A Photocured Bio-based Shape Memory Thermoplastics for Reversible Wet Adhesion.

Development of reversible wet or underwater adhesives remains a grand challenge. Because weakened intermolecular interactions by water molecules or/and low effective contact area cause poor interface to the wet surfaces, which significantly decreases adhesive strength. Herein, a new photocured, bio-based shape memory polymer (SMP) that shows both chemical and structural wet adhesion to various types of surfaces is developed. The SMP is polymerized from three monomers mainly from bio-sources to form linear polymer chains dangled with hydrophobic side chains. The hydrogen acceptor and donor groups in the chains form hydrogen bonding with the surfaces, which is protected by the hydrophobic chains in the interface. The SMP shows tunable phase transition temperature (Tg) of 17-38 °C. In a rubbery state above Tg, the adhesive forms conformable contact with the targeted surfaces. Below Tg, a transition to a glassy state locks the conformed shapes to largely increase the effective contact area. As a result, the adhesive exhibits long-term underwater adhesion of > 15 days with the best adhesion strength of ~ 0.9 MPa. Its applications in leak repair, underwater on-skin sensors were demonstrated. This new, general strategy would pave avenues to designing bio-based, long-lasting, and reversible adhesives from renewable feedstocks for widespread applications.

Coordination-driven assembly of a 3d-4f heterometallic organic framework with 1D Cu4I4 and Eu-based chains: syntheses, structures and various properties.

A three-dimensional porous 3d-4f heterometallic organic framework, namely, {[Eu3(Cu4I4)3(INA)9(DMF)4]·3DMF}n (YNU-2), was successfully prepared under solvothermal conditions. There are two different one-dimensional metal chains in the structure, namely, Cu4I4 and EuIII-based chains, resulting in an excellent stability of the prepared sample. A N2 sorption isotherm at 77 K revealed that the activated sample exhibits a Brunauer-Emmett-Teller surface area of 371 m2 g-1, while, YNU-2 can adsorb obviously higher CO2 amounts than CH4 at 273 K and 298 K under 1 atm because of the stronger interaction force between CO2 and the porous skeleton. Furthermore, YNU-2 is highly efficient heterogeneous catalyst for chemical fixation of the CO2 and epoxides into cyclic carbonates with a preferable recyclability. Taking into account its excellent stability, the prepared sample can be used to construct an electrochemical adapter sensor for detecting cocaine with a detection limit of 0.27 pg mL-1 in the wide range of 0.001-0.5 ng mL-1.

Assembly of Two Self-Interpenetrating Metal-Organic Frameworks Based on a Trigonal Ligand: Syntheses, Crystal Structures, and Properties.

Two self-interpenetrating metal-organic frameworks (MOFs) 1 and 2 were designed and constructed through the coordination self-assembly of transition metal nodes and a trigonal ligand. They both exhibit interesting three-dimensional constructions with the 1 + 2 self-locked mode. Because of the outstanding moisture susceptibility and luminescence property, MOF 1 has a potential detectability toward nitrofurantoin (NFT) in water. More importantly, MOF 1 can efficiently monitor NFT in bovine serum. Taking into account of Lewis basic sites in the skeleton, MOF 2 can be implemented as an outstanding heterogeneous catalyst for the Knoevenagel reaction. Furthermore, they both reveal excellent circularity and an application effect for five cycles.

Rational design and synthesis of a stable pillar-layer NaI-organic framework as a multi-responsive luminescent sensor in aqueous solutions.

A stable pillar-layer NaI-organic framework, [Na2(DCPB)∙(H2O)2]n (namely 1), was rationally designed and synthesized by the assemble process of NaI and 1,3-di(4'-carboxyl-phenyl)benzene (H2DCPB). Benefiting from the luminescent property and high stability in water, the as-synthesized 1 is a potential multi-responsive luminescent sensor material toward Cr2O72-, Fe3+, and nitrofurazone (NFZ) in water. Ground 1 not only has the excellent detectability and selectivity but also possesses outstanding stability and circularity. The calculated Ksv values of 1 are 8.8×103 for Fe3+, 9.9×103 for Cr2O72-, and 2.7×104 M-1 for NFZ in aqueous solutions, respectively. Furthermore, 1 is able to accurately detect NFZ in real bovine serum samples through luminescence detection technology.

An excellently stable TbIII-organic framework with outstanding stability as a rapid, reversible, and multi-responsive luminescent sensor in water.

An excellently stable TbIII-organic framework, [TbL·2H2O]n (complex 1), has been successfully synthesized through an assembly process. By virtue of its excellent water stability and strong green luminescence, complex 1 has been considered and applied as a reversible multi-responsive luminescent sensor for Fe3+, Cr2O72-, and nitrofurantoin (NFT) aqueous solutions. Complex 1 not only exhibits outstanding detection effects with high selectivity and sensitivity, but also shows remarkable cycling and regeneration abilities. The Ksv values of complex 1 for Fe3+, Cr2O72-, and NFT are 2.27 × 104, 2.31 × 104, and 5.26 × 104 M-1 in water systems, respectively. More importantly, complex 1 can accurately monitor NFT in real bovine serum samples via luminescence quenching detection.

Construction of direct Z-scheme system for enhanced visible light photocatalytic activity based on Zn0.1Cd0.9S/FeWO4 heterojunction.

A novel direct Z-scheme Zn0.1Cd0.9S/FeWO4 (ZCS/FW) photocatalyst was prepared by a facile calcination method. The photocatalytic performance was investigated by photodegradation rhodamine B (RhB) and photocatalytic production hydrogen (H2) under visible light irradiation. Compared with the pure ZCS, the ZCS/FW composites show considerably improved photocatalytic activity for degradation RhB and production H2. Noticeably, the ZCS/FW with 7 wt% of FW exhibits optimal photocatalytic activity with the H2 evolution rate of 34.6 mmol g-1 h-1 and photodegradation of about 98% of RhB solution (10 mg l-1) in 60 min. These outstanding photocatalytic performances were found to be ascribed to the formation of direct Z-scheme heterojunction, resulting in effective separation and transfer of photogenerated charge carriers. Moreover, active species trapping experiments further demonstrate the electrons transfer followed Z-scheme system, and the photocatalytic mechanism was proposed.

Controlled fabrication and characterization of microspherical FeCO3 and α-Fe2O3.

In this paper, the microspherical Fe(2)O(3) was successfully obtained by calcining the FeCO(3) sphere prepared by a hydrothermal route. The sphere morphology perfectly remained after the calcination of FeCO(3) but the diameter of sphere decreased in a certain degree from 70-100 µm to 50-70 µm, which might be due to some loss of quantity during the calcination (FeCO(3)-Fe(2)O(3)). The sphere was solid and highly densified. At the same time, the effects of factors influencing the formation of FeCO(3), such as PVP, reaction temperature were investigated. The simple formation process of FeCO(3) was also proposed as follows: Fe(2+) produced by the reduction of Fe(3+) reacted with CO(3)(2-) released from the decomposition of urea to form FeCO(3) nanoparticle. Then, the formed nanoparticles aggregated together to produce sphere structure via oriented attachment. With the reaction time increasing, the sphere became solidness and densification.