Mechanically Robust and Flexible GO/PI Hybrid Aerogels as Highly Efficient Oil Absorbents

Hybrid and Single-Component Flexible Aerogels for Biomedical Applications: A Review

The inherent disadvantages of traditional non-flexible aerogels, such as high fragility and moisture sensitivity, severely restrict their applications. To address these issues and make the aerogels efficient, especially for advanced medical applications, different techniques have been used to incorporate flexibility in aerogel materials. In recent years, a great boom in flexible aerogels has been observed, which has enabled them to be used in high-tech biomedical applications. The current study comprises a comprehensive review of the preparation techniques of pure polymeric-based hybrid and single-component aerogels and their use in biomedical applications. The biomedical applications of these hybrid aerogels will also be reviewed and discussed, where the flexible polymeric components in the aerogels provide the main contribution. The combination of highly controlled porosity, large internal surfaces, flexibility, and the ability to conform into 3D interconnected structures support versatile properties, which are required for numerous potential medical applications such as tissue engineering; drug delivery reservoir systems; biomedical implants like heart stents, pacemakers, and artificial heart valves; disease diagnosis; and the development of antibacterial materials. The present review also explores the different mechanical, chemical, and physical properties in numerical values, which are most wanted for the fabrication of different materials used in the biomedical fields.

Water-Based Route for Dopamine and Reduced Graphene Oxide Aerogel Production

Water pollution caused by domestic waste oil and accidents with oil/organic spill needs immediate remediation, as such a pollution causes serious threats to health and the environment. Development of absorbent materials for the treatment of oil-polluted waters in a green and energy-efficient manner is highly desired. In this study, a green and simple strategy is proposed to prepare aerogels by hydrothermal reaction of graphene oxide (GO) dispersions using dopamine (DOPA) as the cross-linker. Concentrations of GO and DOPA were changed to determine their effects on absorption capacities. Aerogels produced had low densities ranging from 2.90 to 4.34 mg/cm3. Various organics, diesel oil, and sunflower oil were used to evaluate the absorption capacity of aerogels. It was observed that even with a mild thermal reduction at 150 °C, aerogels exhibited very high absorption capacities of up to 445 mg/mg. The produced aerogels showed high reusability (80%) and structural stability even after 10 absorption/desorption cycles. They possess great potential in oil/organic removal and water treatment based on their high absorption capacities and performances in separating organics/liquids from water.

The Tribological and Mechanical Properties of PI/PAI/EP Polymer Coating under Oil Lubrication, Seawater Corrosion and Dry Sliding Wear

To investigate the tribological performance of a copper alloy engine bearing under oil lubrication, seawater corrosion and dry sliding wear, three different PI/PAI/EP coatings consisting of 1.5 wt% Ce2O3, 2 wt% Ce2O3, 2.5 wt% Ce2O3 were designed, respectively. These designed coatings were prepared on the surface of CuPb22Sn2.5 copper alloy using a liquid spraying process. The tribological properties of these coatings under different working conditions were tested. The results show that the hardness of the coating decreases gradually with the addition of Ce2O3, and the agglomeration of Ce2O3 is the main reason for the decrease of hardness. The wear amount of the coating increases first and then decreases with the increase of Ce2O3 content under dry sliding wear. The wear mechanism is abrasive wear under the condition of seawater. The wear resistance of the coating decreases with the increase of Ce2O3 content. The wear resistance of the coating with 1.5 wt% Ce2O3 is the best under-seawater corrosion. Although Ce2O3 has corrosion resistance, the coating of 2.5 wt% Ce2O3 has the worst wear resistance under seawater conditions due to severe wear caused by agglomeration. Under oil lubrication conditions, the frictional coefficient of the coating is stable. The lubricating oil film has a good lubrication and protection effect.