Rational design and preparation of bioinspired polydopamine (PDA)-based synthetic melanin hybrid materials with well-controlled morphologies and improved properties face a grand challenge at the ...current situation. Herein, we report the facile fabrication of photocatalytic CdS@PDA patchy nanoparticles with tunable inorganic patchy densities via different Cd2+-loaded PDA precursors. Both of “postdoping” and “predoping” strategies can be used to fabricate CdS@PDA hybrid NPs with distinct CdS patchy densities, which could further induce distinct physical properties and catalytic behaviors. Those resulting functional nanocomposites exhibited significantly enhanced photoactivity and photostability toward the catalytic degradation of methylene blue under visible light irradiation. We believe that the excellent adsorption, redox potential, and free-radical scavenging properties of PDA substrates could provide the outstanding photoactivity and photostability for CdS photocatalytic reaction. This work could inspire more kinds of synthetic melanin-based functional hybrids for stable, efficient, and sustainable photocatalysis.
Rubber composites with excellent radiation shielding and flexibility are extremely important to personal protective equipments (PPEs) for protecting workers from radiation hazards, especially for ...mixed radiations. It is, however, challenging to achieve uniform dispersion of fillers and good compatibility of the interfaces in highly‐filled rubber composites that are closely related to their physical properties. In this article, lead borate@polydopamine (PBO@PDA) core–shell particles are chemically bonded with silicone rubber (SR) for co‐shielding of neutron and γ‐rays. Uniform dispersion of the core–shell particles and good compatibility of the interfaces give rise to enhanced flexibility of the rubber composites. Particularly, the SR composite with 40 wt% PBO particles displays increases of 106% in elongation at break and 490% in tensile strength to neat SR. Furthermore, the mass attenuation coefficient of γ‐rays (105 KeV) reaches 2.35 and the thermal neutron absorption rate (0.025 eV) of is 76.9%. This work takes into account the balance between radiation shielding and flexibility of rubber composites, which provides a facile strategy to fabricate excellent integrated properties of flexible materials for shielding mixed neutron and γ‐rays.
Lead borate micro–nano particles chemically bonded with silicone rubber are used to coordinately shield thermal neutrons and gamma rays.
Flexible materials with excellent radiation shielding and flexibility are essential to the personal protective equipments (PPEs) for protecting workers from nuclear radiations. However, it is an ...enormous challenge to obtain the desired materials since high loading filler in polymer nanocomposites usually promotes radiation shielding while restrains its flexibility. Here, a facile “thiol‐ene click” means is applied to chemically bond high loading boron nitride (BN) nanoparticles with silicone rubber (SR) in SR/BN nanocomposites for thermal neutron shielding. Uniform dispersion of BN nanoparticles and good compatibility of interfaces in the nanocomposites with high loading filler lead to increased flexibility instead of decrease. In particular, the nanocomposite with 40 wt% BN displays 911% of elongation at break that is about 50% enhancement to that of neat SR. Furthermore, higher loading BN in the nanocomposites means better thermal neutron shielding. Namely, enhanced thermal neutron shielding and flexibility is achieved at SR/BN nanocomposite with 40 wt% BN. The present work provides a facile strategy towards superior integrated performance of flexible materials for radiation shielding, such as wearable devices.
Chemically bonding BN nanoparticles with silicone rubber contributes to good interfacial compatibility in highly‐filled polymer nanocomposites, leading to enhanced radiation shielding and flexibility.
Incorporating ultralow loading of nanoparticles into polymers has realized increases in dielectric constant and breakdown strength for excellent energy storage. However, there are still a series of ...tough issues to be dealt with, such as organic solvent uses, which face enormous challenges in scalable preparation. Here, a new strategy of dual in situ synthesis is proposed, namely polymerization of polyethylene terephthalate (PET) synchronizes with growth of calcium borate nanoparticles, making polyester nanocomposites from monomers directly. Importantly, this route is free of organic solvents and surface modification of nanoparticles, which is readily accessible to scalable synthesis of polyester nanocomposites. Meanwhile, uniform dispersion of as ultralow as 0.1 wt% nanoparticles and intense bonding at interfaces have been observed. Furthermore, the PET-based nanocomposite displays obvious increases in both dielectric constant and breakdown strength as compared to the neat PET. Its maximum discharged energy density reaches 15 J cm
at 690 MV m
and power density attains 218 MW cm
under 150 Ω resistance at 300 MV m
, which is far superior to the current dielectric polymers that can be produced at large scales. This work presents a scalable, safe, low-cost, and environment-friendly route toward polymer nanocomposites with superior capacitive performance.
Melanin-inspired polymers are currently the focus of growing interest for a wide range of applications ranging from energy to biomedical area. Whilst researchers have made numerous attempts to ...prepare and utilize polydopamine nanoparticles (PDA NPs), they have made limited progress in developing and discovering another typical functional mimic of natural melanin, poly (levodopa) (P(L-DOPA)) NPs, probably due to the lack of facile synthetic strategies towards satisfactory structural and functional control of melanin-like NPs. Herein, we reported a one-pot preparation method towards P(L-DOPA) NPs with good yields and controllable size/property in an aqueous solution assisted by various metal ions (
i.e.
, Ni(II), Mg(II), Ca(II), Fe(III), Mn(II), Co (II), Zn(II) and Cd(II)). Interestingly, the resulting P(L-DOPA) NPs exhibited enhanced light absorption and photothermal behaviors compared with well-established PDA NPs, which can be employed to further fabricate kinds of photothermal composite actuators with promising performances such as folding, switching, and forward-moving. This study offers a facile and robust way to synthesize new synthetic melanins beyond PDA, and facilitates further functional discovery and evolution of melanin-inspired polymers and composites.
Selecting high molecular weight has become a quite popular approach for effective tuning of more shish-kebabs in semi-crystalline polymers. However, here, an unusual dependence of shish-kebabs on ...molecular weight of high-density polyethylene (HDPE) is found under the injection molding with a secondary flow. Characterization with electron microscope and X-ray scattering of the crystal structures reveals that the richest shish-kebabs develop in the HDPE with medium high molecular weight (HMW) chains rather than in the HDPE with more HMW chains. Both macroscopic scales (fluid behaviors related to the intensity of flow) and molecular scales (rheological properties related to orientation and relaxation) need to be overall considered and a physical model has been proposed to explain how the coupling between the chain architectures and the secondary flow field contributes to the unusual phenomenon. The factors, such as molecular parameters, interfaces between dispersed phase, and matrix as well as the properties of filler, profoundly influence both the two scales, which can be employed to tune the morphology related to physical properties. These significant results provide a simple but effective morphology control technique under a secondary flow field.
A mass of stretched molecular chains in the entire thickness direction of gas‐assisted injection molding (GAIM) composites is induced due to the redistribution and amplification of the shear flow ...caused by the introduction of polycarbonate (PC) microfibril under intense shear stress. In the vicinity of the PC microfibrils, stretched chains are either absorbed by PC microfibrils with a large diameter to form a transcrystallinity, or captured by ultrafine PC microfibrils to firstly form shish nuclei and finally form hybrid shish‐kebab structures. Typical shish‐kebab superstructures are formed in the zone with the absence of PC microfibrils. In summary, multiform crystalline superstructures across the thickness direction are successfully obtained by the GAIM. Thus, this work can open a new way for the preparation of high‐performance polymer composites in industrial processing.
A mass of stretched molecular chains are induced in secondary shear flow. In the vicinity of the polycarbonate (PC) microfibrils, stretched chains are either absorbed by PC microfibrils with a large diameter to form a transcrystallinity, or captured by ultrafine PC microfibrils to finally form hybrid shish‐kebab structures. Typical shish‐kebab superstructures are formed in the zone with the absence of PC microfibrils.
One effective measure of radioactive material purification is the use of strippable decontaminants, which effectively coat the pollutant, capture suspended particles in the air, and deposit them onto ...the surfaces of objects. However, there are some shortcomings in terms of film formation and peelability, such as a brittle coating and poor peelability. Therefore, in order to meet future military and emergency needs, this research investigated the influencing factors in the process of surface strippable decontamination. Experiments included tests for wettability, potential, particle size, strippable performance, tensile performance, ultraviolet transmittance reflectance, and film formation as well as image analysis of photomicrographs from an optical microscope system. These experiments indicate that the strippable decontaminant is a viable means of contamination removal.
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