Boosted Interfacial Polarization from the Multidimensional Core–Shell–Flat Heterostructure CNP@PDA@GO/rGO for Enhanced Microwave Absorption

Heterogeneous structures have attracted extensive attention in the area of microwave absorption because they can promote interfacial polarization and thus enhance microwave absorption. Many efforts have been made in this field; however, challenges remain in terms of the absorber impedance matching and electromagnetic (EM) wave reflectivity. Herein, a multidimensional core–shell–flat heterostructure is proposed to build a kind of EM wave absorbers with both dielectric loss and magnetic loss. Polydopamine (PDA) is coated on the surface of nanoscale carbonyl nickel powder (CNP) to obtain the core–shell structure of CNP@PDA nanoparticles, and then, the CNP@PDA nanoparticles are grafted around graphene oxide (GO)/reduced GO (rGO) or sandwiched between the layers of GO/rGO to form a core–shell–flat heterostructure. Two-dimensional GO/rGO and three-dimensional PDA can modulate the impedance matching of nano-CNP and enhance the interfacial polarization of the absorber. The reflection loss of ternary CNP@PDA@GO/rGO is better than that of binary CNP@PDA or CNP@GO due to the interfacial polarization and multiple interfacial scattering of the heterostructure. The minimum reflection loss can reach −70.7 dB with a thickness of 2.5 mm, while the efficient absorption bandwidth (≤−10 dB) can achieve 8.5 GHz. The heterojunction contacts constructed by CNP–PDA and PDA–GO/rGO contribute to the enhanced polarization loss and interfacial reflection loss. The mechanism of excellent EM wave absorption is explained by enhanced interfacial polarization, interface scattering, and adjusted impedance matching. These results pave the way to fabricate high-performance EM wave absorption materials with a controlled multidimensional morphology and balanced impedance matching

Zwitterion-Modified Nanogel Responding to Temperature and Ionic Strength: A Dissipative Particle Dynamics Simulation

The self-assembly and stimuli-responsive properties of nanogel poly(n-isopropylacrylamide) (p(NIPAm)) and zwitterion-modified nanogel poly(n-isopropylacrylamide-co-sulfobetainemethacrylate) (p(NIPAm-co-SBMA)) were explored by dissipative particle dynamics simulations. Simulation results reveal that for both types of nanogel, it is beneficial to form spherical nanogels at polymer concentrations of 5–10%. When the chain length (L) elongates from 10 to 40, the sizes of the nanogels enlarge. As for the p(NIPAm) nanogel, it shows thermoresponsiveness; when it switches to the hydrophilic state, the nanogel swells, and vice versa. The zwitterion-modified nanogel p(NIPAm-co-SBMA) possesses thermoresponsiveness and ionic strength responsiveness concurrently. At 293 K, both hydrophilic p(NIPAm) and superhydrophilic polysulfobetaine methacrylate (pSBMA) could appear on the outer surface of the nanogel; however, at 318 K, superhydrophilic pSBMA is on the outer surface to cover the hydrophobic p(NIPAm) core. As the temperature rises, the nanogel shrinks and remains antifouling all through. The salt-responsive property can be reflected by the nanogel size; the volumes of the nanogels in saline systems are larger than those in salt-free systems as the ionic condition inhibits the shrinkage of the zwitterionic pSBMA. This work exhibits the temperature-responsive and salt-responsive behavior of zwitterion-modified-pNIPAm nanogels at the molecular level and provides guidance in antifouling nanogel design

Zwitterion-Modified Nanogel Responding to Temperature and Ionic Strength: A Dissipative Particle Dynamics Simulation

The self-assembly and stimuli-responsive properties of nanogel poly(n-isopropylacrylamide) (p(NIPAm)) and zwitterion-modified nanogel poly(n-isopropylacrylamide-co-sulfobetainemethacrylate) (p(NIPAm-co-SBMA)) were explored by dissipative particle dynamics simulations. Simulation results reveal that for both types of nanogel, it is beneficial to form spherical nanogels at polymer concentrations of 5–10%. When the chain length (L) elongates from 10 to 40, the sizes of the nanogels enlarge. As for the p(NIPAm) nanogel, it shows thermoresponsiveness; when it switches to the hydrophilic state, the nanogel swells, and vice versa. The zwitterion-modified nanogel p(NIPAm-co-SBMA) possesses thermoresponsiveness and ionic strength responsiveness concurrently. At 293 K, both hydrophilic p(NIPAm) and superhydrophilic polysulfobetaine methacrylate (pSBMA) could appear on the outer surface of the nanogel; however, at 318 K, superhydrophilic pSBMA is on the outer surface to cover the hydrophobic p(NIPAm) core. As the temperature rises, the nanogel shrinks and remains antifouling all through. The salt-responsive property can be reflected by the nanogel size; the volumes of the nanogels in saline systems are larger than those in salt-free systems as the ionic condition inhibits the shrinkage of the zwitterionic pSBMA. This work exhibits the temperature-responsive and salt-responsive behavior of zwitterion-modified-pNIPAm nanogels at the molecular level and provides guidance in antifouling nanogel design

Zwitterion-Modified Nanogel Responding to Temperature and Ionic Strength: A Dissipative Particle Dynamics Simulation

The self-assembly and stimuli-responsive properties of nanogel poly(n-isopropylacrylamide) (p(NIPAm)) and zwitterion-modified nanogel poly(n-isopropylacrylamide-co-sulfobetainemethacrylate) (p(NIPAm-co-SBMA)) were explored by dissipative particle dynamics simulations. Simulation results reveal that for both types of nanogel, it is beneficial to form spherical nanogels at polymer concentrations of 5–10%. When the chain length (L) elongates from 10 to 40, the sizes of the nanogels enlarge. As for the p(NIPAm) nanogel, it shows thermoresponsiveness; when it switches to the hydrophilic state, the nanogel swells, and vice versa. The zwitterion-modified nanogel p(NIPAm-co-SBMA) possesses thermoresponsiveness and ionic strength responsiveness concurrently. At 293 K, both hydrophilic p(NIPAm) and superhydrophilic polysulfobetaine methacrylate (pSBMA) could appear on the outer surface of the nanogel; however, at 318 K, superhydrophilic pSBMA is on the outer surface to cover the hydrophobic p(NIPAm) core. As the temperature rises, the nanogel shrinks and remains antifouling all through. The salt-responsive property can be reflected by the nanogel size; the volumes of the nanogels in saline systems are larger than those in salt-free systems as the ionic condition inhibits the shrinkage of the zwitterionic pSBMA. This work exhibits the temperature-responsive and salt-responsive behavior of zwitterion-modified-pNIPAm nanogels at the molecular level and provides guidance in antifouling nanogel design

Zwitterion-Modified Nanogel Responding to Temperature and Ionic Strength: A Dissipative Particle Dynamics Simulation

The self-assembly and stimuli-responsive properties of nanogel poly(n-isopropylacrylamide) (p(NIPAm)) and zwitterion-modified nanogel poly(n-isopropylacrylamide-co-sulfobetainemethacrylate) (p(NIPAm-co-SBMA)) were explored by dissipative particle dynamics simulations. Simulation results reveal that for both types of nanogel, it is beneficial to form spherical nanogels at polymer concentrations of 5–10%. When the chain length (L) elongates from 10 to 40, the sizes of the nanogels enlarge. As for the p(NIPAm) nanogel, it shows thermoresponsiveness; when it switches to the hydrophilic state, the nanogel swells, and vice versa. The zwitterion-modified nanogel p(NIPAm-co-SBMA) possesses thermoresponsiveness and ionic strength responsiveness concurrently. At 293 K, both hydrophilic p(NIPAm) and superhydrophilic polysulfobetaine methacrylate (pSBMA) could appear on the outer surface of the nanogel; however, at 318 K, superhydrophilic pSBMA is on the outer surface to cover the hydrophobic p(NIPAm) core. As the temperature rises, the nanogel shrinks and remains antifouling all through. The salt-responsive property can be reflected by the nanogel size; the volumes of the nanogels in saline systems are larger than those in salt-free systems as the ionic condition inhibits the shrinkage of the zwitterionic pSBMA. This work exhibits the temperature-responsive and salt-responsive behavior of zwitterion-modified-pNIPAm nanogels at the molecular level and provides guidance in antifouling nanogel design

Highly Flexible, Freezing-Resistant, Anisotropically Conductive Sandwich-Shaped Composite Hydrogels for Strain Sensors

Anisotropically conductive hydrogels have promising applications in artificial intelligence and wearable flexible electronics. However, for conductive hydrogels, the integration of comprehensive properties, such as high electrical conductivity, strong moisture retention, and high mechanical properties, is very important. In this article, sandwich-shaped anisotropically conductive hydrogels were constructed with a conductivity of up to 1.5 S/m. The difference in conductivity along the different directions is about a factor of 6. The formation of dynamic coordination bonding enhances the cross-linked network between poly(acrylic acid) and Nd3+, which causes the hydrogels to have excellent self-healing properties and fatigue resistance, with a self-healing efficiency of up to 90%. The middle layer of the hydrogels is compounded with nanographene, which cuases the hydrogels to have good mechanical properties, such as ultrastretchability (∼1930%) and high strength (∼0.7 MPa). The binary solvent consisting of glycerin and water gives the hydrogels an excellent moisturizing and antifreezing function. It maintains good flexibility and conductivity even at −18 °C. Based on the rapid response and high sensitivity, the sandwich-shaped hydrogel strain sensors can detect human motion (such as knuckle motion, wrist movement, etc.), showing great application potential in flexible sensors

Multifunctional Nanoplatform for Mild Microwave-Enhanced Thermal, Antioxidative, and Chemotherapeutic Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is usually associated with excessive proliferation of M1-type proinflammatory macrophages, resulting in severe hypoxia and excess reactive oxygen species (ROS) in the joint cavity. Inhibiting M1-type proinflammatory macrophages and/or repolarizing them into M2 phenotype anti-inflammatory cells by alleviating hypoxia and scavenging ROS could be a promising strategy for RA treatment. In this work, a microwave-sensitive metal–organic framework of UiO-66-NH2 is constructed for coating a nanoenzyme of cerium oxide (CeO2) and loading with the drug celastrol (Cel) to give UiO-66-NH2/CeO2/Cel, which is ultimately wrapped with hyaluronic acid (HA) to form a nanocomposite UiO-66-NH2/CeO2/Cel@HA (UCCH). With the microwave-susceptible properties of UiO-66-NH2, the thermal effect of microwaves can eliminate the excessive proliferation of inflammatory cells. In addition, superoxide-like and catalase-like activities originating from CeO2 in UCCH are boosted to scavenge ROS and accelerate the decomposition of H2O2 to produce O2 under microwave irradiation. The nonthermal effect of microwaves could synergistically promote the repolarization of M1-type macrophages into the M2 phenotype. Accompanied by the release of the anti-RA chemotherapeutic drug Cel, UCCH can efficiently ameliorate RA in vitro and in vivo through microwave-enhanced multisynergistic effects. This strategy could inspire the design of other multisynergistic platforms enhanced by microwaves to exploit new treatment modalities in RA therapies