π‐Plasmon absorbance films of carboxylic functionalized CNTs coupled with renewable PGP platforms

π‐Plasmon absorbance films of carboxylic functionalized multiwall carbon nanotubes (CNTs) coupled with renewable and recycled polycaprolactone grafted pectin (PGP) platforms as successful alternative for ordinary nondegradable platforms were investigated. Characterization of the synthesized carboxylic functionalized CNTs was performed using ¹H NMR and attenuated total reflectance Fourier transform infrared for structural identification, thermogravimetric analysis and derivative thermogravimetric analysis for thermal stability, and X‐ray powder diffraction for crystal structure, whereas the characterization of prepared PGP was done by means of attenuated total reflectance Fourier transform infrared for chemical structure, differential scanning calorimetry for melting endotherms of polycaprolactone and high crystalline structure of PGP, and thermogravimetric analysis and derivative thermogravimetric analysis for thermal stability of PGP. Fabrication of water‐dispersed carboxylic functionalized CNTs coupled with PGP films was performed by casting technique in the presence of Ca²⁺ as cross‐linker. The thin films were tested for π‐plasmon absorbance using UV‐Vis spectrometry. Different fractions of carboxylic functionalized CNTs and PGP films demonstrated π‐plasmon absorbance broad peaks at λ_max = 232 nm, which corresponded to 5.36 eV. The fabrication of novel films from renewable recycled PGP platform and advanced carboxylic functionalized CNTs properties will be the key features for many of next forthcoming technologies. The PGP considered as environment‐friendly and easily degradable platforms will be a successful alternative for conventional nondegradable electronic platforms, and water‐dispersed carboxylic functionalized CNTs with advanced properties will be finding accelerating executive applications.     

A route toward multifunctional polyurethanes using triple click reactions

The aliphatic polyurethane with pendant alkyne, perfluorophenyl, and anthracene moieties (PU‐anthracene) was prepared from polycondensation of anthracene, alkyne, and perfluorophenyl functional‐diols with hexamethylenediisocyanate in the presence of dibutyltindilaurate (DBTL) in CH₂Cl₂ at room temperature for 10 days. Thereafter, the PU‐(anthracene‐co‐alkyne‐co‐perfluorophenyl) (M_n,GPC = 15,400 g/mol, M_w/M_n= 1.37, relative to PS standards) was sequentially clicked with benzyl azide, octylamine, and 4‐(2‐hydroxyethyl)?10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐ene‐3,5‐dione (adduct alcohol) via copper‐catalyzed azide‐alkyne cycloaddition, active ester substitution and Diels–Alder reactions, respectively, to finally yield PU‐(hydroxyl‐co‐benzyltriazole‐co‐octylamine). The PUs were characterized using ¹H NMR, GPC, and DSC. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 480–486     

Theoretical investigation of the decomposition of acyl azides: Molecular orbital treatment

The thermal decomposition of formyl, acetyl, and benzoyl azides to the corresponding isocyanate and nitrogen has been treated theoretically using ab initio molecular orbital calculations at the Møller–Plesset type 2 (MP2)(full)/6‐31G* level. The reaction is stimulated by elongation of N N bond and is followed until the formation of the isocyanate and expulsion of nitrogen. The decomposition of formyl azide proved to be a concerted one‐step reaction without the formation of a nitrene intermediate. In contrast, the conversion of both acetyl and benzoyl azides to the corresponding isocyanate and nitrogen is a two‐step reaction, and a nitrene intermediate is formed. One transition state is located and identified during the course of the conversion of formyl azide, but two transition states are located and identified during the course of the conversion of acetyl and benzoyl azides. The thermodynamic functions, ΔE_r and ΔH_r, of the studied reactions are calculated. The results predict that the ease of conversion of the acyl azide to the isocyanate and nitrogen goes in the order: formyl azide > acetyl azide > benzoyl azide. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

紫外光接枝季铵盐抗菌聚乙烯膜的制备和表征

近年来出现的高分子杀菌剂,又称表面接触消毒剂,是将杀菌基团结合在不溶性载体上．此类杀菌剂不仅可以有效的避免二次污染,而且可以重复利用．由于杀菌基团集中在载体表面且浓度高,也使得消毒时间缩短．这些优点使高分子杀菌剂成为目前研究的热点。     

Photochemical grafting of polysulfobetaine onto polyethylene and polystyrene surfaces and investigation of long‐term stability of the polysulfobetaine layer in seawater

Low‐density polyethylene (LDPE) and polystyrene (PS) films with hydrophilic surface were prepared by photochemical grafting of sulfobetaine‐based copolymer containing photolabile moiety, and long‐term stability of the hydrophilic nature of the surfaces in seawater was proved. The sulfobetaine‐based copolymer was prepared by copolymerization of N,N‐dimethyl‐N‐(3‐(methacryloylamino)propyl)‐N‐(3‐sulfopropyl) ammonium betaine with 2 or 5 mol% of N‐methacryloyl‐4‐azidoaniline, and the resulted polymers were grafted onto the plasma pretreated LDPE and PS films. The contact angle measurements were used to prove the modification as well as to follow the changes in the hydrophilicity during storage at room temperature under air atmosphere as well as in seawater at 32°C. The stability of the polymer layer was confirmed also by FTIR and AFM. Polysulfobetaine‐modified LDPE and PS surfaces exhibited significantly higher long‐term hydrophilicity compared with only plasma treated LDPE and PS surfaces.     

Linearly ‐π‐ extended porphyrins: Synthesis of novel tetrabenzoylporphyrins

The π‐extended porphyrins 11a – c with a λ_max = 644, 643 and 639 nm were synthesized by an acid catalysed reaction of the dipyrrolylmethane 10 with different aldehydes followed by oxidation with 2,3‐dichloro‐5,6‐dicyano‐1,4‐quinone (DDQ). In a second approach, 10 was decarboxylated to yield 12, which was treated with DMF and benzoylchloride to give the diformyl compound 13. Acid catalysed reaction of 12 and 13 led to the porphyrin 11a after oxidation.     

Photochromic fulgides: Transformation of the non‐photochromic (Z)‐isomer of a fulgide into a highly photochromic (E)‐isomer via structural modification involving enhanced conjugation

The non‐photochromic fulgide (1‐Z) has been successfully converted into the highly photochromic ( 3‐Z ) analogue. A dicyanomethylene group was introduced at the 5‐position of 1‐Z in order to enhance the latter's conjugation properties that would facilitate the photochemical Z→E isomerization process. The irradiation of the product 3‐Z with a UV light at λ_max 350 nm formed a bluish green solution which absorbed at λ_max 620 nm, corresponding to the ring‐closed product 4. The latter was also formed from the reference dicyanomethylene product 3‐E synthesized from 1‐E. The irradiation of 4 at λ_max 532 nm produced the reversion to the original pale yellow color of 3‐E.     

Toughening of a copolyester with a maleated core‐shell toughener

A reactive extrusion process was developed to toughen an amorphous copolyester (PETG) of ethylene glycol, terephthalic acid and 1,4‐cyclohexanedimethanol using either a maleic anhydride grafted polyethylene–octene elastomer (POEg), or a maleic anhydride grafted mixture (TPEg) of the polyethylene–octene elastomer and a semicrystalline polyolefin plastic as the impact modifier. TPEg showed an important toughening effect on the PETG. A sharp ductile‐brittle transition was observed when the TPEg content was about 10 wt %. For POEg toughened PETG, the ductile–brittle transition required a higher content in POEg, ∼15 wt %. Evolution of the topography and morphology of the blends and the relationship between impact strength and topography were discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2801–2809, 2000     

Photochemical modification of polyethylene surface with aryl azides

It has been shown that the formation of a covalently grafted modifying layer takes place during the photolysis of polycrystalline layers of 2-azidoanthraquinone and 4-azidobenzoyl azide on the surface of polyethylene. Its thickness is determined by the amount of the azide applied, and phenyl isocyanate groups formed by the photolysis of 4-azidobenzoyl azide are prone to further functionalization of the modified surface with primary amines.     

Synthesis and properties of cationic polyelectrolyte with regioregular polyalkylthiophene backbone and ionic‐liquid like side groups

High‐regioregular poly{3‐[6‐(1‐methylimidazolium‐3‐yl)hexyl]thiophene‐2,5‐diyl bromide}, PMHT‐Br, has been prepared by reaction of high‐regioregular (above 92%) poly[3‐(6‐bromohexyl)thiophene‐2,5‐diyl] with 1‐methylimidazole. PMHT‐Br is soluble in water and water miscible solvents such as methanol, DMSO and shows solvatochromism; λ_max (nm): 423 (H₂O); 435 (MeOH); 452 (DMSO). Increased absorption band broadening observed for aqueous solution as well as NMR spectra in D₂O suggests a micelle‐like structure of PMHT‐Br molecules in these solutions: poly(3‐hexylthiophene) core and 1‐methylimidazolium bromide shell. Despite the disturbing effect of ionic groups, the solid‐state PMHT‐Br shows absorption maximum at 520 nm, the band edge at 660 nm (ca. 1.9 eV), and fluorescence emission with maximum at 635 nm, in a good agreement with the polymer regioregularity. Fluorescence emission maxima: λ_em (nm): 598 (H₂O); 562 (MeOH); 574 (DMSO), occur in a vicinity of corresponding adsorption band edges. Plot of electrical conductivity of PMHT‐Br (measured under the dynamic vacuum conditions, 5 × 10^?5 Pa) versus 1/T shows a break at about 70 °C same as the temperature dependence of λ_max of the solid PMHT‐Br. These breaks indicate an increase in the mobility of polymer segments and ions within PMHT‐Br; however, a thermal analysis did not provide solid evidence for it. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3073–3081, 2010     

Photochemistry of amphiphilic copolymers: Fluorescence spectra of copolymers of 1-(2-naphthyl)ethyl methacrylate and sodium 2-acrylamido-2-methylpropanesulfonate in solution

Amphiphilic copolymers containing 1-(2-naphthyl)ethyl ester groups were prepared and their fluorescence properties were examined. The fluorescnce spectra of the copolymers with a higher naphthyl content showed predominantly a broad monomer emission with λ_max at 340 nm in methanol, whereas a structured emission with λ_max at 344 and 362 nm was observed in aqueous solution. The former spectra changed rapidly to the latter ones upon UV irradiation. Photolysis of the copolymers and the monomeric model compound in methanol gave 2-vinylnaphthalene, whose fluorescence agreed with those of copolymers in water, together with methyl ether, alkylnaphthalenes, and other products. These results indicate that the copolymers hold vinylnaphthalene-like traps, which may emit preferentially in water because of efficient sensitization. © 1995 John Wiley & Sons, Inc.     

Synthesis,photophysical properties and DFT studies of 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl)hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile dye

The chromophore 2-(3-cyano-4-((2-(4,6-dimethyl-5-nitro-1H-pyrazolo[3,4-b]pyridin-3-yl) hydrazono)methyl)-5,5-dimethylfuran-2(5H)-ylidene)malononitrile (PPHTCF) was synthesized through coupling of diazotized 3-amino-4,6-dimethyl-5-nitropyrazolo[3,4-b]pyridine with 3-cyano-2-(dicyanomethylene)-4,5,5-trimethylfuran (TCF). The absorption solvatochromism behaviour of PPHTCF, in various solvents, presented ΔE_max = +5.40 where the positive sign suggested red shift occurrence, implying that the PPHTCF has more polar lowest excited state than its ground one. While, the PPHTCF fluorescence spectra afforded λ_em, in 575–633 nm range, and was more dependent on the solvent polarity than the absorption λ^max, despite both exhibited red shift by 58 and 42 nm, respectively. To discover the PPHTCF solvatochromism behaviour in term of “Stokes’ shift”, both of Lippert-Mataga and linear solvation-energy relationship (LSER) formulations have been utilized and the outcomes endorsed that the later was better than the former (R² = 0.9728). Finally, TD-DFT simulated absorption and emission spectra in EtOH revealed that λ^max has been resulted mainly from HOMO → LUMO; HOMO-5 → LUMO and HOMO-2 → LUMO transitions, respectively.     

Photochemical grafting and activation of organic layers on glassy carbon and pyrolyzed photoresist films

Organic films have been grafted to polished glassy carbon (GC) and as-prepared pyrolyzed photoresist film (PPF) by photolysis of alkenes and an alkyne. The alkene or alkyne is spin-coated onto the carbon surface and photolyzed in air at 254 nm. Characterization by water contact angle measurements, depth profiling and surface roughness measurements using atomic force microscopy (AFM), and electrochemistry reveal that for most modifiers a loosely packed monolayer is grafted to the surface. Grafted layers of 1-decene were further reacted by drop-coating with oxalyl chloride and photolyzing at 254 nm in air. The procedure adds acid chloride groups to the film. Amines were attached to these films via amide bond formation, and were characterized by electrochemistry and assembly of citrate-capped gold nanoparticles. Amines were also coupled to photografted 1-undecylenic acid layers and to carboxyphenyl layers prepared by electroreduction of the corresponding diazonium salt. Quantitative analysis using electrochemistry established that the highest concentration of amines was attached to the oxalyl chloride treated film, and that a higher concentration of amines was attached via reaction with the photografted 1-undecylenic acid layer than the electrografted carboxyphenyl layer. Thus photografting and photoreaction with oxalyl chloride are simple methods for generating amine-reactive tethers on GC and PPF surfaces.     

Autonomic healing of a pinhole in polyethylene and photografted polyethylene‐g‐poly(hexyl methacrylate) films

The structural changes of polyethylene (PE) and photografted polyethylene‐g‐poly(hexyl methacrylate) (PE‐g‐PHMA) with the mechanical formation of pinholes were evaluated with differential scanning calorimetry, wide‐angle X‐ray scanning, and small‐angle X‐ray scanning. The crystallinity and the long period of the lamella increased with pricking under extremely high compression stress. The partial transformation of an orthorhombic crystal into a monoclinic one was also detected. The autonomic healing of pinholes in PE and PE‐g‐PHMA was studied in detail. The degree of healing increased with an increase in the grafting ratio of poly(hexyl methacrylate) (PHMA). Three mechanisms for the healing were investigated and related to the molecular motions of PE and PHMA grafted chains, which were evaluated with dynamic mechanical analyses. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1705–1714, 2004     

On the Reactivity Enhancement of Graphene by Metallic Substrates towards Aryl Nitrene Cycloadditions

Pristine graphene is fairly inert chemically, and as such, most application-driven studies use graphene oxide, or reduced graphene oxide. Using substrates to modulate the reactivity of graphene represents a unique strategy in the covalent functionalization of this otherwise fairly inert material. It was found that the reactivity of pristine graphene towards perfluorophenyl azide (PFPA) can be enhanced by a metal substrate on which graphene is supported. Results on the extent of functionalization, defect density, and reaction kinetics all show that graphene supported on Ni (G/Ni) has the highest reactivity toward PFPA, followed by G/Cu and then G/silicon wafer. DFT calculations suggest that the metal substrate stabilizes the physisorbed nitrene through enhanced electron transfer to the singlet nitrene from the graphene surface assisted by the electron rich metal substrate. The G/Ni substantially stabilizes the singlet nitrene relative to G/Cu and the free-standing graphene. The product structure is also predicted to be substrate dependent. These findings open up opportunities to enhance the reactivity of pristine graphene simply through the selection of the substrate. This also represents a new and powerful approach to increasing the reactivity of singlet nitrenes through direct electronic communication with graphene.     

Visible‐light‐driven Efficient Photocatalytic Reduction of Organic Azides to Amines over CdS Sheet–rGO Nanocomposite

CdS sheet–rGO nanocomposite as a heterogeneous photocatalyst enables visible‐light‐induced photocatalytic reduction of aromatic, heteroaromatic, aliphatic and sulfonyl azides to the corresponding amines using hydrazine hydrate as a reductant. The reaction shows excellent conversion and chemoselectivity towards the formation of the amine without self‐photoactivated azo compounds. In the adopted strategy, CdS not only accelerates the formation of nitrene through photoactivation of azide but also enhances the decomposition of azide to a certain extent, which entirely suppressed formation of the azo compound. The developed CdS sheet‐rGO nanocomposite catalyst is very active, providing excellent results under irradiation with a 40 W simple household CFL lamp.     

The High‐Pressure Phase of MgB2C2

A high‐pressure modification of MgB₂C₂ was synthesized and structurally characterized. The compound crystallizes in the orthorhombic space group Pnnm, with the lattice parameters a = 7.19633(3) Å, b = 4.61791(13) Å and c = 2.77714(8) Å. The compound contains heterographene B–C nets, isoelectronic to graphite, just like the ambient pressure modification. The layers are intercalated by magnesium atoms, which are arranged in a chain‐like manner. According to Density Functional Theory (DFT) calculations, the high‐pressure form of MgB₂C₂ is a semiconductor with a band gap of 1.02 eV. The compound does not undergo a superconducting transition down to 2 K.     

Large-Scale Molecular Dynamics Simulations of Energetic Ni Nanocluster Impact onto the Surface

On the atomic scale, Molecular Dynamics (MD) Simulation of Nano Ni cluster impact on Ni (100) substrate surface have been carried out for energies of E _a = 1–5 eV/atom and total energy of E _T = 195 eV (the total energy of cluster is E _T = nE _a, n is the number of cluster atoms) to understand quantitatively the interaction mechanisms between the cluster atoms and the substrate atoms. The many-body Embedded Atom Method (EAM) was used in this simulation. We investigated the maximum substrate temperature T _max and the time t _max within which this temperature is reached as a function of cluster sizes and the total energy E _T. The temperature T _max is linearly proportional to total cluster energy. For the constant energy per atom and for the cluster size increase, the correlated collisions rapidly transfers energy to the substrate, and the time t _max approached a constant value. For constant total energy the temperature T _max and the time t _max versus different cluster sizes was studied. We showed that the cluster implantation and sputtering atoms from the surface are affected by the cluster size and total kinetic energy of the clusters. Finally time dependence of the number N _dis of disordered atoms in the substrate was observed.     

Monte carlo simulations of polydisperse polymers grafted on spherical surfaces

This article presents effects of polydispersity in polymers grafted on spherical surfaces on grafted polymer chain conformations, grafted layer thickness, and free‐end monomer distribution within the grafted layer. At brush‐like grafting densities, as polydispersity index (PDI) increases, the scaling exponent of radius of gyration of grafted chains approaches that of a single chain grafted on the same nanoparticle, because polydispersity alleviates monomer crowding within the brush. At high PDI, the chains shorter than the number average chain length, N_n, have more compressed conformations, and the chains longer than N_n overall stretch less than in the monodisperse case. As seen in polydisperse flat brushes at high grafting densities, the grafted layer thickness on spherical nanoparticle increases with PDI. Polydispersity eliminates the region near the surface devoid of free‐end monomers seen in monodisperse cases, and it reduces the width of free‐end monomer distribution and shifts the free‐end monomer distribution close to the surface. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Scalable Antifouling Reverse Osmosis Membranes Utilizing Perfluorophenyl Azide Photochemistry

We present a method to produce anti‐fouling reverse osmosis (RO) membranes that maintains the process and scalability of current RO membrane manufacturing. Utilizing perfluorophenyl azide (PFPA) photochemistry, commercial reverse osmosis membranes were dipped into an aqueous solution containing PFPA‐terminated poly(ethyleneglycol) species and then exposed to ultraviolet light under ambient conditions, a process that can easily be adapted to a roll‐to‐roll process. Successful covalent modification of commercial reverse osmosis membranes was confirmed with attenuated total reflectance infrared spectroscopy and contact angle measurements. By employing X‐ray photoelectron spectroscopy, it was determined that PFPAs undergo UV‐generated nitrene addition and bind to the membrane through an aziridine linkage. After modification with the PFPA‐PEG derivatives, the reverse osmosis membranes exhibit high fouling‐resistance.