Direct, Rapid, Facile Photochemical Method for Preparing Copper Nanoparticles and Copper Patterns

We develop a facile method for preparing copper nanoparticles and patterned surfaces with copper stripes by ultraviolet (UV) irradiation of a mixture solution containing a photoinitiator and a copper–amine coordination compound. The copper–amine compound is formed by adding diethanol amine to an ethanol solution of copper chloride. Under UV irradiation, free radicals are generated by photoinitiator decomposition. Meanwhile, the copper–amine coordination compound is rapidly reduced to copper particles because the formation of the copper–amine coordination compound prevents the production of insoluble cuprous chloride. Poly­(vinylpyrrolidone) is used as a capping agent to prevent the aggregation of the as-prepared copper nanoparticles. The capping agent increases the dispersion of copper nanoparticles in the ethanol solution and affects their size and morphology. Increasing the concentration of the copper–amine coordination compound to 0.1 M directly forms a patterned surface with copper stripes on the transparent substrate. This patterned surface is formed through the combination of the heterogeneous nucleation of copper nanoparticles and photolithography. We also investigate the mechanism of photoreduction by UV–vis spectroscopy and gas chromatography–mass spectrometry

Thermochromic Hydrogels with Adjustable Transition Behavior for Smart Windows

With the fast economic development and accelerating urbanization, more and more skyscrapers made entirely of concrete and glass are being constructed. To keep a comfortable indoor environment, massive energy for air conditioning or heating appliances is consumed. A huge amount of heat (>30%) is gained or released through glass windows. Using smart windows with the capability to modulate light is an effective way to reduce building energy consumption. Thermochromic hydrogel is one of the potential smart window materials due to its excellent thermal response, high radiation-blocking efficiency, cost-effectiveness, biocompatibility, and good uniformity. In this work, polyhydroxypropyl acrylate (PHPA) hydrogels with controllable lower critical solution temperature (LCST) were prepared by photopolymerization. The transition temperature and transition rate under “static transition” conditions were investigated. Unlike “static” conditions in which the transition temperature was not affected by the initial and final temperature and heating/cooling ramp, the transition temperature varied with the rate of temperature change under dynamic conditions. The “dynamic” transition temperature of the PHPA hydrogel gradually increased with the increase of the heating rate. It was the result of the movement of the molecular chains lagging behind the temperature change when the temperature change was too fast. The results of the solar irradiation experiment by filling PHPA hydrogels into double glazing windows showed that the indoor temperature was about 15 °C lower than that of ordinary glass windows, indicating that it can significantly reduce the energy consumption of air conditioning. In addition, a wide range of adjustable transition temperatures and fast optical response make PHPA hydrogels potentially applicable to smart windows

Customization of Supramolecular Hydrogels through One-Step Photopolymerization and Its Mechanism

Hydrogels used for different applications meet specific requirements of mechanical properties, leading to complicated material and process design. Here we report a simple one-step method for achieving a series of transparent hydrogels with highly tunable properties through free-radical photopolymerization (FRPP) of a single monomer, inspired by the fundamental mechanism of FRPP kinetics. The properties of poly-N-acryloyl 2-glycine (PNAG) hydrogels could be tailored within a range of 0.14 to 2.58 MPa tensile strength, 15 to 519 kPa Young’s modulus, and 33 to 2.8 × 103 g/g water-absorbing capacity by adjusting the polymer chain length and intermolecular interactions. The strongest PNAG hydrogel, with a tensile strength of 2.58 MPa, could be stretched to 14 times its original length and showed high elasticity with low hysteresis under cyclic loading at low deformation. More intriguingly, the photochemical decomposition rate of photoinitiator 1173 under UV-LED (365 nm) and the internal interactions of PNAG hydrogels were found to be temperature-dependent, which may offer a promising supplement to the temperature effect theory in FRPP. This work not only presents a new perspective for the design of hydrogels for a specific application but also paves the way for more extensive cooperation between FRPP and other preparation methods

Decomposable Polyvinyl Alcohol-Based Super-Hydrophobic Three-Dimensional Porous Material for Effective Water/Oil Separation

The development of the oil industry brings the critical problem of ocean pollution by oil spill or fossil fuels. The use of materials for water/oil separation is one of the effective approaches to solve this crisis. Polyvinyl alcohol (PVA) has been used  to prepare water/oil separation materials. Currently, glutaraldehyde has been employed as the cross-linking agent, which is well known to be toxic and environmentally unfriendly. Moreover, it is difficult to deal with the disposal of the Across-linked material. Here, we propose a strategy of fabricating macroporous material which was prepared by PVA and sodium silicate (Na2SiO3) in aqueous solution. Following through with the one-step method of sol–gel reaction of hydroxyl groups with trimethoxy­(octadecyl)­silane, the low surface energy substance was grafted on the macroporous material and a super-hydrophobic macroporous membrane for water/oil separation was prepared. As oil sorbent, the as-prepared dried super-hydrophobic PVA/Na2SiO3 porous materials (PSD6S) have the adsorption capacity of 1.8–7.0 g/g for oil uptake, which depends on the type of oil liquid. Typically, the separation efficiency of this material could reach more than 99% even after 10 times of use without the help of ambient pressure. It is noteworthy that the as-prepared samples could be easily decomposable and dissolvable completely in acidic medium at a rapid rate

A Facile Method to Prepare Molecularly Imprinted Layer-by-Layer Nanostructured Multilayers Using Postinfiltration and a Subsequent Photo-Cross-Linking Strategy

In this paper, we have demonstrated a facile strategy to prepare molecularly imprinted layer-by-layer nanostructured films. This strategy has circumvented the requirement of using photocross-linkable polymers, which suffered from tedious synthetic processes in the construction of surface molecular imprinting in layer-by-layer (SMI-LbL) devices. The described SMI-LbL device was constructed by employing the traditional construction procedures of LbL systems, followed by the postinfiltration of bifunctional photosensitive cross-linking agent 4,4′-diazostilbene-2,2′-disulfonic acid disodium salt into the prepared multilayers, and subsequent photocross-linking. A robust SMI-LbL device with high fatigue-resistance was achieved. The preparation conditions have been optimized to achieve repeated unloading and rebinding of the targeting molecule with high fidelity. The combination of templating and cross-linking is the core factor to achieve high fidelity and high efficiency of the SMI-LbL device

Decomposable Polyvinyl Alcohol-Based Super-Hydrophobic Three-Dimensional Porous Material for Effective Water/Oil Separation

The development of the oil industry brings the critical problem of ocean pollution by oil spill or fossil fuels. The use of materials for water/oil separation is one of the effective approaches to solve this crisis. Polyvinyl alcohol (PVA) has been used  to prepare water/oil separation materials. Currently, glutaraldehyde has been employed as the cross-linking agent, which is well known to be toxic and environmentally unfriendly. Moreover, it is difficult to deal with the disposal of the Across-linked material. Here, we propose a strategy of fabricating macroporous material which was prepared by PVA and sodium silicate (Na2SiO3) in aqueous solution. Following through with the one-step method of sol–gel reaction of hydroxyl groups with trimethoxy­(octadecyl)­silane, the low surface energy substance was grafted on the macroporous material and a super-hydrophobic macroporous membrane for water/oil separation was prepared. As oil sorbent, the as-prepared dried super-hydrophobic PVA/Na2SiO3 porous materials (PSD6S) have the adsorption capacity of 1.8–7.0 g/g for oil uptake, which depends on the type of oil liquid. Typically, the separation efficiency of this material could reach more than 99% even after 10 times of use without the help of ambient pressure. It is noteworthy that the as-prepared samples could be easily decomposable and dissolvable completely in acidic medium at a rapid rate

Decomposable Polyvinyl Alcohol-Based Super-Hydrophobic Three-Dimensional Porous Material for Effective Water/Oil Separation

The development of the oil industry brings the critical problem of ocean pollution by oil spill or fossil fuels. The use of materials for water/oil separation is one of the effective approaches to solve this crisis. Polyvinyl alcohol (PVA) has been used  to prepare water/oil separation materials. Currently, glutaraldehyde has been employed as the cross-linking agent, which is well known to be toxic and environmentally unfriendly. Moreover, it is difficult to deal with the disposal of the Across-linked material. Here, we propose a strategy of fabricating macroporous material which was prepared by PVA and sodium silicate (Na2SiO3) in aqueous solution. Following through with the one-step method of sol–gel reaction of hydroxyl groups with trimethoxy­(octadecyl)­silane, the low surface energy substance was grafted on the macroporous material and a super-hydrophobic macroporous membrane for water/oil separation was prepared. As oil sorbent, the as-prepared dried super-hydrophobic PVA/Na2SiO3 porous materials (PSD6S) have the adsorption capacity of 1.8–7.0 g/g for oil uptake, which depends on the type of oil liquid. Typically, the separation efficiency of this material could reach more than 99% even after 10 times of use without the help of ambient pressure. It is noteworthy that the as-prepared samples could be easily decomposable and dissolvable completely in acidic medium at a rapid rate

Small-World Brain Network and Dynamic Functional Distribution in Patients with Subcortical Vascular Cognitive Impairment

<div><p>To investigate the topological properties of the functional connectivity and their relationships with cognition impairment in subcortical vascular cognitive impairment (SVCI) patients, resting-state fMRI and graph theory approaches were employed in 23 SVCI patients and 20 healthy controls. Functional connectivity between 90 brain regions was estimated using bivariate correlation analysis and thresholded to construct a set of undirected graphs. Moreover, all of them were subjected to a battery of cognitive assessment, and the correlations between graph metrics and cognitive performance were further analyzed. Our results are as follows: functional brain networks of both SVCI patients and controls showed small-world attributes over a range of thresholds(0.15≤sparsity≤0.40). However, global topological organization of the functional brain networks in SVCI was significantly disrupted, as indicated by reduced global and local efficiency, clustering coefficients and increased characteristic path lengths relative to normal subjects. The decreased activity areas in SVCI predominantly targeted in the frontal-temporal lobes, while subcortical regions showed increased topological properties, which are suspected to compensate for the inefficiency of the functional network. We also demonstrated that altered brain network properties in SVCI are closely correlated with general cognitive and praxis dysfunction. The disruption of whole-brain topological organization of the functional connectome provides insight into the functional changes in the human brain in SVCI.</p></div