Synthesis and surface analysis of self-matt coating based on waterborne polyurethane resin and study on the matt mechanism

Self-matt coating of waterborne polyurethane (WBPU) was synthesized by combining prepolymer and self-emulsification methods. The emulsion was fabricated from both hydroxy carboxylic acid and aminosulfonic acid types of hydrophilic chain-extending agents, in which the 2-[(2-aminoethyl) amino] ethane sulphonate sodium (AAS salt) was produced in laboratory. This emulsion demonstrated an excellent matt performance without the addition of extra matting agents after filming. Four different kinds of surface properties were measured on the film: the specular gloss (60° gloss meter), the contact angle (CA), the surface roughness degree (3D Surface Profilometer), and the topography of the coatings surface (SEM). The results showed that tons of spherical particles with diameter in a few micrometers were aggregated on the film surface. The effect of the roughness parameters (R _a and R _q ) and the average particle size of the emulsions on the specular gloss degree were probed. The research indicated that the emulsion with average particle size in the range of 2.5–3.0 µm and, meanwhile, the film with roughness parameters R _a and R _q both greater than 1 µm could attain the best matt effect. The WBPU emulsions showed good physical and mechanical properties, and were introduced into wood varnish for matting purpose.     

Synthesis,characterization and thermal dehydration and degradation kinetics of chitosan Schiff bases of <Emphasis Type="Italic">o</Emphasis>-, <Emphasis Type="Italic">m</Emphasis>- and <Emphasis Type="Italic">p</Emphasis>-nitrobenzaldehyde

The chitosan Schiff bases were synthesised through the condensation reaction of chitosan with o-, m- and p-nitrobenzaldehyde (abbreviated as CSB-o, CSB-m and CSB-p) in the ratio 1:1 and were characterised by means of FTIR, UV, XRD and SEM. The thermal dehydration and degradation kinetics of all these Schiff bases were studied using different isoconversional and maximum rate (peak) methods, viz. Kissinger–Akahira–Sunose (KAS), Tang, Starink, Flynn–Wall–Ozawa (FWO) and Bosewell from DSC data and the thermal stability from TG. The activation energy values of thermal dehydration and degradation reactions obtained from isoconversional methods of FWO and Bosewell are slightly higher than that obtained from other methods. All the isoconversional and maximum rate (peak) methods yielded consistent values of E _α for both the dehydration and degradation reactions and is in the order CSB-o < CSB-m < CSB-p. The Schiff bases observed (from TG) the same order of thermal stability.     

Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles coated by new functionalized tetraaza-2,3 dialdehyde micro-crystalline cellulose: synthesis,characterization, and catalytic application for degradation of Acid Yellow 17

In this study, we developed an original approach for preparing cellulose-coated magnetite nanoparticles (NPs). Two novel Schiff bases (PDA-g-DAC) and [Bz-(PDA-g-DAC)] were synthesized via condensation reactions of periodate oxidized micro-crystalline cellulose (DAC) with o-phenylene diamine (PDA) to obtain its azomethine derivative with 85% yield. Subsequently, the functionalization of (PDA-g-DAC) with benzil (Bz) yields the tetraaza macrocycle [Bz-(PDA-g-DAC)]. The physicochemical characterization of the condensation products was performed using ¹³CNMR, FTIR, ATG, DSC, and X-ray diffraction techniques. Magnetic nanomaterial-based Schiff base cellulose was successfully prepared using in situ chemical co-precipitation of coordinated ferric and ferrous ions in cellulose Schiff base matrix under optimized conditions, and then, its magnetic properties were characterized. The results demonstrated that the Fe₃O₄ NPs coated with [Bz-(PDA-g-DAC)] were homogeneously coated in the matrix under ultrasonic irradiation with the saturation magnetization of 69.50 emu g^?1. In addition, XRD line broadening analysis showed that the average particle size of the NPs was 37.3 nm. Furthermore, FTIR spectra demonstrated that [Bz-(PDA-g-DAC)] concavity was anchored to magnetite Fe₃O₄ NPs through azomethine groups. Vibrating sample magnetometry (VSM) of [Bz-(PDA-g-DAC)@Fe₃O₄] magnetic nanocomposite samples showed the typical behavior of ferromagnetism. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation. Activity results revealed that the prepared [Bz-(PDA-g-DAC)@Fe₃O₄] catalyst shows the maximum activity for degradation of Acid Yellow 17 (AY17) compared to other prepared catalysts. After degradation reaction, the [Bz-(PDA-g-DAC)@Fe₃O₄] catalyst was recovered from the reaction mixture via an external magnet and used for further five consecutive cycles with excellent catalytic activity, successively, which was comparable to the fresh catalyst. The catalyst degradation efficiency and its easy separation exhibited that [Bz-(PDA-g-DAC)@Fe₃O₄] catalyst is a promising material for the removal of AY17 from aqueous solutions in green chemistry perspectives.     

Acetoacetoxy functionalized natural rubber latex capable of forming cross-linkable film under ambient conditions

This work demonstrates that natural rubber (NR) latex particles containing acetoacetoxy (AcAc) groups are able to undergo cross-linking upon film formation at ambient temperature by reaction with glutaraldehyde (GTA). Natural rubber latex grafted with poly(acetoacetoxyethyl methacrylate) (NR-g-PAAEM) was synthesized by seeded emulsion polymerization, using benzoyl peroxide (BPO) as an initiator in free radical polymerization. The degree of grafting of PAAEM in the graft copolymers was evaluated by ¹H NMR technique. Transmission electron microscope (TEM) was used for investigation the particle morphology of the grafted NR latex. Since the AcAc groups are intentionally attached to the NR particles providing sites of cross-linking at ambient temperature, the cross-linking ability of these sites by reaction with GTA was then investigated. The results revealed that the latex film of NR-g-PAAEM with the addition of GTA had a much higher tensile strength in comparison with the film without GTA. The surface morphology of the NR-g-PAAEM latex film formed in the absence and presence of the GTA cross-linker was also investigated using atomic force microscopy (AFM). By GTA addition into the NR-g-PAAEM latex before film formation, an increase in the root-mean-square (RMS) roughness of the surface of the latex film was observed. Moreover, it was also observed that the NR-g-PAAEM films with the addition of GTA had higher activation energy for thermal degradation than that without the cross-linker. This confirms that the cross-linking reaction took place in the NR-g-PAAEM latex film as a result of its reaction with the GTA.     

Bio-/Environment-Friendly Cationic Gemini Surfactant as Novel Corrosion Inhibitor for Mild Steel in 1 M HCl Solution

Bio-/environment-friendly cationic gemini surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy)dichloride, referred to as 16-E2-16, was synthesized and characterized. Corrosion inhibition effects of 16-E2-16 on mild steel (MS) surface in 1 M HCl solution at 30, 40, 50 and 60 °C were evaluated using gravimetric analysis, potentiodynamic polarisation and electrochemical impedance spectroscopy measurements. The nature of the protective inhibitor film formed on the MS surface was analysed by SEM, EDAX and FT-IR, while TGA was used to assure the thermal behaviour and stability of the film at high temperature. The formation of [inhibitor-Fe²⁺] on the surface of MS was confirmed by UV–visible spectroscopy. The inhibition efficiency of the studied inhibitor increased with increasing concentration and solution temperature. The compound behaved as a mixed type inhibitor and acted by blocking the electrode surface by means of adsorption obeying the Langmuir adsorption isotherm. Surface active properties and corrosion inhibition effects of 16-E2-16 in the presence of inorganic (NaI) and organic (NaSal) salts were also investigated and are discussed. Density functional theory calculations have been carried out to correlate the efficiency of the compound with its intrinsic molecular parameters.     

A novel 1,8-naphthalimide green fluorescent dye and its corresponding intrinsically fluorescent polyurethane latexes

A novel green fluorescent dye, 4-hexylamino-N-(2-hydroxy-1-hydroxymethylethyl)-1,8-naphthalimide (AHHNA), was designed and synthesized, and then used as a chain extender to prepare a series of intrinsically green fluorescent polyurethane (PU) latexes. The chemical structure of AHHNA and the properties of the fluorescent PU latexes and their films were characterized. It was found that the UV–Vis and the fluorescent spectra of the PUs remained fairly consistent with AHHNA, and the fluorescence emitting capacity of 1,8-naphthalimide group was enhanced by covalently bonding AHHNA onto the PU chain. The amount of AHHNA used in the latex preparation had no obvious effect on the latex colloid properties including particle size, poly index, and zeta potential. Results showed that the color difference (ΔE) and the extraction rate (R _e) of the intrinsically fluorescent PU latex film were 5.72% and 3.1%, respectively, while the ΔE and R _e of the extrinsically fluorescent PU latex film were 8.31% and 84.7%, respectively, indicating that the light fastness and the solvent fastness of the intrinsically fluorescent PU latex film were much better than those of the extrinsically fluorescent PU latex film.     

Synthesis,Characterization and Surface Properties of Amidosulfobetaine Surfactants Bearing Odd-Number Hydrophobic Tail

Three amidosulfobetaine surfactants were synthesized namely: 3-(N-pentadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2a); 3-(N-heptadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2b), and 3-(N-nonadecanamidopropyl-N,N-dimethyl ammonium) propanesulfonate (2c). These surfactants were prepared by direct amidation of commercially available fatty acids with 3-(dimethylamino)-1-propylamine and subsequent reaction with 1,3-propanesultone to obtain quaternary ammonium salts. The synthesized surfactants were characterized by IR, NMR and mass spectrometry. Thermogravimetric analysis (TGA) results showed that the synthesized surfactants have excellent thermal stability with no major thermal degradation below 300 °C. The critical micelle concentration (CMC) values of the surfactants 2a and 2b were found to be 2.2 × 10^?4 and 1.04 × 10^?4 mol/L, and the corresponding surface tension (γ_CMC) values were 33.14 and 34.89 mN m^?1, respectively. The surfactants exhibit excellent surface properties, which are comparable with conventional surfactants. The intrinsic viscosity of surfactant (2b) was studied at various temperatures and concentrations of multi-component brine solution. The plot of natural logarithm of relative viscosity versus surfactant concentration obtained from Higiro et al. model best fit the surfactant behavior. Due to good salt resistance, excellent surface properties and thermal stability, the synthesized surfactant has potential to be used in various oil field applications such as enhanced oil recovery, fracturing, acid diversion, and well stimulation.     

Second-Order NLO Active Heterotrimetallic Schiff Base Metallopolymer

The new ionic heterotrimetallic unsymmetrically-substituted Schiff base complex [Ni{(η ⁵-Cp)Fe(η ⁵-C₅H₄)-C(=O)CH=C(4-HO-C₆H₄)NCH₂CH₂N=CH-(2-O-(η ⁶-C₆H₄)Ru(η ⁵-Cp*)}][PF₆] (3; Cp = C₅H₅ and Cp* = C₅(CH₃)₅) was prepared in 86% yield by a one-pot procedure by mixing equimolar amounts of 4-hydroxyphenyl functionalized ferrocenylenaminone 1, the organometallic aldehyde [(η ⁵-Cp*)Ru(η ⁶-2-HO-C₆H₄CHO)][PF₆] (2) and nickel(II) acetate tetrahydrate in refluxing ethanol for 2 h. Its corresponding side-chain metallopolymer 4 was synthesized by reacting the organometallic-inorganic hybrid 3 with polyacrylic acid (DP = 25) in DMF at 110 °C for 48 h with an equimolar quantity of N,N′-dicyclohexylcarbodiimide and a catalytic amount of 4-dimethylaminopyridine. The new complex 3 was characterized by FT-IR and multidimensional NMR spectroscopy, elemental analysis and mass spectrometry. Single crystal X-ray diffraction analysis of 3 showed that the ferrocenyl and [(η ⁵-Cp*)Ru]⁺ units exhibit an anti-conformation and are almost coplanar with the unsymmetrical Schiff base complex fragment, while the 4-HO-C₆H₄ plane is almost perpendicular. The four-coordinate Ni^II metal ion adopts a square planar geometry, with two nitrogen and two oxygen donor atoms that are mutually trans. Size-Exclusion Chromatography established that metallopolymer 4 is formed of approximately three pendant ionic trimetallic units, while Differential Scanning Calorimetry and Thermal Gravimetric Analysis indicated that 3 and 4 are thermally stable with decomposition temperatures that exceed or border to 250 °C. Harmonic Light Scattering measurements at 1.91 µm incident wavelength showed that compounds 3 and 4 exhibit rather high second-order nonlinear responses, with hyperpolarizability β _1.91 values strongly increasing on passing from the monomeric unit 3 to its metallopolymeric counterpart 4.     

A high molecular weight acrylonitrile copolymer prepared by mixed solvents polymerization: II. effect of DMSO/water ratios on polymerization and stabilization

A bifunctional comonomer β-methylhydrogen itaconate was synthesized to prepare high molecular weight poly [acrylonitrile-co-(β-methylhydrogen itaconate)] [P (AN-co-MHI)] by mixed solvents polymerization, which was used as carbon fiber precursor instead of acrylonitrile terpolymers. The effect of dimethyl sulfoxide (DMSO)/deionized water ratios on the polymerization, structure and stabilization of P (AN-co-MHI) was studied by elemental analysis, UV-Visible Spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The highest viscosity-average molecular weight (76.72 × 10⁴ g/mol) of P(AN-co-MHI) was obtained in the mixed solvents of DMSO/deionized water = 10/90 (wt/wt) due to the zero chain transfer constant of deionized water for radical ~ ~ ~AN·, which is 10 times larger than that of P(AN-co-MHI) copolymers prepared in DMSO solution polymerization under the same conditions and is beneficial to improving the tensile strength of resulting carbon fiber. The composition of P(AN-co-MHI) was controlled by the ratio of DMSO/deionized water in the mixed solvents, it is attributed to the changes of AN/MHI ratio taking part in the polymerization reactions, which is caused by the different solubility of AN in the mixed solvents. From elemental analysis and FTIR studies, it can be found out that the content of MHI in P(AN-co-MHI) copolymer becomes larger with the increase of DMSO content in the mixed solvents. The FTIR, XRD and DSC results show that the stabilization of P(AN-co-MHI) copolymer was significantly improved by MHI compared with PAN homopolymer and poly (acrlonitrile-methyl acrylate-acrylic acid) terpolymer, such as larger extent of stabilization, lower initiation temperature and smaller E _a of cyclization, which is beneficial to preparing high performance carbon fiber.     

Bioengineering functional copolymers: synthesis and characterization of poly(<Emphasis Type="Italic">N</Emphasis>-isopropyl acrylamide-<Emphasis Type="Italic">co</Emphasis>-3,4-2H-dihydropyran)s

Novel bioengineering copolymers were synthesized by radical copolymerization of N-isopropylacrylamide (NIPA) and 3,4-2H-dihydropyran (DHP) with 2,2′-azobisisobutyronitrile as an initiator in acetone solution at 70 °C under nitrogen atmosphere. Structure, tacticity and compositons of the copolymers prepared in a wide range of monomer feed were confirmed by FTIR, ¹H{¹³C} NMR-DEPT and elemental analyses. The monomer reactivity ratios (r ₁ and r ₂) were detected using known two methods: r ₁ (NIPA)?=?1.25 and r ₂?=?0.035 (DHP), and r ₁ (NIPA) ?=?0.97 and r ₂?=?0.022 (DHP) by Kelen-Tüdös and Jaacks methods, respectively. It was demonstrated that the studied monomer pair has a tendency to form H-bonding beween amide/ether groups through ?NH...O< complexation which played an important role in the stereoselective chain growth, and significant decrease of allyl degradative chain transfer reactions. This phenomenon is also confirmed by the observed relatively high molecular weights of copolymers (M _v ). The synthesized water-soluble stimuli-responsive poly(NIPA-co-DHP)s exhibit thermal stability, higher glass-transition temperature, polyelectrolyte, pH- and temperature-sensitive behavior and can be attributed to the class of bioengineering functional copolymers useful for various bio- and gene-engineering, and drug delivery applications.     

Synthesis,Surface Activities and Toluene Solubilization by Amine-oxide Gemini Surfactants

A series of amine-oxide gemini surfactants featuring amide groups [N, N’-dimethyl-N, N’-bis(2-alkylamideethyl)-ethylenediamine oxide (alkyl = C₁₁H₂₃, C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅)] have been synthesized via a three-step synthetic route, and their chemical structures were confirmed by mass spectra, FTIR and ¹H-NMR spectra. The surface activities of these compounds have been measured. The results show that these synthesized amine-oxide gemini surfactants reduced the surface tension of water to a minimum value of approximately 26.91 mN m^?1 at a concentration of 2.92 × 10^?5mol L^?1. Furthermore, their critical micelle concentration (CMC) values and solubilization of toluene decrease with an increase of the hydrophobic chain length from 12 to 18. Isoelectric point measurements revealed that their pI values range from 4.0 to 10.5.     

Optimization of controlled ring-opening polymerization of <Emphasis Type="SmallCaps">l</Emphasis>-lactide to hydroxyl terminated polylactides using zinc acetate catalyst

Hydroxyl terminated polylactide polymers with number of average molecular weights (M _n ) varying from 1625 to 3459 g mol^?1 were synthesized by ring opening bulk polymerization of lactide in the presence of zinc acetate being a potent catalyst. The use of 1,4 butanediol (BDO) initiator leads to hydroxyl terminated polylactides, thus excellent precursors for shape-memory biodegradable polyurethanes. Different reaction conditions employed for the synthesis of hydroxyl terminated polylactide polymers via activated monomer mechanism may result in differences in M _n , percentage mass conversion and percentage degree of crystallinity (%χ _c ) of the product. Influence of process parameters, i.e. catalyst concentration, initiator concentration, reaction temperature and time on characteristics of hydroxyl terminated polylactides was studied. These polymers were characterized by Nuclear Magnetic Resonance (¹H-NMR) spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and X-ray diffraction (XRD) techniques. FTIR and ¹H-NMR confirmed the formation of hydroxyl terminated polylactides. M _n was determined by ¹H-NMR, GPC and end group analysis. %χ _c was calculated from XRD spectra. Maximum mass conversion, M _n and %χ _c were observed at 5 mol% SnOct₂ and 5 mol% BDO concentration. At optimum temperature of 145 °C, these characteristics improved linearly with polymerization time up to 6 h and declined thereafter.     

Synthesis and Characterization of pH-Responsive Organic–Inorganic Hybrid Material with Excellent Catalytic Activity

Poly(N-isopropylmethacrylamide-co-methacrylic acid) [p(NipAam-Mac)] microgels were synthesized and used as microreactors to fabricate silver nanoparticles. Pure and hybrid microgels were characterized using Ultraviolet–Visible (UV/Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). Catalytic activity of hybrid microgels and mechanism of catalysis by this system was explored using different reaction conditions. At the same temperature, apparent rate constant (k_app) was found to be varied from 0.0414 to 0.7852 min^?1 by increasing the concentration of NaBH₄ from 2.49 to 22.41 mM at constant concentration of substrate and catalyst. However upon extra increase in concentration of NaBH₄ from 22.41 to 37.35 mM reduced the value of k_app to 0.2178 min^?1. Likewise, the value of k_app was found to be increased from 0.1242 to 0.5495 min^?1 with increasing the concentration of 4-nitrophenol [Para-nitrophenol (p-Np)] from 0.063 to 0.079 mM keeping other parameters constant. Further increase in concentration of p-Np caused decline in the value of k_app. Kinetic data reveals that catalytic reduction of p-Np obeys Langmuir–Hinshelwood mechanism and p-Np is converted to p-Ap on the surface of the silver nanoparticles passing through various reaction intermediates.     

Curing kinetics of epoxy cured by cardanol-based phenalkamines synthesized from different polyethylenepolyamines by Mannich reaction

Phenalkamines with different structures are expected to affect the curing reaction of epoxy, yet the exact mechanism remains to be elucidated. In this study, four cardanol-based phenalkamines (named PK1, PK2, PK3, and PK4, respectively), synthesized from ethylenediamine, diethylenetriamine, triethylenetetramine, and pentaethylenehexamine, were used as curing agents in diglycidyl ether of bisphenol A (DGEBA) epoxy system. The phenalkamines were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and time-of-flight secondary ion mass spectrometry. The curing behaviors and kinetics were investigated by non-isothermal differential scanning calorimetry, and the activation energies of the reactions (E _α ) were determined using Kissinger–Akahira–Sunose (KAS) and Starink methods. The results indicate a similar curing mechanism for all four phenalkamines. All E _α values remain almost constant in the range of 0.05 ≤ α ≤ 0.6, and increase dramatically after α > 0.6 due to greater viscosity of the reaction systems. The diffusion of reactive groups plays an increasingly important role in determining the curing kinetics. In addition, DGEBA/PK1 and DGEBA/PK2 have lower initial E _α values than DGEBA/PK3 and DGEBA/PK4, because PK1 and PK2 have lower viscosity than PK3 and PK4. When α is high, DGEBA/PK1 and DGEBA/PK2 have higher E _α values than DGEBA/PK3 and DGEBA/PK4, because more tertiary amine groups can be formed in the reactions between the epoxy and secondary amine groups in the DGEBA/PK3 and DGEBA/PK4 systems, which catalyze the curing reaction and it thus lowers energetic barrier.     

A Comprehensive Study on the Synthesis and Micellization of Disymmetric Gemini Imidazolium Surfactants

Two groups of disymmetric Gemini imidazolium surfactants, [C₁₄C₄C _m im]Br₂ (m = 10, 12, 14) and [C _m C₄C _n im]Br₂ (m + n = 24, m = 12, 14, 16, 18) surfactants, were synthesized and their structures were confirmed by ¹H NMR and ESI–MS spectroscopy. Their adsorption at the air/water interface, thermodynamic parameters and aggregation behavior were explored by means of surface tension, electrical conductivity and steady-state fluorescence. A series of surface activity parameters, including cmc, γ _cmc, π _cmc, pC ₂₀, cmc/C ₂₀, Γ _max and A _min, were obtained from surface tension measurements. The results revealed that the overall hydrophobic chain length (N _c) for [C₁₄C₄C _m im]Br₂ and the disymmetry (m/n) for [C _m C₄C _n im]Br₂ had a significant effect on the surface activity. The cmc values decreased with an increase of N _c or m/n. The thermodynamic parameters of micellization (ΔG _m ^θ , ΔH _m ^θ , ΔS _m ^θ ) derived from the electrical conductivity indicated that the micellization process of [C₁₄C₄C _m im]Br₂ and [C _m C₄C _n im]Br₂ was entropy-driven at different temperatures, but the contribution of ΔH _m ^θ to ΔG _m ^θ was enhanced by increasing N _c or m/n. The micropolarity and micellar aggregation number (N _agg) were estimated by steady-state fluorescence measurements. The results showed that the surfactant with higher N _c or m/n can form larger micelles, due to a tighter micellar structure.     

Preparation of high surface area mesoporous nickel oxides and catalytic oxidation of toluene and formaldehyde

Mesoporous nickel oxide (NiO) nanoparticles were synthesized by the thermal decomposition reaction of Ni(NO₃)₂·9H₂O using oxalic acid dihydrate as the mesoporous template reagent. The pore structure of nanocrystals could be controlled by the precursor to oxalic acid dihydrate molar ratio, thermal decomposition temperature and thermal decomposition time. The structural characteristic and textural properties of resultant nickel oxide nanocrytals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption–desorption isotherm and temperature programmed reduction. The results showed that the most excellently mesoporous nickel oxide particles (m-Ni-1-4) with developed wormlike pores were prepared under the conditions of the mixed equimolar precursor and oxalic acid and calcined for 4 h at 400 °C. The specific surface area and pore volume of m-Ni-1-4 are 236 m² g^?1 and 0.42 cm³ g^?1, respectively. Over m-Ni-1-4 at space velocity = 20,000 mL g^?1 h^?1, the conversions of toluene and formaldehyde achieved 90 % at 242 and 160 °C, respectively. It is concluded that the reactant thermal decomposition with oxalic acid assist is a key step to improve the mesoporous quality of the nickel oxide materials, the developed mesoporous architecture, high surface area, low temperature reducibility and coexistence of multiple oxidation state nickel species for the excellent catalytic performance of m-Ni-1-4.     

Novel amphiphilic temperature responsive graft copolymers PCL-<Emphasis Type="Italic">g</Emphasis>-P(MEO<Subscript>2</Subscript>MA-<Emphasis Type="Italic">co</Emphasis>-OEGMA) via a combination of ROP and ATRP: synthesis,characterization, and sol-gel transition

A series of well-defined novel amphiphilic temperature-responsive graft copolymers containing PCL analogues P(αClεCL-co-εCL) as the hydrophobic backbone, and the hydrophilic side-chain PEG analogues P(MEO₂MA-co-OEGMA), designated as P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) have been prepared via a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The composition and structure of these copolymers were characterized by ¹H NMR and GPC analyses. The self-assembly behaviors of these amphiphilic graft copolymers were investigated by UV transmittance, a fluorescence probe method, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results showed that the graft copolymers exhibited the good solubility in water, and was given the low critical temperature (LCST) at 35(±1) °C, which closed to human physiological temperature. The critical micelle concentrations (CMC) of P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) in aqueous solution were investigated to be 2.0 × 10^?3, 9.1 × 10^?4 and 1.5 × 10^?3 mg·mL^?1, respectively. The copolymer could self-assemble into sphere-like aggregates in aqueous solution with diverse sizes when changing the environmental temperature. The vial inversion test demonstrated that the graft copolymers could trigger the sol-gel transition which also depended on the temperature.     

Effect of different structured POSS/GMA-containing copolymers on the morphology of porous coating by breath-figures method

Polyhedral oligomeric silsesquioxane (POSS) and glycidyl methacrylate (GMA) are used to synthesize linear L-(PGMA-b-MA-POSS), dicephalous D-(PGMA-b-MA-POSS)₂, and four-armed T-(PGMA-b-MA-POSS)₄ through atom transfer radical polymerization (ATRP). These different structured POSS/GMA-containing copolymers are applied to build the porous films through breath-figures (BF) method. L-(PGMA-b-MA-POSS) is easy to form the ordered porous BF film, and T-(PGMA-b-MA-POSS)₄ tends to form well-distributed BF film due to its high segment density which is beneficial to stabilize water drop. It is proven that solvent has a great effect on the morphologies of BF film. The perfect BF film is developed in the relatively wet atmosphere as 5–8 μm diameter of pores casted in THF and 2–4 μm diameter of pores casted in CH₂Cl₂ with regular morphology. The developed BF film has superior stability than the film developed in natural conditions due to the shorter stable balancing time. Therefore, it is believed that the obtained porous films show great potential in coating application.     

Evaluation of Host-Derived Volatiles for Trapping <Emphasis Type="Italic">Culicoides</Emphasis> Biting Midges (Diptera: Ceratopogonidae)

Culicoides biting midges (Diptera: Ceratopognidae) cause pain and distress through blood feeding, and transmit viruses that threaten both animal and human health worldwide. There are few effective tools for monitoring and control of biting midges, with semiochemical-based strategies offering the advantage of targeting host-seeking populations. In previous studies, we identified the host preference of multiple Culicoides species, including Culicoides impunctatus, as well as cattle-derived compounds that modulate the behavioral responses of C. nubeculosus under laboratory conditions. Here, we test the efficacy of these compounds, when released at different rates, in attracting C. impunctatus under field conditions in Southern Sweden. Traps releasing 1-octen-3-ol, decanal, phenol, 4-methylphenol or 3-propylphenol, when combined with carbon dioxide (CO₂), captured significantly higher numbers of C. impunctatus compared to control traps baited with CO₂ alone, with low release rates (0.1 mg h^?1, 1 mg h^?1) being generally more attractive. In contrast, traps releasing octanal or (E)-2-nonenal at 1 mg h^?1 and 10 mg h^?1 collected significantly lower numbers of C. impunctatus than control traps baited with CO₂ only. Nonanal and 2-ethylhexanol did not affect the attraction of C. impunctatus when compared to CO₂ alone at any of the release rates tested. The potential use of these semiochemicals as attractants and repellents for biting midge control is discussed.     

Synthesis,characterization, thermal stability and electrochemical properties of <Emphasis Type="Italic">ortho</Emphasis>-imine-functionalized oligophenol via enzymatic oxidative polycondensation

Ortho-imine functionalized oligophenol was synthesized via enzymatic polymerization of 2-((4-nitrophenylimino)methyl)phenol (NPIMP). Enzymatic polymerization was catalyzed by Horseradish peroxidase (HRP) enzyme and hydrogen peroxide (H₂O₂) oxidizer yielded oligophenol with imine functionality on the side-chain. Effects of various factors including reaction pH, temperature and solvent system on the polymerization were studied. Optimum polymerization with the highest yield (96 %) and number-average molecular weight (M _n = 7300 g/mol, degree of polymerization ≈ 30) was accomplished using equivolume mixture of acetone/pH 7.0 phosphate buffer medium at 35 °C in 24 h under air. Characterization of the resulting oligomer was accomplished by ultraviolet-visible spectroscopy (UV-Vis), fourier transform infrared spectroscopy (FT-IR), ¹H and ¹³C nuclear magnetic resonance (¹H and ¹³C NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), cyclic voltammetry (CV) and gel permeation chromatography (GPC). The polymerization involved elimination of hydrogen from NPIMP, and the oligomer possessed phenolic –OH end groups. The oligomer backbone was composed of oxyphenylene and phenylene repeat units. The optical band gaps (Eg) of NPIMP and oligo(NPIMP) were measured as 3.21 and 3.39 Eg, respectively. Thermal stability of the oligo(NPIMP) was also found to be relatively high, and lost 5 % of its mass at 175 °C and lost 50 % of its mass at 600 °C.