Yulin Shi

UV‐Triggered Surface‐Initiated Polymerization from Colorless Green Tea Polyphenol‐Coated Surfaces

A facile and versatile approach to constructing colorless surface coatings based on green tea polyphenols is reported, which can further act as a photoinitiating layer to initiate radical polymerization. These colorless green tea polyphenol coatings are capable of successfully photografting polymer brushes, and the resulting polymer brush patterns show spatial shape adjustability by masked UV irradiation. Both surface modifications and photografted polymer brushes do not alter the original color of the substrates. This method could be promising for the development of surface modifications.

Preparation of avermectin microcapsules with anti-photodegradation and slow-release by the assembly of lignin derivatives

Avermectin (Av) is a highly efficient pesticide against a variety of nematodes and is widely used in agriculture. However, it is susceptible to oxidation and photolysis, resulting in instability under UV irradiation and a short half-life. Herein, a rapid and low-cost approach was reported on preparing alkyl chain-coupled lignosulfonate-based polymer coated Av (Av@ALS) microcapsules by the self-assembly of natural and environmentally friendly lignin derivatives. The morphology and UV-shielding of Av@ALS microcapsules were investigated by SEM, EDX, TEM, DLS, FTIR and UV-vis spectroscopy. The self-assembly process and release kinetics of Av@ALS microcapsules were also studied in detail. The results show Av@ALS microcapsules have remarkable avermectin loading ability (up to 57.01% (w/w)), excellent slow-release properties and especially superior UV-shielding properties. The ease and low cost of the assembly process, combined with the natural materials, allows the coating method to open a new avenue for the field of efficient utilization of pesticide.

Engineering plasmonic Ag/AgCl–polydopamine–carbon nitride composites for enhanced photocatalytic activity based on mussel chemistry

The interfacial interaction plays an important role in composites, by affecting the physical and chemical properties of those composites. Herein, we present a simple and versatile approach for the construction of plasmonic Ag/AgCl–polydopamine–CN (SPCN) composites with enhanced photocatalytic properties by mussel chemistry. Dopamine hydrochloride acts as both the reactant and the reducing agent, and the product polydopamine (PDA) serves as the adhesive layer and the electron transfer bridge. The photocatalytic degradation of rhodamine B (RhB) shows that the SPCN50 composite displays excellent photocatalytic activity. A radical trapping experiment indicates that holes are the main oxidative species in the photocatalytic process, and a possible photocatalytic mechanism is proposed. All the results prove that PDA indeed improves the separation efficiency of photogenerated carriers and the photocatalytic activity. This work may provide a green, universal method to synthesize plasmonic photocatalytic composites with high catalytic performance.

Enhanced Oxygen Vacancies in a Two-Dimensional MnAl-Layered Double Oxide Prepared via Flash Nanoprecipitation Offers High Selective Catalytic Reduction of NOx with NH3

A two-dimensional MnAl-layered double oxide (LDO) was obtained by flash nanoprecipitation method (FNP) and used for the selective catalytic reduction of NOx with NH3. The MnAl-LDO (FNP) catalyst formed a particle size of 114.9 nm. Further characterization exhibited rich oxygen vacancies and strong redox property to promote the catalytic activity at low temperature. The MnAl-LDO (FNP) catalyst performed excellent NO conversion above 80% at the temperature range of 100–400 °C, and N2 selectivity above 90% below 200 °C, with a gas hourly space velocity (GHSV) of 60,000 h−1, and a NO concentration of 500 ppm. The maximum NO conversion is 100% at 200 °C; when the temperature in 150–250 °C, the NO conversion can also reach 95%. The remarkable low-temperature catalytic performance of the MnAl-LDO (FNP) catalyst presented potential applications for controlling NO emissions on the account of the presentation of oxygen vacancies.

Amphoteric starch derivatives as reusable flocculant for heavy-metal removal

A pH-responsive amphoteric starch derivative (PRAS) bearing dual functional groups (amino and carboxyl groups) was prepared through etherification of starch with 2-chloro-4,6-diglycino-[1,3,5]-triazine. PRAS exhibits a reversible pH-response property in aqueous solution. The attractive property of PRAS is that it could be used as an effective flocculant for heavy metal-ion (e.g. Cu(II) and Zn(II)) removal from wastewater by changing pH. The transition of hydrophobicity–hydrophilicity would produce shrinkage of the polymer matrix, facilitating the release of heavy-metal ions from the saturated flocculant. As an ideal flocculant PRAS displayed outstanding stability and reproducibility, whose remove rate for Cu(II) and Zn(II) remained at 93% and 91% after three flocculation/regeneration cycles.

Thermo- and pH-responsive starch derivatives for smart window

A thermo and pH dual-responsive starch (TPDS) was successfully synthesized by etherification, in which butyl glycidyl ether (BGE) was used as the hydrophobic reagent followed by addition of 2-chloro-4, 6-diglycino-[1,3,5]-triazine (CDT) groups. The obtained materials were characterized by Fourier transform-infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR) and elemental analysis to confirm the structure and the average substitution degree of BGE and CDT on starch molecule. It was observed that the lower critical solution temperature (LCST) of the TPDS could be modulated from 31 °C to 47 °C by increasing pH of the solution. The effects of pH and the concentration of such materials on the energy-saving performance of TPDS which could be potentially used as smart windows were investigated by UV-vis-NIR spectrophotometry. The solar modulating ability (△Tsol) and the luminous transmittance (△Tlum) of the sample were 40.1% and 47.1% when 10 g/L TPDS was chosen at pH 3. The results indicate that TPDS exhibits excellent optical performance with a controllable LCST, which shows great potential for the application as a smart window.