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 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.

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.

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.