Synthesis and characterization of amphiphilic and hydrophobic ABA-type tri-block copolymers using telechelic polyurethane as atom transfer radical polymerization macroinitiator

Indulgent of the physiochemical features of MgCr-LDH nanosheets towards photodegradation process of methylene blue

In the present work, we report the preparatory strategy of MgCr-layered double hydroxide (LDH) nanosheets with 90% degree of delamination by employing a formamide-assisted co-precipitation and mild hydrothermal route for the degradation of methylene blue (MB) under solar light exposure. The as-synthesized MgCr-LDH nanosheets were characterized by assorted characterization techniques such as powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), Raman, thermogravimetric analysis (TGA), N₂ adsorption-desorption measurement, X-ray photoelectron spectroscopy (XPS) and UV-Visible diffused reflectance spectroscopy (UV-DRS). The XRD pattern of MgCr-LDH nanosheets quantified the strain (ε) and dislocation density (δ) of 1.371 lines^-2 m^-4 and 0.5723 lines m^-2 related to the (110) plane with d-spacing value of 1.6169 Ȧ. With a minimum band gap of ∼2.63 eV, the as-synthesized MgCr-LDH nanosheets displayed 90.6% MB photodegradation under the experimental protocols such as catalyst dosage of 30 mg/L, initial MB concentrations of 20 ppm, pH of 7 and time duration of 2 h under solar light exposure. Further, the recyclability test of the photocatalyst signifies material stability up to four successive cycles with 90% retention of MB degradation under sunlight exposure. The superior catalytic performances of the MgCr-LDH nanosheets could be ascertained to the suppression of excitonic recombination and effective light harvestation properties, synergistically contributed by the porous structural aspects via association of uni/multi-lamellar nanosheets, surface defect sites and photoactive Cr³⁺ cations. Additionally, the surface -OH groups of LDH contributed towards the generation of ^•OH radicals for triggering the catalytic performances. This type of work advances the novel ideas for establishing highly potent photocatalysts via synergizing structural and surface properties, paving towards effective wastewater treatment.

Linear Block Copolymer Synthesis

Block copolymers form the basis of the most ubiquitous materials such as thermoplastic elastomers, bridge interphases in polymer blends, and are fundamental for the development of high-performance materials. The driving force to further advance these materials is the accessibility of block copolymers, which have a wide variety in composition, functional group content, and precision of their structure. To advance and broaden the application of block copolymers will depend on the nature of combined segmented blocks, guided through the combination of polymerization techniques to reach a high versatility in block copolymer architecture and function. This review provides the most comprehensive overview of techniques to prepare linear block copolymers and is intended to serve as a guideline on how polymerization techniques can work together to result in desired block combinations. As the review will give an account of the relevant procedures and access areas, the sections will include orthogonal approaches or sequentially combined polymerization techniques, which increases the synthetic options for these materials.

Tailor-made zwitterionic polyurethane coatings: microstructure, mechanical property and their antimicrobial performance

Introduction of zwitterions into polyurethane markedly increases micro-phase separation and tensile property, and endow the surfaces with anti-mold adhesion performance.

Synthesis of well-defined α-fluorinated alkyl ester, ω-carboxyltelechelic polystyrenes and fabrication of their hydrophobic highly ordered porous films and microspheres

Porous films and microspheres of α-fluorinated alkyl ester, ω-carboxyl telechelic polystyrenes synthesized via combining aminolysis of RAFT-polystyrene with thiol–ene “click” reaction.

Preparation of polyurethane with zwitterionic side chains and their protein resistance

Polyurethane (PU) with zwitterionic side chains has been prepared to resist nonspecific adsorption of proteins. First, dihydroxy-terminated poly(2-(dimethylamino)ethyl methacrylate) (PDEM(OH)(2)) is synthesized by free radical polymerization with 3-mercapto-1,2-propanediol as the chain transfer agent, which polyadds with diisocyanate to yield a PU with PDEM side chains. Such side chains are zwitterionized by 1,3-propane sultone. Proton nuclear magnetic resonance spectroscopy ((1)H NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) show that the zwitterionic side chains are incorporated into the PU. Thermal analysis demonstrates the thermal stability is greatly affected by the content of the side chains. By use of quartz crystal microbalance with dissipation (QCM-D), we have investigated the adsorption of fibrinogen, bovine serum albumin, and lysozyme on a surface constructed by such a PU. It shows the PU has a controllable protein resistance depending on the content of the zwitterionic side chains.