Seaweed-inspired underwater anti-oil-fouling and anti-fogging coating with mechanical durability

Ecofriendly fabrication of anti-oil-fouling materials is of interest. Surfaces with underwater superoleophobicity have been fabricated which exhibit limited mechanical durability and water resistance. In this study, we report on a bioinspired bilayer design of a transparent anti-oil-fouling coating. Seaweed surfaces show anti-oil-fouling in the sea due to its high surface hydration ability. Mussels can adhere tightly onto a surface with good stability in the sea by virtue of its levodopa-containing secretions. The surface layer was fabricated using a crosslinked combination of carboxymethyl cellulose (CMC) and sodium alginate (AlgS) inspired by seaweed, with the addition of calcium ions. Polydopamine (PDA), a derivative of levodopa, was used as the underlayer to enhance bonding strength and water resistance. Oil that adhered to the coated surface was spontaneously detached upon immersion in water. The mechanism underlying this anti-oil-fouling effect was elucidated using Gibbs free energy theory. The coating exhibited mechanical durability and water resistance. The coating is transparent and preserves the original color of the substrate. The coated glass showed stable anti-fogging and anti-frost performance. These coatings hold promise for a wide range of anti-oil-fouling applications.

Microporous metallic scaffolds supported liquid infused icephobic construction

HYPOTHESIS

Ice accretion on component surfaces often causes severe impacts or accidents. Liquid-infused surfaces (LIS) have drawn much attention as icephobic materials for ice mitigation in recent years due to their outstanding icephobicity. However, the durability of LIS constructions remains a big challenge, including mechanical vulnerability and rapid depletion of lubricants. The practical applications of LIS materials are significantly restrained, and the full potential of LIS for ice prevention has yet to be demonstrated.

EXPERIMENTS

A universal approach was proposed to introduce microporous metallic scaffolds in the LIS construction to increase the applicability and durability, and to prompt the potential of LIS for ice mitigation. Microporous Ni scaffolds were chosen to integrate with polydimethylsiloxane modified by silicone oil addition.

FINDINGS

The new LIS construction demonstrated significantly improved durability in icing/de-icing cyclic test, and it also offered a solution for the rapid oil depletion by restraining the deformation of the matrix material. Low ice adhesion strength could be maintained via a micro-crack initiation mechanism. The results indicated that the multi-phase LIS construction consisting of microporous Ni scaffolds effectively addressed the shackles of the icephobicity deterioration of LIS materials, confirming a new design strategy for the R&D of icephobic surfaces.

Pelletizing of lignocellulosic wastes as an environmentally friendly solution for the energy supply: insights on the properties of pellets from Brazilian biomasses

In the context of the circular bioeconomy and cleaner production, the incorporation of the by-products of plant biomass production in the bioenergy chain is fundamental. However, lignocellulosic wastes have properties that hinder their use for the production of biofuels. This study aims to evaluate how blends of lignocellulosic wastes improve the physical, chemical, and mechanical quality of pellets destined to the industrial sector, and to identify the challenges associated with the use of agroforestry biomass as raw material for pelletizing. Pellets were produced from blends of soybean wastes, sorghum wastes, pine needles, rice powder, Eucalyptus sawdust, and charcoal fines. Additionally, pure pellets composed of soybean wastes, sugarcane bagasse, and pine wood were evaluated. The effect of biomass type on the energy density, ash content, net heating value, and ultimate analysis was significant. The pellets produced with soybean wastes presented high contents of N (3.5-4.9%) and ashes (16.4-26.7%), besides low mechanical durability (≤ 96%), hindering its commercialization for industrial purposes. Pellets with sugarcane bagasse presented N (1.5%), S (0.03%), ashes (5.6%), mechanical durability (96.6%), and net heating value (15.1 MJ kg^-1), suitable for industrial energy use in accordance with ISO 17225-6. The high N and ash contents and the low mechanical durability are the greatest challenges for the energy use of pellets produced from Brazilian agroforestry wastes.

Core-Shell Fiber-Based 2D Woven Triboelectric Nanogenerator for Effective Motion Energy Harvesting

Personal electronic devices have a general development trend of miniaturization, functionality, and wearability. Their wireless, sustainable, and independent operation is critically important, which requests new power technologies that can harvest the ambient environmental energy. Here, we report a new kind of 2D woven wearable triboelectric nanogenerator (2DW-WTNG) composed of core-shell fibers via the twisting process and weaving process in the textile manufacture. The 2DW-WTNG can convert the body motion energy into electricity with an output current of 575 nA and an output voltage of 6.35 V. At an external load of 50 MΩ, it generated a maximum power density of 2.33 mW/m². Electricity can be produced from the 2DW-WTNG driven in arbitrary in-plane directions. A tiny displacement of 0.4 mm can drive the 2DW-WTNG, which verified its capability to harvest energy from small human movement. The robust 2DW-WTNG can work continuously for 12 h without obvious performance degradation.