Mussel-inspired polydopamine microspheres self-adhered on natural hemp fibers for marine uranium harvesting and photothermal-enhanced antifouling properties

Polydopamine-functionalized capsules: From design to applications

In recent years, polydopamine (PDA)-functionalized capsules have garnered significant interest from researchers in the field of materials, owing to its remarkable properties of adhesion, biocompatibility, photothermal conversion capabilities, chemical reactivity, and so on. At present, numerous studies have reported various structures and morphologies of PDA-functionalized capsules fabricated via diverse strategies, that have found applications across a broad spectrum of disciplines. However, there are few comprehensive and systematic reviews focusing on various preparation strategies of PDA-functionalized capsules with various structures. This paper systematically reviewed the preparation strategies and related applications of PDA-functionalized capsules. These strategies of PDA-functionalized capsules were discussed in detail from four parts including PDA-functionalized capsules based on hollow PDA, mesoporous PDA (MPDA), directly encapsulating emulsion, and surface modification of capsules. Then the review outlined the applications of PDA-functionalized capsules in biomedicine, energy, textiles, and the environment. Furthermore, this review summarized the current research findings on PDA-functionalized capsules and outlines their future development directions. Overall, we aim for this review to inspire researchers and offer valuable guidance for the synthesis and application of advanced PDA-functionalized capsules.

Photoinitiated Thiol-Ene Click Reaction for Preparation of Highly Adhesive and Mechanically Stable Silicone Coatings for Marine Antifouling and Anticorrosion

Marine biofouling and corrosion have become the main problems affecting the development of the marine industry. Silicone-based coatings have been widely used for antifouling and anticorrosion due to their low surface energy. However, the poor adhesion and low mechanical stability of these materials limit their application in complex marine environments. In this work, we presented a marine antifouling and anticorrosion coating named POSS-DMA@PDMS-TCM through photoinitiated thiol-ene click reaction combined with (mercaptopropyl) methylsiloxane dimethylsiloxane (PDMS-SH), dopamine methacrylamide (DMA), sulfhydryl-functionalized organosiloxanes (POSS-(SH)8), and N-(2,4,6-trichlorophenyl) maleimide (TCM). The POSS-DMA@PDMS-TCM coating exhibited strong stability and bonding ability both in air (2.17 MPa) and underwater (2.11 MPa) when the DMA content was 3 wt %. The high antibacterial (98.1% for Staphylococcus aureus and 99.5% for Escherichia coli) and antidiatom (94.5%) properties of the POSS-DMA@PDMS-TCM coatings have also been confirmed. Moreover, the POSS-DMA@PDMS-TCM coatings show excellent antifouling abilities in 120-day marine field tests, reducing fouling by 65.5% in comparison to the blank group. The coating also displayed superior anticorrosion performance with Ecorr values of -0.055 V, Icorr values of 7.67 × 10-6 , and Rp values of 3.10 × 105 Ω for Cu, which benefited from excellent chelating effect and liquid repellency. This study provides a novel strategy for the development of high-quality marine antifouling and anticorrosion coatings.

High-efficiency and economical uranium extraction from seawater with easily prepared supramolecular complexes

Developing effective adsorbents for uranium extraction from natural seawater is strategically significant for the sustainable fuel supply of nuclear energy. Herein, stable and low-cost supramolecular complexes (PA-bPEI complexes) were facilely constructed through the assembly of phytic acid and hyperbranched polyethyleneimine based on the multiple modes of electrostatic interaction and hydrogen bonding. The PA-bPEI complexes exhibited not only high uptake (841.7 mg g-1) and selectivity (uranium/vanadium selectivity = 84.1) toward uranium but also good antibacterial ability against biofouling. Mechanism analysis revealed that phosphate chelating groups and amine assistant groups coordinated the uranyl ions together with a high affinity. To be more suitable for practical applications, powdery PA-bPEI complexes were compounded with sodium alginate to fabricate various macroscopic adsorbents with engineered forms, which achieved an extraction capacity of 9.0 mg g-1 in natural seawater after 50 days of testing. Impressively, the estimated economic cost of the macroscopic adsorbent for uranium extraction from seawater ($96.5 ∼ 138.1 kg-1 uranium) was lower than that of all currently available uranium adsorbents. Due to their good uranium extraction performance and low economic cost, supramolecular complex-based adsorbents show great potential for industrial uranium extraction from seawater.

High mechanical property and hydrophilic electrospun poly amidoxime/poly acrylonitrile composite nanofibrous mats for extraction uranium from seawater

Seawater reserves about 4.5 billion tons of uranium, if properly extracted, could be a sustainable green energy resource for hundreds of years, alternating its limited terrestrial ore and reducing the CO2 emitted from fossil fuels. The current seawater uranium adsorbents suffer neither economically viable nor adsorption efficiency, requiring more development to harvest satisfactorily uranium from seawater. Amidoxime-based fibrous adsorbents are the most promising adsorbents of seawater uranium due to abundant chelating sites. However, they suffer from severe shrinkage and stiffness once they dry, losing porous architecture and mechanical properties. Herein, an economical and scalable two-nozzle electrospinning technology was applied to produce poly amidoxime nanofibers (PAO NFs) supported by Poly acrylonitrile nanofibers (PAN NFs) as composite PAO/PAN nanofibrous mats with high structure stability. These PAO/PAN mats, with rapid wettability and excellent mechanical strength, show promising uranium adsorption capacities of 369.8 mg/g at seawater pH level, much higher than PAO and PAN NFs. The uranium adsorption capacity of the PAO/PAN mat reached 5.16 mg/g after 7 days of circulating (10 ppm uranium) spiked natural seawater. Importantly, the composite mat maintained its fibrous structure after five adsorption-desorption cycles with more than 80 % of its adsorption capacity, confirming its recyclability and stability. Therefore, the composite PAO/PAN mat fulfills the basic requirements for effectively and economically trapping uranium from seawater, which could be a matrix for further development.

Efficient purification of low-level uranium-containing wastewater by polyamine/amidoxime synergistically reinforced fiber

The removal and recovery of uranium [U(VI)] from organic containing wastewater has been a challenging in radioactive wastewater purification. Here, we designed a polyamine/amidoxime polyacrylonitrile fiber (PAN-AO-A) with high removal efficiency, excellent selectivity, excellent organic resistance and low cost by combining the anti-organic properties of amidoxime polyacrylonitrile fiber (PAN-AO-A) with the high adsorption capacity of polyamine polyacrylonitrile fiber, which is used to extract U(VI) from low-level uranium-containing wastewater with high ammonia nitrogen and organic content. PAN-AO-A adsorbent with high grafting rate (86.52%), high adsorption capacity (qe = 618.8 mg g-1), and strong resistance to organics and impurity interference is achieved. The adsorption rate of U(VI) in both real organic and laundry wastewater containing uranium is as high as 99.7%, and the partition coefficients (Kd) are 7.61 × 105 mL g-1 and 9.16 × 106 mL g-1, respectively. The saturated adsorption capacity of PAN-AO-A in the continuous system solution can reach up to 505.5 mg g-1, and the concentration of U(VI) in the effluent is as low as 1 μg L-1. XPS analysis and Density functional theory (DFT) studies the coordination form between U(VI) and PAN-AO-A, where the most stable structure is η2-AO(UO2)(CO3)2. The -NH-/-NH2 and -C(NH2)N-OH groups of PAN-AO-A exhibit a synergistic complex effect in the U(VI) adsorption process. PAN-AO-A is a material with profound influence and limitless potential that can be used for wastewater containing U(VI) and organic matter.