Rosin acid and SiO2 modified cotton fabric to prepare fluorine-free durable superhydrophobic coating for oil-water separation.

Currently, fluorides and long-chain aliphatic compounds are the most frequent low surface energy chemicals utilized in the preparation of superhydrophobic coatings, but associated environmental risks and instability restrict their potential application in oil-water separation. This research described a superhydrophobic coating based on rosin acid and SiO2 modified cotton fabric to overcome this challenge. By means of spray impregnation and UV-assisted click reaction, sulfhydryl modified rosin acid (RA), Octavinyl-POSS, and SiO2 were grafted onto the surface of cotton fabric to obtain RA-SiO2 superhydrophobic coating with rough surfaces such as lotus leaf and low surface energy. The RA-SiO2 superhydrophobic coating had favorable self-cleaning ability, and also adsorbed various light and heavy oils to achieve efficient separation of oil-water mixtures. The separation efficiency was 96.3% and the permeate flux was 6110.84 (L⋅m-2⋅h-1) after 10 repetitions. The RA-SiO2 superhydrophobic coating was found to be effective in separating oil-in-water and oil-in-water emulsions, and the separation mechanism was elaborated. In addition, it could effectively separate emulsions even after mechanical abrasion and chemical immersion, and had excellent stability. The fluorine-free and environmentally friendly low-cost superhydrophobic coating based on rosin acid is expected to play a significant potential in oil-water separation applications due to its excellent separation performance.

Theoretical study on the radical scavenging activity and mechanism of four kinds of Gnetin molecule.

As an important subgroup of resveratrol oligomers, Gnetins received much attention due to their antioxidants. The four Gnetin molecules are divided into two major categories according to different structures, type-A (Gnetin-C, Gnetin-D) and type-B (Gnetin-L, Gnetin-F). Density functional theory (DFT) has been performed thermodynamically and kinetically in detail to analyze the structure and antioxidant activity of four Gnetins toward OH/OOH radical in the gas and solvents phase with four possible antioxidant mechanisms, namely, Hydrogen-atom transfer (HAT), Single electron transfer followed by proton transfer (SET-PT), Sequential proton-loss electron transfer (SPLET), and Radical adduct formation (RAF). From these calculations; Gnetins' order of antioxidant activity was estimated as: Gnetin-C ≈ Gnetin-L > Resveratrol > Gnetin-D > Gnetin-F. All investigations suggested that type A has a higher radical scavenging activity compared to type B. On the basis of the structure-activity relationship, type A structure may have more vital antioxidant potential in the future.

Construction of antimicrobial and biocompatible cotton textile based on quaternary ammonium salt from rosin acid.

Antimicrobial cotton textiles (CT) show great promise for wound dressings. However, modifying CTs to have antimicrobial properties requires balancing the killing of microbes while protecting normal cells. In this study, the surface of CT was modified using maleopimaric acid quaternary ammonium cations (MPA-N+) from rosin acid. The surfaces morphology and chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), which confirmed that the MPA-N+ modified CT (CT-g-MPA-N+) was prepared. CT-g-MPA-N+ shows strong and broad spectrum antimicrobial activities against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus). It also exhibits prominent durability of antimicrobial capability even after soaking in PBS for 6 days, and can effectively inhibit bacterial biofilm formation. Most importantly, the excellent biocompatibility of CT-g-MPA-N+ was verified by hemocompatible and cytotoxic assays. This work is believed to be promising method to prepare antimicrobial cotton textiles by surface modification and suggest the great potential application in wound dressing.

Cellulose-based polymeric emulsifier stabilized poly(N-vinylcaprolactam) hydrogel with temperature and pH responsiveness.

N-vinylcaprolactam (NVCL) is a temperature-responsive monomer, which is widely used for preparing responsive hydrogels. However, poor water solubility of NVCL necessitates the use of emulsifiers for better dispersion. Hydrolyzed epoxy soybean oil-grafted hydroxyethyl cellulose (H-ESO-HEC) polymeric emulsifier has excellent emulsifying properties, and the carboxyl groups afford pH-responsiveness to the hydrogels. A novel temperature- and pH-responsive cellulose-based hydrogel was prepared by combining NVCL and H-ESO-HEC. The hydrogel morphology, thermal stability, and swelling capacity were characterized, and it was also used as a dual-responsive drug preservative carrier. Scanning electron microscopy and thermogravimetric analysis confirmed the porous structure and good thermal stability, respectively, of the hydrogel. The hydrogel displayed a temperature- and pH-dependent swelling behavior and improved swelling capacity. The swelling behavior agreed well with the Korsmeyer-Peppas model and Schott's second-order kinetic model. The dual-responsive hydrogel has significant potential in the drug delivery systems owing to its biocompatibility and temperature and pH sensitivity.

Mechanical reinforcement of room-temperature-vulcanized silicone rubber using modified cellulose nanocrystals as cross-linker and nanofiller.

Despite the excellent properties of room-temperature-vulcanized silicone rubber (RTVSR), such as good temperature resistance, low toxicity, and low cost, its industrial application is limited owing to its poor mechanical properties. Herein, we employed cellulose nanocrystals modified by acid hydrolysis and reaction with 3-isocyanatopropyltrimethoxysilane (ICNCs) as the cross-linking agent to reinforce RTVSR. Structural analyses of ICNCs confirmed the chemical modification of the cellulose nanocrystal surface and preservation of the crystalline structure. The ICNCs improved the thermostability of RTVSR and also acted as a nanoscale filler in the RTVSR/ICNCs nanocomposite. The thermostability and mechanical properties of RTVSR/ICNCs expectedly improved with increased ICNC content. Moreover, compared with unmodified silicone rubber, RTVSR/ICNCs nanocomposites exhibited high haze and high transparency. Our work indicates that ICNCs are well dispersed in the RTVSR matrix and effectively improve its properties.