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An eco-friendly and economical approach for the photocatalytic oxidation of organic inter-mediates by air under mild conditions is highly desirable in green and sustainable chemistry, where the photogeneration of active oxygen species plays a key role in improving conversion efficiency and selectivity. By using pyridinium derivatives as molecular mediators for electron transfer and energy transfer, the simultaneous activation of O2 from air into superoxide radicals and singlet oxygen species can be achieved, and a photoinduced electron transfer catalytic system for the oxidation of alcohols has been developed. Thus, we have successfully simplified the complicated catalytic system into a single molecular catalyst without any additional noble metals and co-catalysts/additives. The current photocatalytic system shows high catalytic efficiency not only for aromatic alcohols but also for aliphatic alcohols that are generally difficult to undergo aerobic oxidation at room temperature under air atmosphere, representing an ideal photocatalytic platform for green and economical organic syntheses.

This study aims to investigate the effect of pH levels (pH 7.0 and pH 8.1) on binding ability of β-lactoglobulin (β-LG) with lycopene (LYC) and elucidate interaction mechanisms using multi-spectroscopy and molecular docking study. β-LG at pH 8.1 showed a stronger binding affinity to lycopene than that at pH 7.0 according to binding constant, binding number, energy transfer efficiency, and surface hydrophobicity. Lycopene bound to protein mainly by van der Waals force in the form of static quenching mode and preferred to interact with β-LG at the top of barrel for both pH levels. Molecular dynamic simulation revealed that β-LG/LYC complex at pH 8.1 was more stable than at pH 7.0. β-LG/LYC complexes formed at pH 8.1 showed significantly higher ABTS radical scavenging activity than samples at pH 7.0 (p 0.05). Data obtained may contribute valuable information for preparing a whey protein-based delivery system for lycopene.

A Zn(II)-mediated pyridinium-bearing coordination polymer has been successfully synthesized and structurally characterized. The title compound exhibits rapid photochromic properties due to proper structural arrangement of the electron donor and acceptor for PET reaction. Besides, it also displays luminescence switching under the irradiation of 365 nm light.

Based on 1,3-bis(2-methylbenzimidazole)propane (L1), 1,4-bis(2-methylbenzimidazole)butane (L2) and 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene (L3) with aromatic carboxylic acids, three cocrystals, [(H2L1)2+·2(H2btrc)1−] (1), [(H2L2)2+·(H2btec)2−·2H2O] (2) and [(H2L3)2+·(H2btec)2−] (3) (H3btrc = 1,2,4-benzenetricarboxylic acid, H4btec = 1,2,4,5-benzenetetracarboxylic acid) were synthesized in solution and obtained by slow evaporation. All solid products were characterized by elemental analyses, IR spectra, and single-crystal X-ray diffraction. Components of the crystalline phase have also been investigated in terms of Hirshfeld surfaces. The bis(benzimidazole) derivatives interlinked with aromatic carboxylates through intermolecular H-bonding and π–π interactions generate diverse 3D supramolecular networks for 1, 2, and 3. The Hirshfeld surfaces and 2D fingerprint plots of three cocrystals show that 1–3 are stabilized by N–H···O, O–H···O, and π–π intermolecular interactions. The thermal stabilities and photoluminescence properties for cocrystals 1–3 were presented in the solid state.

Herein, a nickel coordination polymer (CP 1), {Ni(1,4-bib)1.5(TPA-Cl2)·H2O}n (1,4-bib = 1,4-bis(1H-imidazol-1-yl)benzene, H2TPA-Cl2 = 2,5-dichloro-terephthalic acid), has been synthesized under solvothermal conditions. The structure of CP 1 is a 3D 3-fold interpenetrating framework with the sqc12 topology. The thermal stability and luminescence properties of CP 1 were investigated. Scanning electron microscopy (SEM) images of this material display that it possesses an irregular block 3D structure. Interestingly, CP 1 can serve as a multifunctional material via its luminescence sensing, electrochemical sensing, and photocatalytic properties. The experimental results indicate that CP 1 is an efficient luminescent sensor for the detection of Fe3+ ions in an aqueous solution. In addition, CP 1 exhibits a sensitive and rapid electrochemical response to nitrite ions in water solution. The photocatalytic activities of CP 1 were evaluated in the degradation of different dye contaminants (MB, RhB, and MO), and the results demonstrate that its photocatalytic efficiency for the degradation of MB is highest (92.1% for MB, 85.7% for RhB, and 86.2% for MO). The effects of different dyes, different powers of UV light, and different amounts of catalyst CP 1 on the photocatalytic efficiency were also explored. Finally, the mechanism of the luminescence quenching effect toward Fe3+ ions, electroreduction of nitrite ions, and photocatalytic degradation of different dyes have been investigated in detail.

The hydrothermal reactions of 1,2,4,5-cyclohexanetetracarboxylic acid (H4L) with CoCl2·2H2O and rigid or semi-rigid bis(imidazole) ligands were able to generate two Co(ii) coordination polymers (CPs), {[Co5(L)2(1,4-bimb)(μ3-OH)2(H2O)8]·2H2O}n (1), {[Co(L)0.5(1,4-bib)]·H2O}n (2) (1,4-bimb = 1,4-bis(imidazol-1-ylmethyl)benzene, 1,4-bib = 1,4-bis(1H-imidazol-1-yl)benzene). CPs 1 and 2 were structurally characterized by elemental analysis, IR spectroscopy, X-ray powder diffraction and single crystal X-ray diffraction. CP 1 features a 3D 3,3,4,4,5-connected framework with an unprecedented {42·8·102·12}{43·6·86}2{43}2{46}2{62·8}2 topology, which represents the first example of CPs with such a topology. CP 2 possesses a three-fold interpenetration 3D framework with mog topology. The distinct structures of the two CPs may result from diverse coordination modes of the (L)4- ligands and different structural characteristics of rigid or semi-rigid N-donor ligands. The thermal stabilities, photoluminescence properties and electrochemical behavior in the solid state for CPs 1 and 2 have been investigated. The photophysical studies indicated that CPs 1 and 2 are potential semiconductive materials. Moreover, both CPs 1 and 2 show high photocatalytic efficiency for the degradation of methylene blue (MB) under UV light irradiation and exhibit good stability and recyclability. A possible photocatalytic mechanism is speculated by introducing t-butyl alcohol (TBA) as a widely used ˙OH scavenger.

Surface modification based on a photo-induced electron transfer (PET) reaction in a pyridinium-decorated MOF material was found to be effective in regulating adsorption capacity. The current system enables the adsorption behavior to be manipulated based on variable affinity toward guest molecules through the redistribution of charge population with the preservation of the original pore structure, which is different from the prevalent approaches depending on photoinduced changes in molecular configurations of the pore backbone.

Photodynamic behavior controlled by the synergy of electron transfer and charge transfer has been characterized in two regioisomeric pyridinium-bearing coordination polymers (Cd-Bip and Cd-Bpy) with the help of a smart charge-distribution-related isoreticular strategy. Because it is relatively weak, the charge-transfer interaction between adjacent 2D networks in Cd-Bip can be easily perturbed by photoinduced electron transfer under irradiation with 365 nm light, and then successfully drives the occurrence of photodynamic behavior. In contrast, lower energy 450 nm light is absorbed to a lesser extent, and can only induce a low degree of electron transfer, which is insufficient to actuate operation of this photodynamic behavior in Cd-Bip.

Recent studies have shown that neonicotinoids in pollen and honey (collected by honeybees) are likely to pose risks to honeybees. However, data on the integrated residue and spatial-temporal variation of neonicotinoids from noncrop plants, the principle sources of pollen for honey bees, are very limited, especially in China. In this study, we employed a novel assessment method based on the relative potency factor to calculate the integrated residue of seven neonicotinoids in pollen and honey samples collected from noncrop plants in 12 stations of Zhejiang province in three consecutive months. The integrated concentration of neonicotinoids (IMIRPF) ranged from no detected (ND) to 34.93 ng/g in pollen and ND to 8.51 ng/g in honey. Acetamiprid showed the highest detection frequency of 41.7%, followed by clothianidin (33.3%) and dinotefuran (22.2%). The highest IMIRPF occurred in April for stations in the fringe areas of Zhejiang province, whereas for stations in the central areas of Zhejiang province, the IMIRPF in May was relatively higher than the other two months. In terms of spatial change, the pollution variation of pollen samples in Lin'an—Tonglu—Pujiang was relative highly polluted—lightly polluted—highly polluted. For honey samples, spatial variation showed a single trend, and peak values were found in Wenzhou, which may be attributed to the local climate and farming practices. This fundamental information will be helpful to understand the effects of neonicotinoids on honeybees foraging habits.

We prepared intercalated organic montmorillonite (OMMT) from a pristine MMT and long-alkyl-chain quaternary ammonium salts (LACQAS). X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analyses revealed that the amount, carbon atoms, and alkyl chains of LACQAS influenced the large value of d(001) of OMMT significantly. The d(001) stabilized at 100–150 mmol·(100 g)-1 of LACQAS/MMT. The single LACQAS cations arranged in the form of a lateral layer or half-paraffin-type molecular structure between MMT layers, whereas the dual and triple LACQAS cations arranged in the form of a paraffin-type molecular structure. The pyrolysis temperature and maximum pyrolysis rate of OMMT increased greatly compared with those of MMT. The thermal weight loss of MMT was caused by the removed absorbed and structural water, whereas that of OMMT was by the pyrolysis of LACQAS. With the help of the Agrawal integral equation, the pyrolysis kinetics of MMT and OMMT were obtained using a trial-and-error method.

Three coordination polymers, namely {[Ni(L1)(nip)(H2O)]·2H2O} n (1), [Co(L2)(tbip)] n (2), and {[Co2(L3)2(bptc)]·3H2O} n (3) (L1 = 1,4-bis(5,6-dimethylbenzimidazole)butane, L2 = 1,4-bis(5,6-dimethylbenzimidazole)-2-butylene, L3 = 1,3-bis(5,6-dimethylbenzimidazole)propane, H2nip = 5-nitro-isophthalic acid, H2tbip = 5-tert-butyl-isophthalic acid, H4bptc = biphenyl-3,3′,4,4′-tetracarboxylic acid), have been synthesized under hydrothermal conditions and characterized by physicochemical and spectroscopic methods as well as by single-crystal X-ray diffraction analysis. Complexes 1 and 2 both feature a two-dimensional (4,4) layer with (44 × 62) topology. Complex 3 possesses a uninodal 4-connected 2D htb network. The fluorescence spectra and catalytic properties of the complexes for the degradation of methyl orange by sodium persulfate in a Fenton-like process are reported.

Two Cu(i) cyanide coordination polymers (CPs), namely, [Cu2(L1)(CN)2]n (1) and [Cu2(L2)(CN)2]n (2) (L1 = 4,4'-bis(2-methylbenzimidazol-1-ylmethyl)biphenyl, L2 = 4,4'-bis(5,6-dimethylbenzimidazol-1-ylmethyl)biphenyl) were synthesized and structurally characterized by single crystal X-ray diffraction, IR spectroscopy, X-ray powder diffraction and elemental analysis. The cyanide ligands in these CPs are generated in situ from the C-C bond cleavage of acetonitrile under solvothermal conditions, which is environmentally friendly and used conveniently. CP 1 features a three-fold interpenetration 3D framework consisting of Cu10(CN)6(L1)4 rings, which represents the first investigation on introducing bis(benzimidazole) ligands into copper(i) cyanide CPs with ThSi2 topology, while CP 2 exhibits a two-dimensional (6,3) layered structure containing Cu6(CN)4(L2)2 rings. The thermal stabilities, and photoluminescence and electrochemical behavior in the solid state of CPs 1 and 2 have been investigated in detail. Moreover, both CP 1 and CP 2 manifest promising photocatalytic activities (photodegradation efficiency using CP 1 is 90.8% and using CP 2 is 87.2%) for the degradation of methylene blue (MB) under UV light irradiation. A possible photocatalytic mechanism is suggested by introducing t-butyl alcohol (TBA) as a widely used ˙OH scavenger.

In this study, microwave plasma was used to treat the surface of Pinus yunnanensis wood under the conditions of 220 V of input voltage, 20 μA of filament current, 8.8 mW of output power, 11 mW of reflected power, 2450 MHz of frequency, and 700 Pa of vacuum. The microwave plasma presented very significant treatment effects on the treated surface, even under weak treatment conditions, for example long treatment distance of 120 mm and short treatment time of 60 s. The treated surface showed better surface wettability, and the contact angles on the treated surface measured from deionized water, glycerin, and diiodomethane decreased sharply, even decreased to 0°. The treated surface also presented higher surface free energy, for example, 61.4–62.8 mJ m−2, being greatly improved by microwave plasma compared to that of untreated surface of 46.5 mJ m−2. The bond strength of the treated surface was 7.34 MPa, about 16 % higher than 6.31 MPa for untreated surface. The best treatment effect was obtained for the treatment distance of 120 mm and treatment time of 60–300 s. This technique might be widely used in wood modification and wood processing.

In this study, vinyl acetate, N-hydroxymethyl acrylamide (NMA), and organic montmorillonite intercalated by a dioctadecyl dimethyl ammonium bromide surfactant (MMT-DOAB) were used to prepare exfoliated nanocomposites through in situ polymerization. Wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, power-law function equation, Newtonian fluid flow equation, Cross–Williamson model viscous equation, Hooke's law, and Poisson's ratio equation revealed the structures, dispersion, rheology, and static tensile properties. The exfoliated nanocomposites were pseudoplastic non-Newtonian fluids with good dispersion in water, great storage stability, and high static tensile strength at 6.89–8.15 MPa. The contents of NMA and MMT-DOAB increased with the changes in synthesis precursors, as the calculated molecular weights did.

In this study, we prepared high-performance printable, stretchable electrical conductor from waterborne polyurethane and micro-silver flakes. The solidification and thermal degradation were investigated using differential scanning calorimetry and thermogravimetric analysis methods. The electrical conductor achieved solidification by volatilizing and removing the free water. The thermal degradation mainly happened in the range of 250–450 °C caused by the pyrolysis of the polymeric matrix of polyurethane. The pyrolysis kinetic equations were obtained using the kinetic methods, e.g., dα/dt = e22.16(1 − α)0.78α0.13e(−149.14/RT) for the polyurethane, dα/dt = e22.76(1 − α)0.84α0.11e(−150.69/RT), dα/dt = e21.43(1 − α)0.77α0.06e(−143.77/RT), and dα/dt = e19.06(1 − α)0.75α0.12e(−130.53/RT) for the electrical conductor containing 80, 85, and 90 % mass percentage of micro-silver flakes, where α was the fractional extent conversion at a given time t (or a given temperature T). Their overall order of reaction was 0.91, 0.95, 0.83, and 0.87, respectively, less than 1, demonstrating the thermal degradation was a single, simple reaction.

In this study, a thermal initiator of 1,1-bis(t-hexylperoxy)-3,3,5-trimethyl cyclohexane was introduced to thermally initiate the curing of vinyl ester resin, and then a dynamic differential scanning calorimetry method was applied to investigate the thermally initiated curing procedures. Thermally initiated by the thermal initiator under heating, the end double bonds of vinyl ester resin macromolecules were opened to accomplish the crosslinking, polymerizing, and curing. The increasing thermal initiator advanced the curing procedures and shifted the initial temperature, exothermic peak temperature, and final temperature to a low temperature zone. The curing kinetics of thermally initiated vinyl ester rein was studied using the Ozawa method and deduced by assuming a constant activation energy. The thermally initiated curing kinetic equations, e.g., dα/dt = e30.16(1 − α)2.88α0.01e−106.60/RT, dα/dt = e29.43(1 − α)2.72α0.16e−105.17/RT, dα/dt = e29.43(1 − α)2.85α0.03e−104.48/RT, dα/dt = e29.41(1 − α)2.87α0.01e−104.11/RT, dα/dt = e27.70(1 − α)2.64α0.05e−99.63/RT, and dα/dt = e26.26(1 − α)2.32α0.30e−96.16/RT, respectively corresponding to the weight ratios between the thermal initiator and the vinyl ester resin at 0.5:100, 1:100, 2:100, 3:100, 4:100, and 5:100, were obtained. The increasing thermal initiator significantly influenced the thermally initiated curing kinetic parameters, such as the exothermic peak temperature, the fractional extent conversion, the rate of conversion, the overall order of reaction, the activation energy, the preexponential factor, and the reaction rate constant, and the thermally initiated curing kinetic equations. The data calculated from the kinetic equation agreed well with the experimental data, showing that the Ozawa method could evaluate the curing kinetics effectively.

By adding 2 wt% multi-layer graphene oxide (MGO) to an epoxy resin, the thermal conductivity of the compos- ite reached a maximum, 2.03 times that of the epoxy. The presence of 2 wt%MGO percolating chains leads to an unprece- dentedly sharp rise in energy barrier at final curing stage, but an increased epoxy curing degree (!IR) is observed; however, this !IR difference nearly disappears after aging or thermal annealing. These results suggest that the steep concentration gra- dient of -OH, originated from the 2 wt%MGO percolating chains, exerts the vital driving force on the residual isolated/ trapped epoxy to conquer barrier for epoxy-MGO reaction. A modified Shrinking Core Model customized for the special layered-structure of MGO sheet was proposed to understand the resistance variation during the intercalative epoxy-MGO reaction. It shows that the promoted intercalative crosslinking is highly desirable for further improving the thermal conduc- tivity of the composite, but it meets with increased resistance. Guided by the kinetic studies, targeted optimization on the cure processing strategy was accordingly proposed to promote the intercalative crosslinking, a thermal conductivity, 2.96 times that of the epoxy, was got with only a small amount (30°C) increase of the post-heating temperature.

A biodegradable polyvinyl alcohol and silver nanowires (AgNWs) have been mixed together with a simple one-step blending method to form a hybrid electrical compositor. Super flexible and highly conductive electrical compositors were successfully developed with an AgNWs content of 80%, in which hundreds, even thousands of AgNWs stacked into a “Chrysanthemum petal” order to exhibit high electrical conductivity of 17 390 S cm−1. The high conductivity corresponded to the formation of a large amount of electrically conductive networks and channels. The conductively electrical compositor can be made into various shapes and can be used on any substrate with different curved surfaces because the compositor ink is so stable and can be stored for a long time without other additives. The compositor is expected to have great potential application in flexible electronics, especially in those fields associated with biology, medicine, food, and life.

Nanostructures of a new Co(II) coordination polymer (CP), [Co(Hbibp)(nbta)] n ( 1 ), (bibp = 4,4′-bis(1-imidazolyl)biphenyl, H 3 nbta = 5-nitro-1,2,3-benzenetricarboxylic acid) was synthesized by a sonochemical method. The nano-sized CP 1 was characterized by elemental analysis, IR spectroscopy, X-ray powder diffraction and scanning electron microscopy (SEM). Structural analysis show that CP 1 exhibits a 1D chain structure with a 3-connected SP 1-periodic net (4,4)(0,2) topology, which can be further extended into a 2D supramolecular layer by the N H⋯O hydrogen bond interactions. The thermal stability for CP 1 as bulk and nanoparticles were investigated. The photoluminescence properties and electrochemical behavior for nano-sized CP 1 have also been explored. Moreover, nano-sized CP 1 shows high photocatalytic activities for the degradation of MB under UV irradiation and the photodegradation process is mainly caused by OH radicals. Effects of the sonication time and ultrasonic power on the morphology and size of nanoparticles were studied.

In this study, the exfoliated montmorillonite was prepared through the click chemistry of a propargyl-containing intercalator with singly or multiply azido-functionalized polyhedral oligomeric silsesquioxane nanoparticles. Thermogravimetric analyses revealed that the pyrolysis kinetics had a close relationship to the layered structures, exfoliated structures, and cage-like molecules of polyhedral oligomeric silsesquioxane nanoparticles. The pyrolysis of exfoliated montmorillonite had a mechanism function of Avrami–Erofeev equation, and the kinetic compensation effect equation revealed the pyrolysis.

In this study, we introduced N-hydroxymethyl acrylamide and an organic montmorillonite intercalated by an octadecyl trimethyl ammonium bromide surfactant together into the in situ polymerization of polyvinyl acetate to form exfoliated nanocomposites. Wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, power-law function equation, Newtonian fluid flow equation, Cross-Williamson model viscous equation, Hooke's law, and Poisson's ratio equation revealed the structures, dispersion, rheology, and static tensile properties. The exfoliated nanocomposites were pseudo-plastic non-Newtonian fluids, presented a good dispersion in water, a great storage stability, and a high static tensile strength at 6.78–8.06 MPa.

In this study, we synthesized a poly(N-isopropylacrylamide) (PNIPAm) through the polymerization of N-isopropylacrylamide in distilled water with azodiisobutyronitrile as the initiator and a bisadenine-functionalized poly(ethylene oxide) (A-PEO-A) from the reaction of adenine with a difunctionalized toluenesulfonyl-PEO. When blended together in distilled water, PNIPAm and A-PEO-A formed supramolecular aggregates stabilized through complementary multiple hydrogen bonds between the amide groups of PNIPAm and the adenine units of A-PEO-A. Agrawal integral equation and rheometry revealed the rheological kinetics of supramolecular assemblies, which were influenced significantly by the spherical micelles, large associated aggregates of spherical micelles, network structures, and toroid structures formed in aqueous solutions.

In this study, we used a singly azido-functionalized polyhedral oligomeric silsesquioxane (POSS) derivative and a montmorillonite intercalated by propargyldimethylstearylammonium bromide to prepare an exfoliated montmorillonite through click chemistry. This exfoliated montmorillonite was then introduced into a benzoxazine matrix prepared from paraformaldehyde, aniline, and phenol to form polybenzoxazine/exfoliated clay nanocomposites. Dynamic mechanical analysis, differential scanning calorimetry, and Agrawal integral equation revealed that the glass transition kinetics had a close relationship to the structure, assembly process, and anchoring effect of montmorillonite layers, the compatibility between polybenzoxazine and intercalator, and the methods of dynamic mechanical analysis and differential scanning calorimetry. The polybenzoxazine/exfoliated clay nanocomposites presented the same mechanism function at different weight ratios between polybenzoxazine and exfoliated clay, and the kinetic compensation effect equations revealed the nature of glass transition.

In this study, the montmorillonite (MMT) reinforced phenol formaldehyde (PF) resin intercalated nano-composite of PF–MMT was prepared from phenol, formaldehyde, and pristine MMT. We then introduced this PF–MMT into the production of plywood from Simao Pine veneers. Matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF), wide-angle X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal mechanical analysis (TMA), and bonding strength revealed the related structure, curing, and mechanical properties. The thermoplastic PF with a linear structure entered the MMT layers and then formed the network structure after cured. The wet bonding strength and modulus of elasticity (MOE) of plywood were improved significantly. This preparation is simple and easy, and can be applied in the production of wood industry.

In this study, we synthesized a poly( N -isopropylacrylamide) (PNIPAm) through the polymerization of N -isopropylacrylamide in distilled water with azodiisobutyronitrile as the initiator and a bisadenine-functionalized poly(ethylene oxide) (A-PEO-A) from the reaction of adenine with a difunctionalized toluenesulfonyl-PEO. When blended together in distilled water, PNIPAm and A-PEO-A formed supramolecular aggregates stabilized through complementary multiple hydrogen bonds between the amide groups of PNIPAm and the adenine units of A-PEO-A. Fourier transform infrared spectroscopy, 1 H nuclear magnetic resonance spectroscopy, transmission electron microscopy, dynamic light scattering, and rheometry revealed the thermo-sensitive behavior and viscoelastic properties of the supramolecular assemblies.

In this study, we used 3-aminopropyltrimethoxysilane, hexanedioic acid, 3-mercaptopropyltrimethoxysilane, and thioglycolic acid to functionalize the surface of micro silver flakes through in-situ replacements. Hexanedioic acid had the best effect on the functionalization. When the content of hexanedioic acid was 0.5–1 wt% of micro silver flakes, it could fully replace the long chain fatty acid and form a very thin molecular film on the surface of micro silver flakes. The micro silver flakes functionalized by hexanedioic acid played a significant role in the regards of improving the properties of electrically conductive adhesives, and letting the adhesives have low viscosity, e.g., 28,000 cPs, low bulk resistivity, e.g., 2.4×10 −4 Ω cm, and high shear strength, e.g, 10.4 MPa.

Two bis (benzimidazoyl) monomers were synthesized, and Poly (N-arylenebenzimidazole ketone) s were prepared by N-C coupling reaction that replaced the NH sites from the bis (benzimidazolyl) derivatives with activated difluorides monomers in sulfolane at 210 °C. All the resulting polymers showed easy solubility compared with traditional polybenzimidazoles. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>240 °C), good thermostability and high decomposition temperatures (>460 °C).

In this study, we presented the use of polyurethane, ethylene-vinyl acetate hotmelt, and nano hexagonal boron nitride particles to prepare high surface adhesion polymer fibers via an elertrospinning method. The shear strength, dynamic tensile properties, and surface morphology have been investigated. These polymer fibers were found to have high shear strength, high tensile stress, and high tensile strain, which may have a good potential application in the matrix materials for thermal interface materials. Polymer fibers with and without nano hexagonal boron nitride particles showed the shear strength of 6.52 MPa and 5.44 MPa respectively on being heated up at 150°C for 45 min.

In this study, we prepared exfoliated nanocomposites from polyvinyl acetate (PVAc) and organic montmorillonite (OMMT) through different synthesis processes. OMMT was exfoliated into layers or sheets of nanoparticles. They dispersed in PVAc matrix randomly. The synthesis processes influenced the dispersion and apparent viscosity significantly. PVAc and PVAc–OMMT both were pseudo-plastic Non-Newtonian fluids and had the normal stress effect (or Weissenberg effect) from pole-climbing phenomenon. By analyzing the apparent viscosity using power-law function equation, Newtonian fluid flow equation, and Cross-Williamson model viscous equation, the synthesis processes and OMMT had a combined effect on the rheology of PVAc and PVAc–OMMT. With the change of synthesis processes and the increase of OMMT content in synthesis system, the calculated molecular weight of PVAc–OMMT increased.

In this study, an exfoliated montmorillonite was prepared through click chemistry from a singly azido-functionalized polyhedral oligomeric silsesquioxane derivative and a montmorillonite intercalated with propargyldimethylstearylammonium bromide. This exfoliated montmorillonite was then introduced into a benzoxazine matrix—prepared from paraformaldehyde, aniline, and phenol—to form polymer/exfoliated clay nanocomposites. Thermogravimetric analysis revealed that the pyrolysis kinetics had a close relationship with the structure of montmorillonite, the assembly process, the anchoring effect, the compatibility of the polymer and intercalator, and the char yield. The polymer/exfoliated clay nanocomposites had a same mechanism function, and the kinetic compensation effect equations revealed the pyrolysis essences.

By gel casting with polymethylmethacrylate microbeads (PMMA) as pore-forming agent, porous boron nitride/silicon nitride (BN/Si3N4) composite ceramics were successfully prepared. The obtained ceramic shows bimodal hierarchical structures that composed of spherical-shaped micro pores depending on PMMA content and irregular sub-micro pores formed by the stacking of ceramic particles. Porosity of the porous BN/Si3N4 ceramics can be well controlled from 53.0 to 60.6 % by the PMMA content from 10 to 40 wt%, as well as the mechanical and dielectric properties. Effect of PMMA content on phase composition and the relationship between microstructure and the basic properties of the porous BN/Si3N4 ceramics was discussed in detail. Microstructure analysis reveals that the sub-micro pores acted as channels between micro pores. BN particles have a relatively denser distribution on the wall of spherical-shaped micro pores with a window between micro and sub-micro pores, and resulting in a half-closed micro pore structure, which is meaningful for material design with concentration of BN particles on the wall of pore structure.

In this study, we incorporated micro-silver flakes and nano-hexagonal boron nitride (BN) particles into a matrix resin to prepare electrically conductive adhesives (ECAs). The humid and thermal aging results under a constant relative humidity level of 85% at 85 °C revealed that the aged ECAs containing 3 wt% of nano-hexagonal BN particles had high reliability. The contact resistance was low and the shear strength high. Nano-hexagonal BN particles have a good effect on the reliability of ECAs that can be used to improve the properties of ECAs.

Five different processes were designed based on the polymerization time and water amount to investigate their influence on the properties of exfoliated nanocomposites synthesized by vinyl acetate (VAc) and montmorillonite-octadecyl trimethyl ammonium bromide (MMT-STAB). The violent stirring, low MMT-STAB content, high polymerization temperature, favorable polymerization time and suitable water amount were very important. PVAc-MMT-STAB had high static tensile and good dispersion. PVAc's linear macromolecular chains were formed in MMT-STAB layers that was exfoliated into layers or sheets of nanoparticles and dispersed randomly. They dispersed together to form the structures of “Strawberry,” “Swallow,” “Tactoids,” “Half Core-Shell” and “Similar Core-Shell”.

It is very helpful to guide design production and processing conditions for polymer-based inorganic or organic nano-composites by investigating their rheology. In this study, an intercalated nano-composite of montmorillonite (MMT)-dioctadecyl dimethyl ammonium bromide (DOAB) was added and reacted with vinyl acetate (VAc) to form the exfoliated nano-composite of polyvinyl acetate (PVAc)–MMT–DOAB through five different synthesis processes. The MMT–DOAB was exfoliated into nano-particles of layers or sheets and dispersed randomly in PVAc matrix. The different synthesis processes affected the dispersion and apparent viscosity of PVAc and PVAc–MMT–DOAB. With the polymerization time shortening and the water decreasing, the dispersion got bad and the apparent viscosity increased. PVAc and PVAc–MMT–DOAB were pseudo-plastic non-Newtonian fluids and both possessed the normal stress effect (Weissenberg effect) that is also called the pole-climbing phenomenon. By the help of the apparent viscosity analyzed using the power-law function equation, Newtonian fluid flow equation and Cross-Williamson model viscous equation, the different synthesis processes and MMT–DOAB had a certain effect on the rheology of PVAc and PVAc–MMT–DOAB. With the change of different synthesis processes and the increase of MMT–DOAB content in the synthesis system, the estimated molecular weight of PVAc–MMT–DOAB was also increased accordingly.

High formaldehyde emission and poor water resistance are two main disadvantages of urea formaldehyde (UF) resin. For that reason, a novel polyvinyl acetate (PVAc) type emulsion curing agent was developed in this paper. PVAc type emulsions, including PVAc, the co-polymer of PVAc and N-hydroxymethyl acrylamide (PVAc–NMA), and the ternary co-polymer of PVAc, NMA, and urea (PVAc–NMA–urea), were the main components. Water, aluminum chloride, ammonium dihydrogen phosphate, polypropylene glycol, silicone oil, and urea were the other components. Under heating, aluminum chloride and ammonium dihydrogen phosphate often underwent thermal decomposition and hydrolysis in solution, produce free acid to cure UF resin, so the curing agent could enhance the curing rate, and then shorten the curing time. In this curing agent, ammonium dihydrogen phosphate and urea worked as formaldehyde removers and reacted with free formaldehyde in UF resin, thus the formaldehyde emission exuded from the plywood could be effectively limited and reduced. The bonding strength of plywood was not improved very much, especially the dry bonding strength, but the wet bonding strength was little enhanced for the active hydroxymethyl group contained in PVAc–NMA and PVAc–NMA–urea underwent a self-cross-linking reaction to improve the bonding strength and adhesion force to the bonded substrate. More importantly, the results from the industrial production experiments were shown to be very good.

To study the dynamic mechanical kinetics of exfoliated nanocomposites using dynamic mechanical analysis, polyvinyl acetate (PVAc)–montmorillonite (MMT)–dioctadecyl dimethyl ammonium bromide (DOAB) was synthesized through five different processes. Different synthesis processes and MMT-DOAB had little effect on the structure of PVAc-MMT-DOAB. MMT-DOAB lowered the glass transition temperature of PVAc, hence improving its low temperature resistance greatly. PVAc and PVAc-MMT-DOAB were homogeneous amorphous linear polymers and they appeared cold crystallized, and their glass transition and cold crystallization kinetics were analyzed using Agrawal integral equation.

To study the glass transition and cold crystallization kinetics, the exfoliated nano-composites synthesized by vinyl acetate (VAc) and organic montmorillonite (OMMT) through different processes were investigated by dynamic mechanical analysis. Different synthesis processes and OMMT had significant effect on their dynamic mechanical properties. They brought combined effect on the modulus, loss tangent, and glass transition temperature ( Tg). OMMT could lower PVAc’s Tg, so improved PVAc’s low temperature resistance. PVAc–OMMT was a homogeneous amorphous linear polymer and it appeared the cold crystallization phenomenon. The glass transition and cold crystallization kinetics were first analyzed using the Agrawal integral equation. The kinetic parameters, including the kinetics mechanism function, the linear fit equation, the linearly dependent coefficient, the activation energy, the frequency factor, the mechanism, the reaction order, and the kinetic compensation effect equation, were obtained.

To improve the chemical, physical, mechanical and thermal properties of polyvinyl acetate (PVAc), N-hydroxymethyl acrylamide (NMA) was used to polymerize with vinyl acetate (VAc). During the emulsion polymerization of VAc using polyvinyl alcohol as protective colloid and ammonium persulfate as initiator, PVAc-NMA was prepared under the conventional conditions in laboratory. In the polymers, larger PVAc-NMA particles and other smaller NMA-NMA particles randomly dispersed together. Their dispersion was good. PVAc-NMA was a pseudo-plastic non-Newtonian fluid, also possessed the normal stress effect (or Weissenberg effect), the pole-climbing phenomenon. With the change of different synthesis processes and the increase in NMA content in the synthesis system, the molecular weight of PVAc-NMA increased. NMA could lower the glass transition temperature of PVAc, and then improved PVAc’s low temperature resistance, so PVAc-NMA could be applied in more harsh or much lower temperature conditions. The static tensile of PVAc-NMA was better. PVAc and PVAc-NMA all had the cold crystallization. The pyrolysis of PVAc and PVAc-NMA was similar. It was found to consist of eight phases. NMA had no obvious effect on the pyrolysis temperature but mainly delayed the thermal degradation process.

To improve the chemical, physical, and mechanical properties of polyvinyl acetate (PVAc), an organic montmorillonite (OMMT) was first prepared by montmorillonite (MMT) and octadecyl trimethyl ammonium bromide (STAB), and then it was added to synthesized PVAc under conventional laboratory conditions. The influence of its variable addition on the properties of PVAc—OMMT was investigated mainly by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and static tension, and the rheology was also investigated by the power-law function equation and the Cross–Williamson model viscous equation. The exfoliated nanocomposite of PVAc—OMMT was obtained; linear macromolecular chains of PVAc were formed in the layers of OMMT, and no chemical bonding appeared between OMMT and PVAc, but there were some physical effects. The dispersion of PVAc—OMMT was better than PVAc. OMMT was exfoliated into layers or sheets of nanoparticles and was randomly dispersed in the matrix of PVAc. The particle diameter of OMMT ranged from 50 to 100 nm, whereas PVAc's diameter ranged from 250 to 500 nm; the smaller OMMT particles were adsorbed around the bigger all PVAc particles and formed a “strawberry” structure. PVAc and PVAc—OMMT were both pseudoplastic non-Newtonian fluids; they possessed the normal stress effect (or the Weissenberg effect), that is the pole-climbing phenomenon. The static tension properties of PVAc—OMMT were much better than PVAc, and the addition of OMMT in polymerization was reasonable and not more than 2.0% of VAc. © 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: 130–140, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20244

This research used low molecular surface modifiers, and observed that chemisorptions took place through the formation of a bond between silver surface and an adsorbed molecule, which improved the dispersion of silver flakes in the organic resin. Several different functionalizers, such as thioglycolic acid, silane and di-acid, were used to functionalize the silver surface. Results of shear viscosity, bulk resistivity etc. showed that by using these low molecular organic functionalizers, isotropic conductive adhesives (ICAs) with lower shear viscosity and better electrical conductivity at high silver fillers content were obtained. The adipic acid had the greatest effect on the rheological and electrical property of ICAs, so its weight percentage in silver flakes was also optimized; ICAs displayed the maximum electrical conductivity when there was 0.5 wt% of silver flakes.

Using in-situ emulsion polymerization, the exfoliated nanocomposites were prepared from vinyl acetate (VAc) and organic montmorillonite (OMMT) through five different experimental conditions. The different experimental conditions and OMMT had little effect on the structure of PVAc–OMMT, but significant effect on the dynamic mechanical properties. They produced a combined effect on the modulus, loss tangent and glass transition temperature (T g). OMMT could lower T g of PVAc, and improved PVAc's low temperature resistance. PVAc and PVAc–OMMT all were homogeneous amorphous linear polymers and they all displayed cold crystallization. The different experimental conditions and OMMT had some effects on the thermal degradation. The thermal degradation process was found to consist of eight phases, and those of PVAc and PVAc–OMMT were similar. OMMT had no obvious effect on the thermal degradation temperature, but mainly delayed the thermal degradation process.

Polyvinyl acetate (PVAc) is considered to be an acceptable environmental friendly adhesive, and montmorillonite (MMT) is a cheap and accessible natural nano-mineral. In this work, MMT was first organically activated by octadecyl trimethyl ammonium bromide (STAB). The intercalated nano-composite, MMT–STAB, was then polymerized with VAc. The influence of various additions of MMT–STAB on the rheology of PVAc–MMT–STAB was analysed using the power-law function equation and the Cross–Williamson model viscous equation. The results showed that MMT–STAB was able to improve the rheology of PVAc. The PVAc and PVAc–MMT–STAB all were pseudo-plastic non-Newtonian fluids, with a flow index (i) of 0.93. The apparent viscosity (η), fluid consistency (I), characteristic time of materials (ζ), zero shear viscosity (η 0), weight average molecular weight (M w), number average molecular weight ( M n) and the solid content (O), all increased with increasing additions of MMT–STAB as a result of the polymerization process. All pr...

Polyvinyl acetate (PVAc) is considered to be a type of environmental friendly adhesive, and montmorillonite (MMT) is a cheap and accessible natural nanomineral. MMT was first organically activated by dioctadecyl dimethyl ammonium bromide (DOAB). The intercalated nanocomposite of MMT-DOAB was added during the synthesis of PVAc in conventional laboratory conditions. The PVAc-MMT-DOAB was mainly studied by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, static tension, and the rheology was also investigated by the power-law function equation and the Cross—Williamson model viscous equation. The exfoliated nanocomposite of PVAc-MMT-DOAB could be obtained. Linear macromolecular chains of PVAc were formed in the layers of MMT-DOAB. MMT-DOAB was exfoliated into nanoparticles of layers or sheets, randomly dispersed in the matrix of PVAc. The particle diameter of MMT-DOAB ranged from 25 to 75 nm, they randomly dispersed with PVAc particles. In addition, the smaller MMT-DOAB particles were adsorbed around the bigger PVAc particles; they formed the ‘strawberry’ structure. PVAc and PVAc-MMT-DOAB were pseudo-plastic non-Newtonian fluids and they all possessed the normal stress effect (or Weissenberg effect), that was the pole-climbing phenomenon. The reasonable addition of MMT-DOAB in polymerization was found to be not more than 2.0 wt.% of VAc.

In this study, we used vinyl acetate (VAc), N-hydroxymethyl acrylamide (NMA), and montmorillonite (MMT) to prepare polyvinyl acetate (PVAc), PVAc-NMA, PVAc-MMT, and PVAc-NMA-MMT. Dynamic mechanical and thermogravimetric analysis revealed their glass transition, cold crystallization, and pyrolysis kinetics. PVAc-NMA, PVAc-MMT, and PVAc-NMA-MMT can be applied in harsh or low temperature conditions and surroundings. They are homogeneous amorphous linear polymers and all have cold crystallization phenomena. NMA and MMT did not have any significant effect on pyrolysis temperatures, but delayed the thermal degradation processes. The glass transition, cold crystallization, and pyrolysis kinetics were analyzed using Agrawal integral equation. C � 2013 Wiley Periodicals, Inc. Adv Polym Technol 2014, 33, 21393; View this article online at wileyonlinelibrary.com.

In this study, an exfoliated montmorillonite was introduced into a benzoxazine matrix—prepared from paraformaldehyde, aniline, and phenol—to form polymer/exfoliated clay nanocomposites. Wide-angle X-ray diffraction, differential scanning calorimetry, dynamic mechanical analysis, thermogravimetric analysis, transmission electron microscopy, and contact angle measurements revealed the structures and thermal and mechanical properties of these polybenzoxazine/clay nanocomposites; the montmorillonite was exfoliated into nanoparticles (single sheets or layers) that were dispersed in the polybenzoxazine matrix. The incorporation of the exfoliated montmorillonite improved the polymer’s glass transition and thermal decomposition temperatures, mechanical properties, and surface hydrophobicity.

In this study, an organic montmorillonite from a montmorillonite (MMT) and a dioctadecyl dimethyl ammonium bromide (DOAB) was added to polyvinyl acetate (PVAc) to prepare the exfoliated nanocomposites of PVAc-MMT-DOAB through five different synthesis processes. PVAc-MMT-DOAB was then investigated using X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and static tensile. PVAc linear macromolecular chains were formed in MMT-DOAB layers and exfoliated into single layers and sheets of nanoparticles to form different interesting structures. The static tensile of PVAc-MMT-DOAB was better than PVAc. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21343; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21343

Starch sweet potato varieties Shangshu 19 and Jixu 23 differing in valid storage root number per plant significantly were used to investigate root characteristics, sugar components in root and leaf at early growth phase and their relationship with the formation of storage root per plant at top cover stage. The results showed that, Shangshu 19 with higher valid storage root number regrew quickly with more new roots after seedling transplanting, developed fiberous roots mainly in the whole early growth phase, and formed a stable rate of top biomass/total root system biomass (T/TR) at 15 and 30 days after planting. Jixu 23 achieved the steady number of adventitious root and valid storage root at 15 and 30 days after planting, respectively. Meanwhile, Jixu 23 showed the lower rate of top biomass/storage root biomass (T/SR) at top cover stage (45 days after planting). On the other hand, in point of metabolism of sucrose and hexoses, and the formation of stored polysaccharide polymers, Shangshu 19 had sig- nificantly lower rate of sucrose/hexoses in the whole early growth phase, formed the greater sucrose concentration gradient be- tween leaves and roots, and had 1-kestose and nystose in roots at 15 and 30 days after planting. Its starch content in leaf was sig