Enhancing Methane Removal Efficiency of ZrMnFe Alloy by Partial Replacement of Fe with Co.

High-purity hydrogen is extensively employed in chemical vapor deposition, and the existence of methane impurity significantly impacts the device performance. Therefore, it is necessary to purify hydrogen to remove methane. The ZrMnFe getter commonly used in the industry reacts with methane at a temperature as high as 700 ∘C, and the removal depth is not sufficient. To overcome these limitations, Co partially substitutes Fe in the ZrMnFe alloy. The alloy was prepared by suspension induction melting method, and was characterized by means of XRD, ICP, SEM and XPS. The concentration of methane at the outlet was detected by gas chromatography to characterize the hydrogen purification performance of the alloy. The removal effect of the alloy on methane in hydrogen increases first and then decreases with the increase in substitution amount, and increases with the increase in temperature. Specifically, the ZrMnFe0.7Co0.3 alloy reduces methane levels in hydrogen from 10 ppm to 0.215 ppm at 500 ∘C. ZrMnFe0.7Co0.3 alloy can remove 50 ppm of methane in helium to less than 0.01 ppm at 450 ∘C, demonstrating its excellent methane reactivity. Moreover, Co substitution reduces the formation energy barrier of ZrC, and Co in the electron-rich state demonstrates superior catalytic activity for methane decomposition.

Thermoresponsive Water-in-Oil-in-Water Pickering Double Emulsions Stabilized with Biodegradable and Semicrystalline Poly(ethylene glycol)-b-poly(ε-caprolactone-co-δ-valerolactone) Diblock Copolymer Micelles for Controlled Release.

Water-in-oil-in-water (W/O/W) Pickering double emulsions are promising materials for the construction of carriers for water-soluble and oil-soluble molecules or drug delivery systems if the contradictive trade-off between their extreme stability and controlled release properties can be resolved. In this study, biodegradable and biocompatible poly(ethylene glycol)-b-poly(ε-caprolactone-co-δ-valerolactone) (PEG-b-PCVL) diblock copolymers with predesigned hydrophilic to hydrophobic block length ratios and nearly identical ε-caprolactone/δ-valerolactone molar ratio (8/2), were synthesized by ring-opening copolymerization. Then, they self-assembled to create semicrystalline micelles. The melting points of PEG-b-PCVL copolymers and their lyophilized micelles were within a physiological range of temperatures, as determined by differential scanning calorimetry. Water contact angle measurements provided evidence that the surface wettability of PEG-b-PCVL micelles could be tuned by the PCVL block mass fractions or temperature stimulus. Such PEG-b-PCVL micelles were employed as a single particulate stabilizer to develop Pickering double emulsions through a one-step emulsification technique. W/O/W Pickering double emulsions could be generated using relatively hydrophobic PEG-b-PCVL micelles with high mass fractions (exceeding about 89%) of PCVL blocks, and they displayed excellent long-term physical stabilities at room temperature. However, the Pickering double emulsions underwent a rapid microstructural transition into simple oil-in-water Pickering emulsions instead of complete demulsification at elevated temperature (37 °C), which was attributed to the hydrophilicity of micelles enhanced when the core-forming PCVL melted realized by temperature stimulus. Consequently, such W/O/W Pickering double emulsions stabilized solely with semicrystalline PEG-b-PCVL micelles exhibit thermal responsiveness, enabling them to release vitamin B12 encapsulated within the internal aqueous phase rapidly.

Microstructurally tunable pickering emulsions stabilized by poly(ethylene glycol)-b-poly(ε-caprolactone) diblock biodegradable copolymer micelles with predesigned polymer architecture.

Poly(ethylene glycol)-b-poly(ε-caprolactone) diblock copolymers (PEG-b-PCL) with predesigned hydrophilic/hydrophobic block length ratios have been synthesized and self-assembled to form micelles, then used to emulsify medium-chain triglycerides with an aqueous phase. The morphologies and sizes of PEG-b-PCL copolymer micelles have been characterized by transmission electron microscopy and dynamic light scattering. Interfacial tension testing between micellar dispersions and oil, combined with water contact angle measurements, have been performed to assess the ability of these micelles to adjust interfacial tension and micellar hydrophobicity, respectively. Relationship between the wettability of PEG-b-PCL copolymer micelles and their emulsification properties has been proved through phase diagram, optical microscopic observation, droplet sizes evolution and phase separation behavior of Pickering emulsion samples. Results show that both oil-in-water and water-in-oil Pickering emulsions, as well as water-in-oil-in-water (W/O/W) double-Pickering emulsions, may be controllably prepared through one-step homogenization. Double microstructure of W/O/W Pickering emulsion has proved to be extremely stable during long-term storage.

Synergic influences of network topologies and associative interactions on the microstructures and bulk performances of hydrogels.

Revealing the relationship between network topologies and mechanical properties of hydrogels is fundamental yet challenging in the design of tough soft materials. Here, we report a series of hydrogels using N-isopropyl acrylamide (NIPAm) and acrylic acid (AAc) as the basic units to form a single network of the copolymer, a semi-interpenetrated network of two homopolymers, and a grafted network with homopolymer chains anchored on another homopolymer network, to investigate the influence of network architectures on the mechanical properties and thermal responses of the gels. We found that the properties of the gels are also significantly influenced by the formation of hydrogen bonds between poly(N-isopropyl acrylamide) (PNIPAm) and poly(acrylic acid) (PAAc) segments. The gels with the single network of poly(NIPAm-co-AAc) are mechanically weak due to the low efficiency for forming robust hydrogen bonds, while micro-segregated domains are formed in the hydrogels with a semi-interpenetrated network structure due to the formation of inter-chain hydrogen bonds that favors energy dissipation and toughening of the gels. On the other hand, dense hydrogen bonds form between the grafted PNIPAm chains and the PAAc network, resulting in nano-segregated domains and excellent mechanical properties of the gels. The hydrogels with the grafted network structure exhibit a more repeatable response to temperature than those with the semi-interpenetrated network structure due to the relatively stable hydrogen-bond network. The comparison of the mechanical properties and thermal stability of the hydrogels with the same composition but different topological networks should be informative for engineering hydrogel properties or functions by tailoring the network structures.

Bioinspired, Recyclable, Stretchable Hydrogel with Boundary Ultralubrication.

Although hydrogels exhibit excellent low frictional behavior, their friction coefficients cannot meet the requirements for biology, especially at low sliding velocities. Inspired by the natural lubrication mechanism from animals, plants, or even microorganisms, a nonionic surfactant, Tween 80, was introduced into a biofriendly poly(vinyl alcohol) (PVA) hydrogel to construct a composite hydrogel with ultralubrication. Such a combination endows PVA hydrogels with an ultralow coefficient of friction (10-3 to 10-4) under an extremely low sliding velocity (0.01 mm/s). Tween 80 micelles and aggregates, together with hydrophobic molds, induce rough surfaces and high carbon contents on the surface of the hydrogel, promoting excellent lubrication behavior of the composite hydrogel. In addition to the desirable lubrication, this environmentally friendly composite hydrogel also exhibited excellent flexibility at subzero temperatures, tensile properties, and good recyclability. Additionally, the method of introducing Tween 80 into hydrogels to reduce friction is also effective in chemically crosslinked double-network hydrogels.

Programmable Deformations of Biomimetic Composite Hydrogels Embedded with Printed Fibers.

Shape deformations are prevalent in nature, which are closely related to the heterogeneous structures with a feature of fibrous elements embedded in a matrix. The microfibers with specific orientations act as either passive geometrical constraints in an active matrix or active elements in a passive matrix, which generate programmed internal stresses and drive shape morphing under external stimuli. Morphing materials can be designed in a biomimetic way, yet it is challenging to fabricate composite hydrogels with well-distributed fibers by a facile strategy. Here, we demonstrate the fabrication of microfiber-embedded hydrogels facilitated by the extrusion-based printing technology. Programmed deformations are achieved in these hydrogels with microfibers distributed in the upper and/or bottom layers of the gel matrix. Under external stimuli, the microfibers and the gel matrix have different responses that produce internal stresses and result in programmable deformations of the composite gel. Multiple shape transformations are realized in the hydrogel by embedding multiple types of responsive microfibers in the passive or active matrix, which is fabricated with the assistance of multinozzle printing. A soft hook is designed to show the capacity of the composite hydrogel to hold and move an object in a saline solution. This facile and versatile strategy provides an alternative way to prepare biomimetic hydrogels with potential applications in biomedical devices, flexible electronics, and soft robots.

A γ-cyclodextrin-based metal-organic framework embedded with graphene quantum dots and modified with PEGMA via SI-ATRP for anticancer drug delivery and therapy.

The γ-cyclodextrin-based metal-organic framework (γ-CD-MOF) composite was designed and prepared toward targeted anticancer drug delivery and cancer therapy. Large amounts of graphene quantum dots (GQDs) were embedded in the γ-CD-MOF matrix (denoted as GQDs@γ-CD-MOF) to endow the γ-CD-MOF with strong fluorescence, which was then modified by pH responsive poly(ethyleneglycol)dimethacrylate (PEGMA) through surface initiated atom transfer radical polymerization (SI-ATRP) to fabricate the PEGMA@GQDs@γ-CD-MOF composite. Then, the cancer cell-targeted probe was obtained by immobilizing the AS1411 aptamer over it (denoted as AS1411@PEGMA@GQDs@γ-CD-MOF) and it exhibits pH-responsive release function and excellent targeting ability. Large amounts of antitumour drug, doxorubicin hydrochloride (DOX), could be encapsulated within this composite due to the chemical-rich functionality, and the resultant pH-responsive DOX delivery system (denoted as DOX/AS1411@PEGMA@GQDs@γ-CD-MOF) displayed a higher DOX loading of 89.1% with sustained release than the pristine γ-CD-MOF and GQDs@γ-CD-MOF. The targeting specificity investigation revealed that this DOX delivery system was effectively internalized via receptor mediated endocytosis with high selectivity. The in vivo antitumour study with tumour-bearing mice illustrated that the tumour growth can be effectively suppressed and partially ablated with negligible side effects after treatments. Therefore, the proposed AS1411@PEGMA@GQD@γ-CD-MOF composite is promising for effective DOX delivery and tumour growth inhibition both in vitro and in vivo, showing great potential for anticancer therapy.

A multiple aptasensor for ultrasensitive detection of miRNAs by using covalent-organic framework nanowire as platform and shell-encoded gold nanoparticles as signal labels.

We report herein a novel multiple electrochemical aptasensor based on covalent-organic framework (COF) for sensitive and simultaneous detection of miRNA 155 and miRNA 122, by using shell-encoded gold nanoparticles (Au NPs) as signal labels (AgNCs@AuNPs and Cu2O@AuNPs, respectively, NCs = nanoclusters). A new COF nanowire was synthesized via condensation polymerization of 1,3,6,8-tetra(4-carboxylphenyl)pyrene and melamine (represented by TBAPy-MA-COF-COOH) for multiple aptasensor fabrication. The nanowire was then used as a platform for anchoring single-strand DNA (ssDNA), which was hybridized with the complementary aptamer (cApt) probes of miRNA 155 and miRNA 122. AgNCs@AuNPs and Cu2O@AuNPs modified with cApts show separated differential pulse voltammetry (DPV) peaks at 0.08 and -0.1 V, respectively. The signal labels immobilized with cApts were released from the hybridized DNA complex and bound to their corresponding targets when contacting miRNAs. This phenomenon results in the substantial decline of the DPV peak current density of the signal labels. The developed TBAPy-MA-COF-COOH-based aptasensor has superior performance for sensing miRNA 155 and miRNA 122 simultaneously, with ultrasensitive low detection limits of 6.7 and 1.5 fM (S/N = 3), respectively, a wide linear range of 0.01-1000 pM, and high selectivity and applicability for serum samples. The proposed TBAPy-MA-based aptasensor demonstrates potential for simultaneous detection of multiple cancer biomarkers by replacing other ssDNA and aptamer strands.

An efficient strategy to achieve hydrophilic polymeric silver(I) materials with exceptional antibacterial activity.

Three isomeric water-soluble and light-stable silver(I) coordination polymers with a fluorinated carboxylate ligand were prepared by template-controlled method, which show different 2D polymeric coordination structures with a novel layered inorganic connectivity in the solid state. In water solution, they dissociate into several stable polynuclear silver(I) oligomers and exhibit extraordinary antimicrobial activities against selected bacteria.

Two novel 3-D coordination polymers with 5-methoxyisophthalate and flexible N-donor co-ligands showing pentanuclear or alternate mono/binuclear Cu(II) units.

Two novel 3-D coordination polymers with different Cu(II) subunits as nodes and mixed bridging ligands as linkers, namely [Cu(5)(µ(3)-OH)(2)(1,3-bip)(2)(CH(3)O-ip)(4)](n) (1) and {[Cu(4)(1,3-btp)(2)(CH(3)O-p)(4)(H(2)O)(2)]·2H(2)O}(n) (2) (CH(3)O-H(2)ip = 5-methoxyisophthalate, 1,3-bip = 1,3-bis(imidazol)propane, 1,3-btp = 1,3-bis(1,2,4-triazol-1-yl)propane), were prepared under hydrothermal conditions. Complex 1 exhibits a CsCl-type network with [Cu(5)(µ(3)-OH)(2)](8+) clusters acting as nodes, which represents the first 3-D network based on pentanuclear Cu(II) clusters. Complex 2 features a 3-D pillared-layer network with (4,6)-connected (4(4).6(2))(4(4).6(8).8(3))-fsc topology, which is a rare example of homometallic coordination polymers constructed by alternate binuclear metal clusters and single metal centres. Variable-temperature magnetic susceptibility measurements show dominant ferromagnetic interactions in the pentanuclear clusters of 1 and strong antiferromagnetic interactions in the dinuclear paddle-wheel units of 2.

Destruction and reconstruction of the robust [Cu2(OOCR)4] unit during crystal structure transformations between two coordination polymers.

This work first demonstrates that the robust [Cu(2)(OOCR)(4)] unit can be destroyed and reconstructed in the solid state, as observed in water-induced structural interconversion of two distinct coordination polymers with 5-bromonicotinate.

Copper(II) 5-methoxyisophthalate coordination polymers incorporating dipyridyl co-ligands: syntheses, crystal structures, and magnetic properties.

Hydrothermal reactions of mixed ligands 5-methoxyisophthalate (CH(3)O-H(2)ip) and dipyridyl with Cu(OAc)(2).2H(2)O afford five new coordination polymers, including {[Cu(CH(3)O-ip)(bpa)].H(2)O}(n) (1), [Cu(2)(CH(3)O-ip)(2)(bpa)(0.5)(H(2)O)](n) (2), [Cu(2)(CH(3)O-ip)(2)(bpp)(H(2)O)](n) (3), {[Cu(3)(CH(3)O-ip)(3)(bpp)(2)(H(2)O)].3H(2)O}(n) (4) and [Cu(4)(CH(3)O-ip)(3)(bpe)(OH)(2)](n) (5) (bpp = 1,3-di(4-pyridyl)propane, bpa = 1,2-bi(4-pyridyl)ethane, and bpe = 1,2-di(4-pyridyl)ethylene). Compound 1 consists of CH(3)O-ip anion-bridged 1D Cu(II) chains that are linked by trans-bpa into a 2D layer. Compound 2 is a 2D (4,4) layer that is connected by CH(3)O-ip anions. The gauche bpa in 2 lies in the cavity and meets the coordination requirement of the paddle-wheel dimeric copper unit. Compound 3 is an extended 3D polythreading network consisting of 2D (4,4) motifs with dangling bpp lateral arms. Compound 4 exhibits a 3D (4,6)-connected self-penetrating (6(5).8)(6(14).8) network that is composed of binuclear and mononuclear metal nodes. Compound 5 exhibits a 3D network with the tetranuclear [Cu(4)(mu(3)-OH)(2)](6+) cluster acting as nodes, which is constructed by the interconnection of 2D helical layers via bpe pillars. The results of magnetic determination show that the syn-anti carboxylato bridges in our cases induce a weak antiferromagnetic interaction in 1, and the syn-syn carboxylato bridge in 3 and 4 mediates a strong antiferromagnetic interaction.