Modification of Chinese fir with alkyl ketene dimer (AKD): Processing and characterization

A process for the chemical modification of Chinese fir with alkyl ketene dimer (AKD) was studied. The hydrophobicity of the resulting products was evaluated by characterization of the equilibrium moisture content, water-surface contact angle, water absorption coefficient, and anti-swelling efficiency. The results indicated that when 5% AKD solution was used, the modified wood generally showed good hydrophobicity and improved dimensional stability. The result of boiling water and hexane extraction tests showed that the modified fir possessed very stable hydrophobicity

MODULUS OF ELASTICITY AND HARDNESS OF COMPRESSION AND OPPOSITE WOOD CELL WALLS OF MASSON PINE

Compression wood is commonly found in Masson pine. To evaluate the mechanical properties of the cell wall of Masson pine compression and opposite wood, nanoindentation was used. The results showed that the average values of hardness and cell wall modulus of elasticity of opposite wood were slightly higher than those of compression wood. With increasing age of the annual ring, the modulus of elasticity showed a negative correlation with microfibril angle, but a weak correlation was observed for hardness. In opposite and compression wood from the same annual ring, the differences in average values of modulus of elasticity and hardness were small. These slight differences were explained by the change of microfibril angle (MFA), the press-in mode of nanoindentation, and the special structure of compression wood. The mechanical properties were almost the same for early, transition, and late wood in a mature annual ring of opposite wood. It can therefore be inferred that the average modulus of elasticity (MOE) and hardness of the cell walls in a mature annual ring were not being affected by cell wall thickness

Fluorinated Raspberry-like Polymer Particles for Superamphiphobic Coatings

Raspberry-like (RB) polymer particles were prepared, fluorinated, and cast onto glass plates to yield highly water- and oil-repellant superamphiphobic particulate coatings. To procure the RB particles, glycidyl-bearing 212 and 332 nm particles (abbreviated as <i>s</i>-GMA and <i>l</i>-GMA, respectively) were first prepared via surfactant-free free radical emulsion polymerization. Reacting the glycidyl groups of the <i>l</i>-GMA particles with 2,2′-(ethylenedioxy)­bis­(ethylamine) (EDEA) produced large amine-functionalized particles (<i>l</i>-NH₂). The <i>l</i>-NH₂ particles were then reacted with an excess of the <i>s</i>-GMA particles to create RB particles. For surface fluorination, the residual glycidyl groups of the smaller <i>s</i>-GMA particles surrounding the central <i>l</i>-NH₂ core of the RB particles were first converted to amino groups by reaction with EDEA. The purified amino-bearing particles were subsequently reacted with an excess of a statistical copolymer poly­(2-(perfluorooctyl)­ethyl methacrylate-<i>co</i>-glycidyl methacrylate), P­(FOEMA-<i>co</i>-GMA). Casting these particles onto glass plates yielded particulate films that exhibited static contact angles of 165 ± 2°, 155 ± 3°, 152 ± 4°, and 143 ± 1° and droplet rolling angles of <1 °, <1 °, 7 ± 2°, and 13 ± 2° for water, diiodomethane, corn-based cooking oil, and hexadecane droplets, respectively. These results demonstrated that this practical bottom-up approach could be used to produce superamphiphobic coatings

Mussel-Inspired Green Metallization of Silver Nanoparticles on Cellulose Nanocrystals and Their Enhanced Catalytic Reduction of 4‑Nitrophenol in the Presence of β‑Cyclodextrin

A green approach to anchor silver nanoparticles (AgNPs) onto the surface of cellulose nanocrystals (CNCs) coated with mussel-inspired polydopamine (PDA) at room temperature in the absence of a stabilizer and a reducing agent is proposed. The resulting nanohybrids possessed a core–shell structure with numerous “satellites” of silver nanoparticles decorating the CNC surface. The nanocatalyst displayed superior dispersibility over pristine AgNPs and was six times more efficient in catalyzing the reduction of 4-nitrophenol. By associating the CNC hybrid with β-cyclodextrin to promote host–guest interactions, the catalytic process was accelerated. The associated physicochemical parameters associated with the catalytic process were investigated and compared

Strategy for Synthesizing Porous Cellulose Nanocrystal Supported Metal Nanocatalysts

This paper describes a novel platform to prepare small and uniformly distributed metal nanoparticles (MNPs) on cellulose nanocrystals for use as high performance sustainable nanocatalysts. The model platinum or palladium NPs (1–2 nm in size) were immobilized and chemically reduced onto melamine-formaldehyde (MF) coated cellulose nanocrystals (MFCNCs). The MF coating was critical for the uniform generation and size-control of MNPs. The contribution of MF resin to optimal MNP synthesis includes: (1) increased surface area with its spongelike structure, (2) enhanced affinity to metals through chelation with nitrogen functionalities, and (3) effective MNP size control due to the mesoporous structure. The MNP/MFCNC system significantly improved catalytic activity as demonstrated by the reduction of 4-nitrophenol with Pd/MFCNCs with a turnover frequency of 3168 h^–1. Our synthesis does not require any complicated apparatus or harsh reaction conditions. The proposed strategy is well-suited for the synthesis of a wide range of metal nanocatalysts characterized by a particle size of 1 to 2 nm and superior catalytic activity