Yanlian Xu

On the UV-Induced Polymeric Behavior of Chinese Lacquer

To dry Chinese lacquer rapidly for the protection and restoration of archeological findings coated by lacquer or excavated lacquer wares and the development of new application of this lacquer, we carried out UV curing technology to improve its curing rate using a high-pressure mercury lamp as a UV source in the absence of any additional photoinitiator. The effects of mainly specific components in Chinese lacquer sap and the role of each reactive group of urushiol, namely hydroxyl groups, hydrogen on the phenyl ring, and olefins in the side chain, in the course of UV exposure were well-investigated. The UV-cured Chinese lacquer films were also characterized by FT-IR, (1)H NMR, SEM, TGA, and Py-GC/MS. The results showed that urushiol was the main component to form Chinese lacquer films, and decomposed to generate the urushiol semiquinone radicals, which sequentially induced the polymerization of Chinese lacquer by radical polymerization, as well as radical substitution under UV irradiation. In addition, the TG analysis suggested that polysaccharide and glycoproteins were integrated with the UV-cured films by covalent bonding. Furthermore, this method could be suitable to fast cure other phenol bearing long aliphatic unsaturated chain, such as CNSL.

Preparation and properties of raw lacquer/multihydroxyl polyacrylate/organophilic montmorillonite nanocomposites

Raw lacquer (RLA) has been widely used indoors for centuries in Asia. But its weak UV-resistant property limited its outdoor application. In this article, the UV-resistant property of lacquer film was significantly improved by solution intercalation method. The intercalated nanocomposites were obtained from RLA, multihydroxyl polyacrylate resin (MPA), and organophilic montmorillonite (OMMT). The structure and morphology of the RLA/MPA/OMMT nanocomposites were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The variation of the film gloss and impact strength with different UV exposure time was also investigated. Owing to the dispersion of nanometer-sized OMMT in polymer matrix, the RLA/MPA/OMMT nanocomposites exhibited improved UV-resistant property. When the OMMT content is 3.0xa0wt%, the best physical–mechanical properties can be obtained. These results indicated that the solution intercalation with nanoparticles was an efficient and convenient method to improve the properties of raw lacquer.

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

Protective corrosion coatings are preferably composed of available, environmentally friendly, and low-volatility organic compounds. Herein, new excellent corrosion graphene/raw lacquer composite coatings were formed, in which waterborne graphene was modified by taking lignin tripolymer (LT) as an aqueous stabilizer and subsequently adding to raw lacquer (RL). Graphene/lacquer composite coatings were achieved by an eco-friendly fabrication process. The structure and thermostability of the lignin derivative were studied by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG), respectively, while the composition of the LT was characterized by Raman spectrometry. And the experimental result revealed that LT was an effective graphene dispersant (LTG) up to 60 d without any precipitation. Besides, the SEM of the graphene/lacquer coatings revealed that the excellent protection properties were highly attributable to the formation of a very rough surface, because of the highly dispersed nature of the graphene nanoparticles. Also, the corrosion behavior of the composite coatings on a metal substrate were studied by polarization curve analysis and electrochemical impedance spectroscopy (EIS). According to the electrochemical corrosion tests, the lacquer composite coating with 5 wt% LTG dispersion (RL/LTG-5, containing 0.3 wt% graphene) possessed excellent corrosion resistance, making it suitable for protecting bare metal substrates.

Effect of Silane on the Active Aging Resistance and Anticorrosive Behaviors of Natural Lacquer

Environmentally friendly and renewable hybrid lacquer coatings with excellent aging resistant and anticorrosion properties were studied. The coatings were prepared using raw lacquer coupled with the silane agent 3-aminopropyltriethoxysilane or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane via an eco-friendly sol–gel preparation process. The physical–mechanical properties, thermal stability, aging resistance, and anticorrosion properties of the as-prepared coatings were analyzed. Additionally, the surface of the coatings before and after an accelerated aging treatment was studied by scanning electron microscopy and X-ray photoelectron spectroscopy. The results revealed that the hybrid lacquer coating A (with a raw lacquer-to-APTES mass ratio of 1.8:1) resulted in films with a significantly enhanced antiaging effect (e.g., six times higher than that of lacquer at a gloss loss rate of 30%). Besides, this film revealed an exceptional anticorrosion performance (with the lowest corrosion current Icorr = 2.476 × 10–10 A·cm–2) and a high protection efficiency (99.99 and 94.10%), as demonstrated by its electrochemical characteristics. Furthermore, all films exhibited a good barrier because of their dense structure, which prevents the corrosive medium from penetrating the coating during the salt spray test analysis after 1000 h. And the coating A relatively layered was distributing any significant cancaves, integrity better than all coatings studied, indicating that the based electrolyte was easier to penetrate it after salt spraying 2000 h.

Fabrication of polyurushiol/Ag composite porous films using an in situ photoreduction method

In this work, polyurushiol (PUS) was synthesized through a Friedel–Crafts reaction using brönsted acid as a catalyst. The product was then utilized in the fabrication of honeycomb porous films by breath figures (BFs). The PUS porous films were subsequently exposed to a high pressure mercury lamp for several seconds (5–30xa0s). An AgNO3 solution was then dripped onto the surface of films to form PUS/Ag composite porous films through the in situ photoreduction method, avoiding the use of harmful reducing agents. Key preparation factors, including solvent type, UV irradiation time and AgNO3 concentration, were systematically investigated. The composite films were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Ag particles (approximate size of 50xa0nm) were formed on the surface of PUS porous films when water was used as a solvent. In addition, increased AgNO3 concentration or UV irradiation time facilitated a change in the conductivity state of PUS/Ag porous films from insulator to semiconductor. The as-prepared PUS/Ag composite porous films provided excellent electronic properties and thus provided significant potential for future application in various fields.Graphical abstract

Synthesis and properties of poly(1,3-dialkoxybenzene)s from facile solvent-free grinding oxidative coupling polymerization

Soluble conjugated aromatic poly(1,3-dialkoxybenzene)s were obtained in high yield up to 80% in 30xa0min by grinding 1,3-dialkoxybenzene with anhydrous FeCl3 powder in a mortar at ambient and solvent-free condition. The polymers were characterized by FT-IR, 1H-NMR, 13C-NMR, and gel permeation chromatography. The structure of the aromatic rings linkage at meta-position was confirmed. Thermogravimetric analysis, UV–Vis, fluorescence spectroscopy, and four-probe a.c. technique were used to probe the thermal, optical, and electrical properties of the polymers. The polymers displayed high thermostability with the decomposition temperatures at about 382–388xa0°C. The optical energy gap (Eg) of the polymers was 4.23xa0eV and electrical conductivity at room temperature was 10−6xa0Sxa0cm−1. The fluorescence curve of the polymers displayed the maximum at 344xa0nm in CH2Cl2 solution. The morphology of the polymers was determined by X-ray diffraction and scanning electron microscope technique.