Synthesis of end‐functionalized poly(N‐isopropyl acrylamide) with zinc porphyrin and its photocatalytic activity under visible light

A series of well‐defined linear poly(N‐isopropyl acrylamide) with an asymmetrical zinc(II) porphyrin (ZnPor–PAM) end group was synthesized by atom transfer radical polymerization, wherein 5,10,15,20‐tetra(p‐bromopropanoyloxyethylphenyl) zinc porphyrin tripropionate was used as the initiator and CuBr/tris(2‐dimeoethyl)amine was used as the catalyst system. The structure of the ZnPor–PAM was characterized by Fourier transform infrared spectroscopy and ¹H‐NMR. In addition, the polydispersity index (PDI) obtained by gel permeation chromatography indicated that the molecular weight distribution was narrow; thus, the polymerization was well controlled (1.05 < PDI < 1.21). Because of the incorporation of hydrophobic porphyrin, the lower critical solution temperature of ZnPor–PAM was lower than that of the N‐isopropyl acrylamide homopolymer. Most interestingly, the ZnPor–PAM possessed remarkable photocatalytic activity for the oxidative degradation of methylene blue in the presence of hydrogen peroxide under visible‐light radiation. Moreover, ZnPor–PAM could be reused through the uncomplicated procedure, which exploited the thermoresponsive properties of ZnPor–PAM without any significant loss in activity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40523.     

Influence of a joining helix on the BLUF domain of the YcgF photoreceptor from Escherichia coli

BLUF-domain-comprising photoreceptors sense blue light by utilizing FAD as a chromophore. The ycgF gene product of Escherichia coli is composed of a N-terminal BLUF domain and a C-terminal EAL domain, with the latter postulated to catalyze c-di-GMP hydrolysis. The linkage between these two domains involves a predominantly helical segment. Its role on the function of the YcgF photoreceptor domain was examined by characterizing BLUF domains with and without this segment and reconstituting them with either FAD, FMN or riboflavin. The stability of the light-adapted state of the YcgF BLUF domain depends on the presence of this joining, helical segment and the adenosine diphosphate moiety of FAD. In contrast to other BLUF domains, two-dimensional (1)H,(15)N and one-dimensional (1)H NMR spectra of isotope-labeled YcgF-(1-137) revealed large conformational changes during reversion from the light- to the dark-adapted state. Based on these results the function of the joining helix in YcgF during signal transfer and the role of the BLUF domain in regulating c-di-GMP levels is discussed.     

Morphology Control in Solution‐Processed Bulk‐Heterojunction Solar Cell Mixtures

The efficiency of bulk‐heterojunction solar cells is very sensitive to the nanoscale structure of the active layer. In the past, the final morphology in solution‐processed devices has been controlled by varying the casting solvent and by curing the layer using heat tempering or solvent soaking. A recipe for making the “best‐performing” morphology can be achieved using these steps. This article presents a review of several new techniques that have been developed to control the morphology in polymer/fullerene heterojunction mixtures. The techniques fall into two broad categories. First, the morphology can be controlled by preparing nanoparticle suspensions of one component. The size and shape of the nanoparticles in solution determine the size and shape of the domain in a mixed layer. Second, the morphology can be controlled by adding a secondary solvent or an additive that more strongly affects one component of the mixture during drying. In both cases, the as‐cast efficiency of the solar cell is improved with respect to the single‐solvent case, which strongly argues that morphology control is an issue that will receive increasing attention in future research.     

New arylidene–siloxane polyethers: Liquid‐crystalline and photosensitive properties

By polycondensation reactions, starting from α, ω‐bis(chloromethyl)polydimethylsiloxanes with different molecular weights and 2,6‐bis(4‐hydroxybenzylidene)cyclohexanone, new polyethers were obtained. The structure of resulting polymers was confirmed by IR and ¹H‐NMR spectroscopy and their thermal properties and mesophase behavior were studied by TGA, DSC, and polarizing light microscopy. Depending on the length of the siloxane spacer, some of the obtained compounds exhibited thermotropic liquid‐crystalline properties. A possible smectic texture was investigated by X‐ray diffraction measurements at room temperature. A decrease of the transition temperatures values was observed as the spacer length increased. The photochemical behavior of the siloxane polyethers was studied by ultraviolet absorption spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3093–3099, 2003     

Photon-Ion Catalysis Synergy Material and Its Application

The co-operation action mechanism and model of photon-ion catalysis synergy material composed of thallium and valency-variable rare earth elements and semiconductor oxide were proposed. The radiation catalysis reactions of water and oxygen assisted by the synergy material that could largely increase electron, free radical and negative ion products were discussed. The applications of photon-ion catalysis synergy material in areas of air cleaning material, antibacterial material, healthy material and energy resource material were suggested.     

Preparation of Janus-type superparamagnetic iron oxide nanoparticles modified with functionalized PCL/PHEMA via photopolymerization for dual drug delivery

In this study, superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by the coprecipitation of FeCl₂˙4H₂O and FeCl₃˙6H₂O and applied as a core for preparation of Janus nanoparticles. Accordingly, freshly modified methacrylated iron oxide nanoparticles were reacted with two functionalized polymers. Acrylated poly(ε-caprolactone) (PCL) and acrylated poly(2-hydroxyethyl methacrylate) (PHEMA) were synthesized via ring-opening and free-radical polymerization, respectively, and subsequent modification with acryloyl chloride. Acrylated PCL as the hydrophobic part and acrylated PHEMA as the hydrophilic domain were grafted on the surface of methacrylated iron oxide nanoparticles with two morphologies. Pickering emulsion and solution photopolymerization reactions were used to prepare nanoparticles with “Janus” and “mixed” morphologies, respectively. The products were characterized in each step using Fourier-transform infrared spectroscopy (FT-IR), Proton nuclear magnetic resonance (¹H-NMR), thermogravimetric analysis (TGA), dynamic light scaterring (DLS), transmission electron microscope (TEM), vibrating-sample magnetometer (VSM), energy dispersive X-ray (EDX), and ultraviolet–visible spectroscopy (UV-Vis). Quercetin and 5-FU (as two anticancer drugs) were loaded in the mentioned nanoparticles, and the drug loading capacity and encapsulation efficiency (EE) of these nanoparticles were calculated. in vitro release behavior at two pH values (5.8 and 7.4) and at 37°C demonstrated that morphology can affect the release profile. Finally, rat C6 cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay for drug-free and drug-loaded nanoparticles.     

D-A type hybrid polymers based on EDOT and various benzodiazoles for electrochromic materials

Two donor units (D)-acceptor units (A) type monomers were synthesized by Stille coupling reaction, and then three D-A type hybrid polymers based on 3,4-ethylenedioxythiophene and various benzodiazoles were synthesized by electrochemical polymerization. Spectroelectrochemical and kinetic studies of these polymers showed that all polymer films exhibited excellent electrochromic behavior, obvious optical contrast, and excellent stability. Among them, the response time of P3 film was the shortest (t_c = 1.6 s, t_b = 2.2 s), the coloring efficiency of P2 film was the highest (CE = 333 cm²·C⁻¹), and the stability of P1 was the best (the ΔT loss of P1 after 1000 s cycles is only 2.3%). Therefore, these data prove that these new polymers have great potential in applications as electrochromic materials.     

Processing Chemical and Photonic Signals by Artificial Multicomponent Molecular Systems

Miniaturization has been an essential ingredient in the outstanding progress of information technology over the past fifty years. The next, perhaps ultimate, limit of miniaturization is that of molecules, which are the smallest entities with definite size, shape, and properties. Molecular-level systems that respond to external stimulation by changing some physical or chemical properties can be viewed as input–output devices and therefore may be useful for transferring, processing, and storing information. Some of these nanoscale devices can, in fact, perform logic operations of remarkable complexity. This research — although far from being transferred into technology — is attracting interest, since the nanometer realm seems to be out of reach for the “top-down” techniques currently available to microelectronics industry. Leaving aside futuristic speculations related to the construction of a chemical computer, molecular logic devices could be interesting for specific applications in areas such as diagnostics, medicine, and materials science, where problems need to be addressed in places — for example, inside a cell — that are out of reach for a silicon-based computer. Here we discuss the idea of processing information with artificial multicomponent molecular systems in solution by illustrating a few recent examples developed in our laboratory.