Highly selective halogenation of unactivated C(sp3)–H with NaX under co-catalysis of visible light and Ag@AgX

The direct selective halogenation of unactivated C(sp3)–H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450–500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons

ZnO nanorod arrays assembled on activated carbon fibers for photocatalytic degradation:Characteristics and synergistic effects

Well-aligned ZnO nanorod arrays were assembled on activated carbon fibers by a stepwise sequence of sol-gel and hydrothermal synthesis methods. These ZnO nanorod arrays on activated carbon fibers having different characteristics such as surface area, rod concentration, aspect ratio and defect level, were applied as catalysts for the photodegradation of an aqueous methylene blue solution. They showed very promising methylene blue adsorbility in the dark (ca. 0.025–0.031 mg methylene blue m−2 catalyst, vs. 0.072 mg methylene blue m−2 activated carbon fibers). Significantly, the defect level of ZnO nanorod arrays has a major effect on the turnover frequency compared to other characteristics. A synergistic effect between activated carbon fibers and ZnO nanocrystals on enhancing turnover frequency was more significant for the well-assembled ZnO nanorod arrays on activated carbon fibers catalysts compared to the mechanically mixed ZnO powder with activated carbon fibers catalyst. Further, turnover frequency for the ZnO nanorod arrays on activated carbon fibers (0.00312 molmethylene blue molZnO−1 h−1) was twice higher than that for the corresponding bare ZnO nanorod arrays, and 3 times higher than that for a commercial ZnO powder. In addition, ZnO nanorod arrays on activated carbon fibers show high degradation (77.5%) and mineralization (55.0%) levels for methylene blue, and also good reusability (or stability) as demonstrated by a sequential 5-time recycle routine. These outstanding features indicate that activated carbon fibers supported ZnO nanorod arrays have significant potential to be used as catalysts for photodegradation

Preparation and Characterization of Ni(OH) 2

Mesoporous nanosheets of single-crystalline β-nickel hydroxide (β-Ni(OH)2) were successfully synthesized via a facile hydrothermal method using Ni(NO3)2 · 6H2O as precursor in a mixed solution of sodium hydroxide (NaOH) and sodium dodecylbenzenesulfonate (SDBS). Single-crystalline nickel oxide (NiO) mesoporous nanosheets can be obtained through a thermal decomposition method using β-Ni(OH)2 mesoporous nanosheets as precursor. The influences of SDBS and hydrothermal treatment were carefully investigated; the results showed that they played important roles in the formation of β-Ni(OH)2 mesoporous nanosheets. The as-obtained β-Ni(OH)2 and NiO were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravity-differential thermal analysis (TG-DTA), and specific surface area, and pore size test

A Temperature/pH Double-Responsive and Physical Double-Crosslinked Hydrogel Based on PLA and Histidine

Hydrogel is a good drug carrier, widely used in the sustained-release aspect of tumor drugs, which can achieve the continuous release of drugs to the tumor sites. In this study, diethylene glycol monomethyl ether methacrylate (MEO2MA) and poly (ethylene glycol) methyl ether methacrylate (OEGMA) are temperature-sensitive monomers. N-Methacryloyl-L-Histidine (Mist) is pH sensitive monomer and ligand for metal coordination bond. The temperature-sensitive monomers and pH sensitive monomer with stereocomplex of modified polylactic acid (HEMA-PLLA30/PDLA30) were mixed, under 2,2’-azobis (2-methylpropionitrile) (AIBN) as radical initiator, polymer was formed by free-radical polymerization. The polymer was then immersed in ZnSO4 solution, the imidazole group of Mist monomer forms a tridentate metal coordination bond with Zn2+, temperature/pH double-responsive and physical double-crosslinked hydrogel was finally obtained. Comparing the hydrogen bond hydrogel, hydrogen bond and metal coordination bond double crosslinking hydrogel, metal coordination bond hydrogel, testing thermal stability, viscoelasticity, swelling, and morphology of three hydrogels. In addition, using UV-Visible spectroscopy (UV-Vis) to test the sustained release of the hydrophobic drug doxorubicin hydrochloride (DOX-HCl) in the human tumor environment (37 °C, pH = 5). We found that the temperature/pH double-responsive and physical double-crosslinked hydrogel had the most potential for the sustained drug release

Synthesis and Properties of Hydrogels on Medical Titanium Alloy Surface by Modified Dopamine Adhesion

Medical titanium alloy Ti-6Al-4V (TC4) is an ideal surgical implant material for human tissue repair and replacement. TC4 implantation will be in close contact with human soft tissue and has mechanical compatibility problems. In order to solve this problem, the hydrogel was formed on the surface of TC4 by utilizing the adhesion of dopamine, and the storage modulus of the formed hydrogel matched that of human soft tissue. In this paper, the surface of TC4 was first modified with dopamine (DA) and 2-bromoisobutyryl bromide (BIBB). 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA), oligo (ethylene oxide) methacrylate (OEGMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are used as monomers, and methylenebisacrylamide (MBA) is used as cross-linking agent. Thermosensitive hydrogels were formed on the surface of modified TC4 by the ATRP technique. The successful synthesis of initiator and hydrogels on TC4 was demonstrated by Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The morphology of the hydrogel was observed by the scanning electron microscope (SEM), and the water absorption and temperature sensitivity were investigated by the swelling property. The thermal and mechanical properties of these gels were measured using thermal analysis system (TAS) and dynamic mechanical analyzer (DMA). The results show that the hydrogel on TC4 has good thermal stability and storage modulus that matches human soft tissue

Preparation and swelling behavior of a novel self-assembled β-cyclodextrin/acrylic acid/sodium alginate hydrogel

A novel biodegradable β-cyclodextrin/acrylic acid/sodium alginate (CSA) hydrogel with a three-dimensional network structure was self-assembled by inverse suspension copolymerization. The CSA resin was pH sensitive and had good water absorption properties in pH 6-8 buffer solutions. At a β-CD:AA:SA mass ratio of 1:9:3 the CSA water absorbency was found to be 1403 g/g and the CSA hydrogel strength was 4.968 N. In 0.005-0.1 mol/L chloride salt and sulfate salt solutions the CSA water absorbencies increased as follows: NaCl\u3eKCl\u3eMgCl2\u3eCaCl2\u3eFeCl3, and Na2SO4\u3eK2SO4\u3eFeSO4\u3eAl2(SO4)3, respectively. The release of water from the CSA hydrogel occurred slowly over 120 h. The biodegradation efficiency of the resin reached 85.3% for Lentinula edodes. The super water absorbency, good salt resistance and excellent water retention properties of CSA make it suitable for application as an agricultural water retention agent in saline soils

Novel Amphiphilic, Biodegradable, Biocompatible, Thermo-Responsive ABA Triblock Copolymers Based on PCL and PEG Analogues via a Combination of ROP and RAFT: Synthesis, Characterization, and Sustained Drug Release from Self-Assembled Micelles

Well-defined novel, linear, biodegradable, amphiphilic thermo-responsive ABA-type triblock copolymers, poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate]-b-poly(ε-caprolactone)-b-poly[2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate] [P(MEO2MA-co-OEGMA)-b-PCL-b-P(MEO2MA-co-OEGMA)] (tBPs), were synthesized via a combination of ring-opening polymerization (ROP) of ε-caprolactone (εCL) and reversible addition-fragmentation chain transfer polymerization (RAFT) of MEO2MA and OEGMA comonomers. The chemical structures and compositions of these copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (1H NMR). The molecular weights of the copolymers were obtained using gel permeation chromatography (GPC) measurements. Thermo-responsive micelles were obtained by self-assembly of copolymers in aqueous medium. The temperature sensitivity and micelllization behavior of amphiphilic triblock copolymers solutions were studied by transmittance, fluorescence probe, surface tension, dynamic light scattering (DLS) and transmission electron microscopy (TEM). A hydrophobic drug, anethole, was encapsulated in micelles by using the dialysis method. The average particle sizes of drug-loaded micelles were determined by dynamic light scattering measurement. In vitro, the sustained release of the anethole was performed in pH 7.4 phosphate-buffered saline (PBS) at different temperatures. Results showed that the triblock copolymer’s micelles were quite effective in the encapsulation and controlled release of anethole. The vial inversion test demonstrated that the triblock copolymers could trigger the sol-gel transition which also depended on the temperature, and its sol-gel transition temperature gradually decreased with increasing concentration. The hydrogel system could also be used as a carrier of hydrophobic drugs in medicine

Sustainable Afterglow Room-Temperature Phosphorescence Emission Materials Generated Using Natural Phenolics

Long-lived afterglow room-temperature phosphorescence (RTP) from natural phenolics has seldom been reported yet this is essential for the development of sustainable afterglow RTP materials. With this research, we have prepared sustainable afterglow RTP materials (GA@SA) with a lifetime of up to ≈934.7 ms by embedding gallic acid (GA) within a Ca2+-crosslinked sodium alginate (SA) matrix. Theoretical simulations indicate that the restricted carbonyl moieties of the GA and H-type aggregates of GA in a SA matrix promoted the spin orbit coupling (SOC) of GA and induced afterglow emission. Moreover, afterglow RTP emission could be produced by embedding different types of natural phenolics such as, tannic acid, caffeic acid and chlorogenic acid into Ca2+-crosslinked networks of SA. As an illustration of potential applications, GA@SA was used to prepare anti-counterfeit afterglow clothing and paper. This work provides an innovative method for the activation of long-lived afterglow RTP from sustainable phenolics.</p