from polysaccharides in natural thermoset Anacardiaceae polymers of Gluta usitata, Toxicodendron succedaneum and Toxicodendron vernicifluum were identified using pyrolysis-gas chromatography-mass spectrometry with in situ trimethylsilylation. Pyrolysates resulting from the pyrolytic intermolecular chain scission of the polysaccharides were used to elucidate monomeric units. Polysaccharides, dispersed in the phenolic lacasse catalysed cross-linked macromolecules, showed to be metabolised through various catabolic and anabolic routes. Galactose functionalities, abundantly present in the polysaccharides were determined to be enzymatically converted to glucose-6-phosphate, followed by conversion via glycolysis and pentose phosphate pathways. Determination of specific routes of carbohydrate modification via glycolysis and pentose phosphate pathways facilitated differentiating G. usitata, T. succedaneum and T. vernicifluum polymers, based on the carbohydrate content. It was also found that uronic type acids, present as end groups of the branched polysaccharide structure, were biochemically converted to aldonic acids. Following the pentose phosphate and glycolysis routes, carbohydrates in G. usitata and T. vernicifluum polymers showed to be further modified via shikimate and cinnamate pathways to produce phenylpropanoid compounds. Parent molecules and pyrolysis products thereof were verified using analytical standards of high purity. The mass spectra and Kovats retention indices were compiled in an AMDIS library, which can be made available on request.

Quantitative Detection of Thitsiol and Urushiol as Markers from the Gluta usitata Lacquer Tree Using HPLC

Lacquer sap has been traditionally used in coatings and artwork. Suitable types of lacquer are required to preserve and restore artifacts. Recently, unsuitable cashew nut shell liquid (CNSL) has often been mixed with lacquer sap, so it is necessary to identify the characteristics of lacquer sap by the production area. However, research is still focused on urushiol and laccol. In this study, Myanmarese lacquer sap collected from Gluta usitata, which contains thitsiol as the main component, was analyzed by HPLC to quantify thitsiol using the standards 3-(10-phenyldecyl) benzene-1,2-diol (thitsiol 16) and 3-(8Z,11Z-pentadecadienyl)-benzenediol (urushiol 15:2) as markers, and calibration curves were plotted. The coefficients of determination (R2) for thitsiol 16 and urushiol 15:2 were 0.9985 and 0.9983, respectively. In addition, a blind test was conducted to confirm that accurate quantitative analysis was possible even when Myanmarese lacquer was mixed with lacquer from another production area, which contained urushiol as the main component, and CNSL, which contained cardol, a completely different catechol. Quantitative analysis of thitsiol 16 and urushiol 15:2 in Myanmarese lacquer using HPLC can be used to evaluate the quality of lacquer sap and for more sophisticated activities such as restoration by classifying differences in lacquer sap by the production area.

Glancing at the birth of a galaxy of scientists from Rikō Majima

Rikō Majima published seven papers in this journal, and seeing these papers and their surrounding contexts allows us to glance at the birth of a galaxy of scientists.

Zn2+ @Polyvinylpyrrolidone and Urushiol Preparation of Nanofibrous Membranes and Their Synergistic Effect

In this study, lacquer is gathered from a lacquer tree and rotary evaporation is used to remove impurities to obtain urushiol. Next, 10 mL of anhydrous ethanol serves as the solvent for blending polyvinylpyrrolidone (PVP) at a specified content (0.7 g and 0.2-0.7 g urushiol) to form an electrospinning solution. Electrospinning is carried out with a voltage of 18 kV to prepare PVP/urushiol nanofibrous membranes. At a ratio of 7/4, the PVP/urushiol nanofibrous membranes are not eroded in 98% sulfuric acid and these membranes also demonstrate a 50-60% antibacterial effect against Staphylococcus aureus and Escherichia coli. Moreover, the antibacterial effect can be boosted to 98% with the incorporation of zinc ions. The results indicate that anhydrous ethanol can remove the sensitization of urushiol from PVP/urushiol membranes. Furthermore, animal test results indicate that when rats are in contact with PVP/urushiol anhydrous ethanol for 48 h, their skins are free from dark brown skin allergy. The presence of PVP eliminates the sensitization of urushiol, and the nanofibrous membranes demonstrate low toxicity. Hence, urushiol is the only natural material that enables PVP to withstand 98% sulfuric acid as well as acquire hydrolyzability, thereby qualify PVP as a medical material.

Synthesis and Study of a Metal-Organic Framework-based Sulfite Fluorescence Sensor Modified with Urushiol

Sulfites can pollute the environment and pose a great risk to human health in daily life, so there is an urgent need to develop efficient and lightweight sulfite detection materials. In this study, metal-organic framework-5-NH2/urushiol/PVP nanofiber composite films were prepared by an electrospinning technique for the fluorescence detection of sulfites. The results showed that the composite film could resist sulfuric acid corrosion at a concentration of 80% and inactivate Escherichia coli and Staphylococcus aureus at a concentration of 99%, and its maximum tensile strength was increased from the initial 2.753 to 4.145 N. The composite film was sensitive and specific for the fluorescence detection of sulfite.

Urushiol-Based Benzoxazine Containing Sulfobetaine Groups for Sustainable Marine Antifouling Applications

Benzoxazine resins are new thermosetting resins with excellent thermal stability, mechanical properties, and a flexible molecular design, demonstrating promise for applications in marine antifouling coatings. However, designing a multifunctional green benzoxazine resin-derived antifouling coating that combines resistance to biological protein adhesion, a high antibacterial rate, and low algal adhesion is still challenging. In this study, a high-performance coating with a low environmental impact was synthesized using urushiol-based benzoxazine containing tertiary amines as the precursor, and a sulfobetaine moiety into the benzoxazine group was introduced. This sulfobetaine-functionalized urushiol-based polybenzoxazine coating (poly(U-ea/sb)) was capable of clearly killing marine biofouling bacteria adhered to the coating surface and significantly resisting protein attachment. poly(U-ea/sb) exhibited an antibacterial rate of 99.99% against common Gram negative bacteria (e.g., Escherichia coli and Vibrio alginolyticus) and Gram positive bacteria (e.g., Staphylococcus aureus and Bacillus sp.), with >99% its algal inhibition activity, and it effectively prevented microbial adherence. Here, a dual-function crosslinkable zwitterionic polymer, which used an "offensive-defensive" tactic to improve the antifouling characteristics of the coating was presented. This simple, economic, and feasible strategy provides new ideas for the development of green marine antifouling coating materials with excellent performance.

Chitosan-Urushiol nanofiber membrane with enhanced acid resistance and broad-spectrum antibacterial activity

Due to the large specific surface area and rich pore structure, chitosan nanofiber membrane has many advantages over conventional gel-like or film-like products. However, the poor stability in acidic solutions and relatively weak antibacterial activity against Gram-negative bacteria severely restrict its use in many industries. Here, we present a chitosan-urushiol composite nanofiber membrane prepared by electrospinning. Chemical and morphology characterization revealed that the formation of chitosan-urushiol composite involved the Schiff base reaction between catechol and amine groups and the self-polymerization of urushiol. The unique crosslinked structure and multiple antibacterial mechanisms endowed the chitosan-urushiol membrane with outstanding acid resistance and antibacterial performance. After immersion in HCl solution at pH 1, the membrane maintained its intact appearance and satisfactory mechanical strength. In addition to its good antibacterial performance against Gram-positive Staphylococcus aureus (S. aureus), the chitosan-urushiol membrane exhibited synergistic antibacterial activity against Gram-negative Escherichia coli (E. coli) that far exceeded that of neat chitosan membrane and urushiol. Moreover, cytotoxicity and hemolysis assays revealed that the composite membrane had good biocompatibility similar to that of neat chitosan. In short, this work provides a convenient, safe, and environmentally friendly method to simultaneously enhance the acid resistance and broad-spectrum antibacterial activity of chitosan nanofiber membranes.

Kinetics of thermal degradation of raw lacquer enhanced by formaldehyde urea prepolymer

In this study, formaldehyde-urea prepolymer (FUP) were synthesized, which were used to modify the raw lacquer (RL) and this composition named LF, while the basic properties of the RL were tested. Thermal gravimetric (TG) analysis and scanning electron microscopy (SEM) were used to analyze the degradative characteristics and the surface morphology of RL before and after modification. The result indicated that FUP can significantly improve the performance of RL. The drying time of the LF is significantly shortened, the gloss, the pencil hardness, and the impact performance are significantly enhanced at the same time. TG analysis and thermal decomposition kinetics analysis illustrated that the thermal stability and the activation energy of LF2 were stronger than that of RL. In addition, SEM analysis illustrated that the surface smoothness of RL were also improved.

Challenges in Elucidating the Free Energy Scheme of the Laccase Catalyzed Reduction of Oxygen

Artificial redox catalysts are typically limited by unfavorable scaling relations of reaction intermediates leading to a significant overpotential in multi-electron redox reactions such as for example the oxygen reduction reaction (ORR). The multicopper oxidase laccase is able to catalyze the ORR in nature. In particular the high-potential variants show a remarkably low overpotential for the ORR and apparently do not suffer from such unfavorable scaling relations. Although laccases are intensively studied, it is presently unknown why the overpotential for ORR is so low and a clear description regarding the thermodynamics of the catalytic cycle and the underlying design principles is lacking. In order to understand the laccase catalyzed ORR from an electrochemical perspective, elucidation of the free energy scheme would be of high value. This article reviews the energetics of the proposed laccase catalyzed ORR mechanisms based on experimental and computational studies. However, there are still remaining challenges to overcome to elucidate the free energy scheme of laccase. Obtaining thermodynamic data on intermediates is hard or even impossible with analytical techniques. On the other hand, several computational studies have been performed with significantly different parameters and conditions, thus making a direct comparison difficult. For these reasons, a consensus on a clear free energy scheme is still lacking. We anticipate that ultimately conquering these challenges will result in a better understanding of laccase catalyzed ORR and will allow for the design of low overpotential redox catalysts.

Urushiol modified epoxy acrylate as UV spray painting oriental lacquer ink

As a natural "water-based" polymer composite material, oriental lacquer is often referred to as the "king of coatings" and is used as a coating in the defense industry, chemical industry, petroleum industry, metallurgy and mining industry, textile painting and dyeing industry, pharmaceutical industry, as well as the protection of ancient buildings and cultural relics. However, the development of modern industrialization is greatly hindered by the high viscosity of oriental lacquer, the difficulty of spraying, the long drying cycle, and the seriousness of allergenicity. Herein, based on the principle of oriental lacquer and the characteristics of prepolymer in ink, we developed a new prepolymer for modulating UV oriental lacquer ink and explored the feasibility of using it as a raw material for UV spray painting. In this study, lacquer phenol was extracted from oriental lacquer and modified with epoxy acrylate by a simple mechanical compounding method to obtain lacquer epoxy acrylate. Moreover, the UV spray painting oriental lacquer ink was also prepared by using it as the main film-forming substance. The orthogonal experiment method was used to optimize the best formulation of UV spray painting oriental lacquer ink by using nozzle passability, viscosity and curing time as test indexes. Meanwhile, the film properties of UV spray painting oriental lacquer inks were also evaluated. The test results show that the UV spray painting oriental lacquer ink prepared with urushiol epoxy acrylate has better dispersion, excellent paint film performance, and solves the problem that oriental lacquer cannot be printed. This present work shows that urushiol epoxy acrylate as a new type of prepolymer has broad application prospects in the actual preparation of UV inks.

Photo-Curable Lacquer Sap Resin Based on Urushiol-Mimicking, Tyrosine-Containing Additive

Oriental lacquer sap is attracting considerable attention as a renewable and eco-friendly natural resin with high durability, heat resistance, insulation, insect repellency, and antiseptic and antibacterial properties. However, to ensure excellent coating performance, it is necessary to improve the drying/curing process of lacquer sap with a time-consuming drying time at high humidity [relative humidity (RH), 70-90%] and ambient temperature (20-30 °C). Drawing on an understanding of the polymerization mechanism of urushiol, the main component of the lacquer sap consisted of a water-in-oil (W/O) emulsion, and this study presents an eco-friendly additive that mimics the structure-function of urushiol composed of a polar catechol head group and a nonpolar hydrocarbon tail. A photo-curable lacquer sap was thus developed by adding a tyrosine amino acid-based lipid agent (denoted as Y-ADDA), which allows faster and more effective drying/curing at lower humidity while maintaining the nature-derived properties of lacquer sap. Y-ADDA easily coassembles with urushiol in the W/O emulsion droplets, thereby significantly accelerating the formation of a polymer network along with urushiol during water evaporation leading to fast drying/curing under ultraviolet (UV) light irradiation at low humidity (∼50% RH). The UV-cured lacquer sap resins showed higher performance in terms of film processing and physicochemical properties compared with that of the lacquer containing only tyrosine amino acids without aliphatic tail conjugation, N-(9-fluorenylmethoxycarbonyl)-O-tert-butyl-l-tyrosine Fmoc-Tyr(tBu)-OH. Furthermore, the drying and curing times, film morphology, transmittance, hardness, and adhesion strength of the UV-cured lacquer were markedly superior compared to those of shellac, a general eco-friendly fast-drying primer. The study provides useful strategies and insights to promote the industrial application of lacquer sap resins by employing biocompatible nanoagents developed with an understanding of the curing mechanism of natural resins and from the viewpoint of green and sustainable chemistry perspective.

Syntheses and Characteristics of Urushiol-Based Waterborne UV-Cured Wood Coatings

The manufacture and properties of waterborne UV-cured coatings (WUV coatings) by acetone process based on urushiol for wood finishing were investigated. Firstly, epoxide urushiol (EU) was prepared by reacting urushiol with epichlorohydrin. Secondly, the EU was reacted with acrylic acid to obtain acrylic epoxide urushiol (AEU). Next, the prepolymers were synthesized by the reaction of AEU, 2,2-Bis(hydroxymethyl)propionic acid (DMPA), and isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI), respectively, using acetone as a solvent. The prepolymers were further neutralized by triethylamine (TEA) to obtain ionomers and dispersed in the water. After removing the acetone by vacuum distillation, the polyurethane dispersions (PUDs) were obtained. Finally, the WUV coatings were performed by adding a photoinitiator (Irgacure 2959). The products in the synthesized processes and the properties of the WUV coatings were examined. The results showed that the EU, AEU, prepolymers, and ionomers could be synthesized stably. The PUDs synthesized by the IPDI and HDI had a similar solid content of 25.2% and 26.2%, and similar pH values of 7.8 and 7.6. However, the IPDI-containing PUD displayed lower viscosity, smaller particle size, and a more even polydispersity index. The IPDI-containing WUV film displayed a higher hardness, gloss, and lightfastness. The HDI-containing WUV film possessed superior impact resistance. Both IPDI-containing and HDI-containing WUV films showed excellent adhesion, bending resistance, and mass retention, and demonstrated a potential for wood finishing.

Synthesis of a Compound Phosphorus-Nitrogen Intumescent Flame Retardant for Applications to Raw Lacquer

Raw lacquer (RL) is a natural polymer compound with highly promising applications; however, its inflammable attribute restricts the industrial applications. In this study, melamine is used to formulate tri (1-melamine-2-propanol) phosphate (FR-1), after which it is synthesized with ammonium phosphate (FR-2) and diatomite to form a compound phosphorus-nitrogen intumescent flame retardant (IFR). Next, IFR is used as the filling agent that then cross-links with RL, and as such RL/IFR membranes are formed after the curing. The limiting oxygen index (LOI) measurement, the vertical combustion test (UL-94), the microshape calorimetric analysis (CCT), and the thermal gravimetric analysis (TGA) are conducted to examine the combustion resistance and thermal stability of the membranes. Fourier transform infrared spectroscopy (FT-IR) and electron scanning microscope (SEM) are performed to separately characterize the structure and compatibility; the mechanical properties of the membranes are also evaluated. The vertical combustion test results confirm that with 30 wt% of IFR, RL/IFR membranes acquire 12.3% higher LOI and a vertically combustion of V-0 level. The TGA indicates that RL/IFR membranes demonstrate a greater adhesion level, a higher rigidity, and better luster than pure RL membranes.

Nano-emulsification of oriental lacquer sap by ultrasonic wave propagation: Improvement of thin-film characteristics as a natural resin

Lacquer sap has received much attention as a traditional natural resin because it is a renewable and eco-friendly biopolymer resource unlike artificial coating materials. However, strict drying conditions and long drying times of lacquer sap should be modified to expand its applications. This study presents the first attempt to investigate the effect of different amplitudes of ultrasonic waves on the lacquer sap composed of water-in-oil (W/O) emulsion droplets and the mechanical properties of the resultant film by solvent evaporation. Acoustically induced cavitation via batch ultrasonication facilitates the generation of submicron-sized W/O emulsion. The drying time of sonicated lacquer sap was noticeably shortened as the amplitude of acoustic power increased. Interestingly, the transparency of the film cast from lacquer sap consisting of the smallest emulsion droplets increased significantly, weakening the degree of colour change from caramel-like yellow to dark brown as polymerisation progressed. These are attributed to the effective and frequent contact of laccase enzyme with urushiol at the increased interfacial area of nano-emulsified W/O droplets pulverised by ultrasonic waves. The quinone radical-generation in the interface layer and its transfer to the urushiol oil phase through water-insoluble glycoprotein emulsifier are greatly promoted, resulting in highly cross-linked, dense three-dimensional polymer networks, which also increased the lacquer film hardness after drying. As the emulsion droplet size decreased, the mutual interaction between the catechol moiety of urushiol and the substrates increased, resulting in improved adhesion. The nano-emulsification of the lacquer sap by ultrasonic waves can be used in a simple, effective, and eco-friendly way to shorten the drying time and improve the film characteristics of natural resins. This approach could pave the way for its wide range of applications in industrial fields, taking into account green and sustainable chemistry.

Improved Measurements of the Physical Properties of Oriental Lacquers Using Atomic Force Microscopy and a Nanoindenter

Researchers have widely investigated Oriental lacquers to identify the chemical composition and have elucidated corresponding polymerization mechanisms using rigorous analytical techniques. However, researchers generally test the physical properties of Oriental lacquers by conventional methods that are perhaps overly simplistic. Here, we propose accurate and quantitative methods for evaluating the physical properties of Korean, Vietnamese, and Myanmarese lacquer films using atomic force microscopy (AFM), a nanoindenter, and a 90° peel tester. We obtained surface images of the lacquers in accordance with drying time using scanning electron microscopy and AFM. The Korean lacquer film exhibited fast hardening speed, enhanced hardness, and strong adhesion strength compared with the other lacquers, although the Myanmarese lacquer film had a smoother surface than the Korean lacquer film. We used our characterization approach for evaluating a mixed Korean/Myanmarese (50/50 w/w) lacquer. Our proposed measurement techniques for Oriental lacquer films provided results that agreed with qualitative results from conventional tests. Force–distance curves in AFM and force–displacement with nanoindenter for Oriental lacquer films showed more accurate and quantitative data on the mechanical properties. Thus, researchers will find our approach useful when they optimize the chemical compositions and improve the physical properties of Oriental lacquer films for industrial applications.

Preparation of Nanoscale Urushiol/PAN Films to Evaluate Their Acid Resistance and Protection of Functional PVP Films

Different amounts of urushiol were added to a fixed amount of polyacrylonitrile (PAN) to make nanoscale urushiol/PAN films by the electrospinning method. Electrospinning solutions were prepared by using dimethylformamide (DMF) as the solvent. Nanoscale urushiol/PAN films and conductive Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)/polyvinyl pyrrolidone (PVP) films were prepared by electrospinning. In order to prepare an electrospun sandwich nanoscale film, urushiol/PAN films were deposited as both the top and bottom layers and PEDOT:PSS/PVP film as the inner layer. When the PAN to urushiol ratio was 7:5, the fiber diameter ranged between 150 nm and 200 nm. The single-layer urushiol/PAN film could not be etched after being immersed into 60%, 80%, and 100% sulfuric acid (H2SO4) for 30 min, which indicated the improved acid resistance of the PAN film. The urushiol/PAN film was used to fabricate the sandwich nanoscale films. When the sandwich film was immersed into 80% and 100% H2SO4 solutions for 30 min, the structure remained intact, and the conductive PVP film retained its original properties. Thus, the working environment tolerability of the functional PVP film was increased.

HPLC and ToF‒SIMS Analyses of Toxicodendron vernicifluum Tree Sap Mixed with Other Natural Lacquers

Lacquer sap has been used by humans from antiquitywhen it was treated as a luxury item because of its desirable physical properties. In modern times, although access barriers are lower, lacquer is still considered to be rare and valuable. Thus, low quality, inexpensive Vietnamese and Myanmarese lacquers and cashew nutshell liquid are frequently added to the costly Toxicodendron vernicifluum lacquer sap from Korea, China, and Japan. However, these blended lacquers can diminish the quality of artisan works. The Toxicodendron vernicifluum lacquer saps mixed with other natural lacquers were characterized using time-of-flight secondary-ion mass spectrometry (ToF−SIMS) and high-performance liquid chromatography (HPLC). ToF-SIMS provided the chemical structure of the lacquer monomer, copolymerized dimers, trimers, etc. HPLC provided quantitative analysis of the components of a randomly mixed lacquer. These techniques can be used to control the quality of commercial lacquer sap for the Asian lacquer industry and the traditional conservation of ancient objects.

Quantitative Analysis of Blended Asian Lacquers Using ToF-SIMS, Py-GC/MS and HPLC

Asian lacquer is a special polymeric material tapped from lacquer trees. The tree’s sap is a complex mixture of compounds, such as catechol lipids, polysaccharides, glycoproteins, enzymes, and water. Researchers have not yet quantitatively analyzed blended lacquers. We evaluated the compositions of Japanese and Vietnamese lacquers, and blends of the two, using time-of-flight secondary ion mass spectrometry (ToF–SIMS), pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS), and high-performance liquid chromatography (HPLC). ToF–SIMS provided quantitative results for blended lacquers; provided structural information on polymeric lacquer films; and indicated the presence of dimers of urushiol–urushiol, urushiol–laccol, and laccol–laccol derivatives. We used Py–GC/MS and HPLC to obtain linear calibration curves. The specific peak intensity was a linear function of the ratio of Japanese to Vietnamese lacquer in the blends. For an unknown mixture, all three techniques gave essentially the same results. These quantitative methods will be useful for improving the physical properties of polymeric lacquer films, and evaluating the lacquer quality in industry and historic conservation.

A Study on the Improvement of Using Raw Lacquer and Electrospinning on Properties of PVP Nanofilms

Raw lacquer (RL), ethanol being used as the solvent, was added to polyvinyl pyrrolidone (PVP) and then electrospun into RL/PVP nanofilms. Manufacturing parameters such as RL/PVP ratio, voltage, flow velocity, needle type, and the distance between syringe and the collection board were systematically investigated. A scanning electronic microscope (SEM) was used to observe the surface morphology of nanofilms; the block drop method was used to measure the water contact angle; the mechanical properties of RL/PVP nanofilms of different proportions were tested by universal material testing machine; and Fourier-transform infrared spectroscopy (FT-IR) was used to characterize the structure. Based on the water resistance and acid resistance measurements, the proposed nanofilms demonstrated to be water and acid resistant were successfully produced. The results show that PVP that melts in water becomes incompatible with water after adding raw lacquer, and the acid resistance is greatly improved. Furthermore, the smaller the fiber diameter, the better the mechanical properties of the nanofilms are under low ratio of RL/PVP. With a high proportion of RL/PVP, the inner structure of the nanofilm is denser, and the water resistance and acid resistance are better. The dense structure can protect the inner material of the nanofilms.

Polymerization mechanism of natural lacquer sap with special phase structure

Lacquer sap is a water-in-oil natural emulsion with high viscosity. In nature, it exudes from the phloem of lacquer tree to repair its wounds in the presence of O₂. So far, it is unclear how rapid and smooth polymerization of urushiol is achieved in such a viscous sap. Here, we find that there is a diffuse interface layer with 2.43 nm of thickness between two phases. The interface layer consists of urushiol, urushiol–laccase complex, urushiol–stellacyanin complex and water-insoluble glycoprotein. Polymerization of urushiol is realized by multicomponent synergistic effect. Radicals are first formed by laccase-catalyzed oxidation of urushiol at the interface layer, then are transferred to the urushiol oil phase via wate-insoluble glycoprotein and initiate the polymerization of urushiol there. Stellacyanin inhibits the formation of certain radicals and controls the concentration of phenoxy radicals at the interface layer. Through the inhibition of radicals by stellacyanin and the electron transfer mediated by water-insoluble glycoprotein, the polymerization of urushiol at the interface layer is inhibited. This ensures that O₂ can continuously penetrate into the aqueous phase to oxidize the reduced laccase so that the urushiol polymerization can continue smoothly. This polymerization mechanism provides an idea for developing new chemical reaction systems.

Development of a Negative-Biased Zwitterionic Polypeptide-Based Nanodrug Vehicle for pH-Triggered Cellular Uptake and Accelerated Drug Release

Albumin mimics could be an attractive platform for nanodrug carriers through systematic administration because of high safety and plentiful properties to be adjusted for a high drug efficacy, such as pH-triggered targeting cellular uptake and drug release. In this work, negative-biased zwitterionic nanodrug carriers based on zwitterionic polypeptide chains that mimic albumin were prepared, which have an outermost layer of zwitterionic glutamic acid (E) and lysine (K) pairs with a small amount of aspartic acid (D) to adjust the overall ζ potential. On the other hand, doxorubicin (Dox) was encapsulated in a hydrophobic core by 11-maleimidoundecanoic acid covalently linked with additional cysteine (C) residues on the polypeptide. The results show that the negative-biased zwitterionic nanodrug carriers can sensitively enhance the cellular uptake in responding to a pH change from 7.4 to 6.7 without reversing the ζ potential to a positive charge, leading to accelerating the Dox release rate in a slightly acidic environment through the polypeptide secondary structure change. Moreover, the anionic nanodrug carrier can also be easily enzymatically digested by trypsin for quick drug release. In short, this negative-biased zwitterionic nanodrug delivery vector could be an ideal candidate for a safer tumor inhibition with a high efficacy than conventional synthetic polymer-based ones.

The Effects of Adding Different HALS on the Curing Process, Film Properties and Lightfastness of Refined Oriental Lacquer

Oriental lacquer is a natural polymeric coating with a satiny texture and excellent characteristics, such as chemical resistance and durability. However, the poor lightfastness resulted in the natural aromatic structures of the urushiol structures limited its suitability for outdoor application. This study aimed at the improvement of the lightfastness by adding the different hindered amine light stafbilizers (HALS) with 2 phr addition as well as the effects on the coating and film property of the refined oriental lacquers (RL). The Cryptomeria japonica plate, glass sheets, and the other substrates were used for finishing. The results showed that the lightfastness of RL film was obviously improved by adding 2 phr HALS of Bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (H90) containing -NH group and Bis (1,2,2,6,6-pentamethyl-4-piperidinyl)-[[3,5-bis(1,1-dimethyl ethyl) -4-hydroxyphenyl] methyl] butylmalonate (H60) containing -NCH₃ groups. The HALS additions increased the pH value of RL and improved the activities of laccase-catalyzed reaction. Meanwhile, the oxidative polymerization of the side chains of RL was inhibited, caused by a radical scavenging ability of HALS. The changes in the drying process affected not only the curing time, but also the film properties. Among the 2 phr additions of different HALS, the film containing H90 had the best lightfastness. Meanwhile, it kept the most similar properties with RL and shortened the drying time of RL, and it was selected as the best HALS addition under 2 phr in this study.

Ecofriendly Catechol Lipid Bioresin for Low-Temperature Processed Electrode Patterns with Strong Durability

We demonstrated catechol lipid-based bioresin, which is collected from lacquer trees, to produce conductive pastes that can be processed at low temperatures, which are highly adhesive and multidurable. Our conductive paste, which consists of catechol lipid-based urushiol resin and a multimodal mixture of silver fillers, exhibited stable dispersion with shear thinning properties. The urushiol lacquer induced spontaneous reduction of silver salt at the surface of the silver fillers, thereby contributing to lower the contact resistance between conductive fillers in the electrical conduction. Furthermore, the directional volume shrinkage of the urushiol lacquer matrix in a cross-linking reaction resulted in a highly ordered microstructure of the silver fillers with layer-by-layer stacking of the silver flakes. This structure contributed to the improvement of the electrical contact between fillers as well as excellent mechanical hardness, anti-scratch capability, and the long-term environmental stability of the conductive films. Conductive films based on the silver paste with urushiol lacquer exhibited low electrical resistivity below 4.4 × 10^-5 Ω cm, 5B-class strong adhesion strength, and high hardness exceeding 200 MPa. Finally, we demonstrated the facile room-temperature processability and screen printability of the UL-Ag paste by fabricating a printed antenna and three-dimensional (3D) electrode assembly based on a plastic 3D block.

Catechol oxidation: considerations in the design of wet adhesive materials

Electron-withdrawing substituents slow the rate of oxidation of substituted catechols by O₂: a Hammett analysis.

Bio-inspired electrochemical corrosion coatings derived from graphene/natural lacquer composites

To develop green efficient anti-corrosion coatings, graphene/lacquer composite coatings were demonstrated.

Intrinsic Hydrophobic Cairnlike Multilayer Films for Antibacterial Effect with Enhanced Durability

One important aspect of nanotechnology includes thin films capable of being applied to a wide variety of surfaces. Indispensable functions of films include controlled surface energy, stability, and biocompatibility in physiological systems. In this study, we explored the ancient Asian coating material "lacquer" to enhance the physiological and mechanical stability of nanofilms. Lacquer is extracted from the lacquer tree and its main component called urushiol, which is a small molecule that can produce an extremely strong coating. Taking full advantage of layer-by-layer assembly techniques, we successfully fabricated urushiol-based thin films composed of small molecule/polymer multilayers by controlling their molecular interaction. Unique cairnlike nanostructures in this film, produced by urushiol particles, have advantages of intrinsic hydrophobicity and durability against mechanical stimuli at physiological environment. We demonstrated the stability tests as well as the antimicrobial effects of this film.

Polyphenols: From Plants to a Variety of Food and Nonfood Uses

Polyphenols are major plant secondary metabolites, structurally extremely diverse, essential for a variety of functions in plants, responsible for major organoleptic and nutritional properties of plant-derived foods, and useful for numerous practical applications. During the 27th International Conference on Polyphenols and 8th Tannin Conference, held jointly in September 2014 in Nagoya, Japan (ICP2014), the latest advances in polyphenol research have been presented. These include advances in polyphenol chemistry, physicochemistry, and materials science; their biosynthesis, genetics, and metabolic engineering; and their role in plant interactions with the environment, in nutrition and health, and in natural medicine. This special issue presents a selection of research papers presented at the meeting, covering these different fields. Major recent progress and perspectives in these areas are also outlined in this introductory paper.

Prepolymerization of Lacquer Sap under Pure Oxygen Atmosphere and Its Effects on the Properties of Lacquer Film

A series of lacquer saps were prepared by prepolymerization under oxygen atmosphere. The prepolymerization process was investigated by GPC, UV-Vis, FT-IR, NMR, and microscope. The results showed that the polymerization of urushiol monomer was accelerated. The content of monomer in the lacquer sap swiftly decreased from 82.68% to 47.75% in 0.5 h. The mechanism of polymerization was complex and was involved in the coupling reaction of phenyl ring, the addition reaction of the unsaturated carbon-carbon double bond groups with urushiol hydroxyl groups, and other reactions that occurred on the side chains. In addition, the prepolymerization also improved significantly the drying property of lacquer film, especially at low relative humidity. At the same time, the sizes of the water drops in the lacquer saps significantly decreased with increasing the stirring time and the surface of lacquer film became smoother, which resulted in its excellent gloss (109–125). Due to the prepolymerization, the pencil hardness and the thermal stability of lacquer film were slightly improved as well.