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A novel polycyclic naphthoxazine resin (NSA‐thiq) is synthesized via N, O‐acetal forming reaction between o‐hydroxyl naphthaldehyde and 1,2,3,4‐tetrahydroisoquinoline. The chemical structure of the monomer is investigated and confirmed by 1H and 13C NMR, Fourier‐transform infrared (FT‐IR) spectroscopy, and high‐resolution mass spectrometry. Besides, the ring‐opening polymerization behavior similar to ordinary benzoxazine resins is observed by differential scanning calorimetry (DSC) and in situ FT‐IR analyses, leading to the formation of the phenolic cross‐linked network. Notably, DSC thermograms indicate that the newly obtained polycyclic naphthoxazine resin exhibits much lower polymerization temperatures compared to many other reported benzoxazine or naphthoxazine resins. Moreover, the corresponding polybenzoxazine (poly(NSA‐thiq)) shows comparable thermal stability in comparison with thermosets derived from monobenzoxazine resins. As a consequence of these unique performances, NSA‐thiq is applied as a property modifier for a commercialized benzoxazine resin (BA‐a). The glass transition temperature of copolymeric thermosets is enhanced without sacrificing too much thermal stability and heat resistance. Here, another series of naphthoxazine thermosetting resin is explored, which can provide more examples for constructing composites based on thermoset polymers. [ABSTRACT FROM AUTHOR]

Aromatic polyimides have attracted wide attentions in fields of aerospace, microelectronics and defense applications due to their outstanding thermal and mechanical performances. However, the rigidity originating from the imide structure attached with an aromatic ring causes difficulties in processing. In this study, we synthesized two ortho-phthalimide functional benzoxazine monomers with additional cross-linkable groups (including both furan and alkynyl). An ortho-phthalimide functional phenol, 2-(2-hydroxyphenyl) isoindole-1,3-dione (oPP), was obtained by reacting o-aminophenol and phthalic anhydride in acetic acid. Two monofunctional ortho-phthalimide containing benzoxazine monomers (oPP-fa and oPP-pa) were then synthesized using the Mannich reaction based on raw materials of oPP, furfurylamine/propargylamine and paraformaldehyde in toluene. The structures of benzoxazine monomers were confirmed by FT-IR and 1H NMR spectroscopies. We also investigated effects of cross-linkable functionalities on curing behaviors as well as their corresponding polymerization mechanisms. The activation energies of oPP-fa and oPP-pa were calculated by Kissinger and Ozawa equations based on DCS measurements with different heating rates. It demonstrates that the exothermic peak temperature of oPP-pa is located at 178.5 °C, which is much lower than that of oPP-fa (223.3 °C). The alkyne group in oPP-pa plays a catalytic effect role in reducing the ring-opening polymerization temperature of the oxazine ring. Moreover, the thermogravimetric analyzer (TGA) was used to evaluate thermal properties of the obtained polybenzoxazine thermosets. Both thermosets exhibited improved thermal stability compared with some other reported monobenzoxazine-derived polybenzoxazines. [ABSTRACT FROM AUTHOR]

Incorporating dopants into the TiO 2 single crystals lattice is a big challenge because single crystal has a high crystallinity and the nucleation and growth of TiO 2 single crystals is readily subjected to the interference of the dose of dopant precursors. Here, we propose an in situ synthetic strategy for the construct of carbon-doped TiO 2 single crystal nanorods using CPS/TiO 2 as the precursors of TiO 2 nanorods and carbon source via a facile hydrothermal route. This technique involves the preparation of cationic polystyrene spheres (CPS), sequential deposition of TiO 2 precursor, hydrothermal reaction, and the pyrolysis of CPS in a N 2 atmosphere at 450 °C. The morphology and structure of as-prepared C-TiO 2 single crystal nanorods were characterized by TEM, SEM, STEM Mapping, XRD, UV–vis spectroscopy, and XPS. All results confirm the carbon doping in the as-prepared TiO 2 single crystal nanorods. As a result of unique microstructure, the resulting TiO 2 exhibits remarkably visible-light photocatalytic efficiency for the degradation of organic pollutants including methylene blue (MB), Rhodamine B (RhB) and p -nitrophenol (PNP). Therefore, the current study provides a new insight for incorporating dopants into the TiO 2 single crystals lattice. [ABSTRACT FROM AUTHOR]

In this article, polyimide (PI) composite films reinforced by graphitic carbon nitride (g-C3N4) have been synthesized using the in situ polymerization process via thermal imidization. Poly (amic acid) (PAA) solutions were prepared from pyromellitic dianhydride (PMDA) and 4,4′-(4,4′-isopropylidenediphenyl-1,1′-diyldioxy) dianiline (BAPP) in N,N-dimethylacetamide (DMAc) solvent. The different amounts of g-C3N4 obtained from the direct pyrolysis of dicyandiamide (DCDA) at 600°C were incorporated into PAA matrix, which formed g-C3N4/PI composite films by thermal imidization. The morphological structures of the synthesized g-C3N4 and g-C3N4/PI composite films were characterized using fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscopy and transmission electron microscopy. With 2 wt% g-C3N4 incorporated, the tensile strength and elongation at break of g-C3N4/PI composites were increased by about 23% and 21%, respectively, due to the strong interaction between the g-C3N4 particles and PI. Thermogravimetric analysis indicated that the incorporation of g-C3N4 improved the thermal stability of the PI at low g-C3N4 content. Besides, the dielectric and optical properties of these composites were also studied in this article. [ABSTRACT FROM AUTHOR]

Novel 1,3-benzoxazine monomers with ortho -imide and benzocyclobutene functionalities, o HPNI-abcb and o PP-abcb, have been successfully synthesized via Mannich condensation using ortho -imide phenols, 4-aminobenzocyclobutene and paraformaldehyde as starting materials. The chemical structures of synthesized monomers have been confirmed by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and elemental analysis. The structural characterization indicates the presence of isomerism in o HPNI-abcb while no such mechanism can be observed in o PP-abcb. The polymerization behaviors of o HPNI-abcb and o PP-abcb have also been systematically studied using differential scanning calorimetry analysis (DSC) and in situ FT-IR. DSC thermograms show three and two separated exothermic peaks for o HPNI-abcb and o PP-abcb, respectively. The difference in exotherms clearly indicates different polymerization mechanisms are involved in the polymerization process of each benzoxazine. Combined with the variations of characteristic bands during curing process in FT-IR spectra, differentiated multiple polymerization mechanisms rather than a single polymerization mechanism as traditional 1,3-benzoxazine resins have been proposed for both benzocyclobutene-containing benzoxazines. Moreover, thermal gravimetric analyzer (TGA) and the microscale combustion calorimetry (MCC) are used to evaluate the thermal stability and flammability of their corresponding thermosets. Notably, the resulting thermoset derived from o HPNI-abcb shows excellent thermal stability with T d5 of 405 °C and T d10 of 448 °C, while the thermoset based on o PP-abcb exhibits YC 800 value greater than 60%. Furthermore, both thermosets also possess outstanding flame retardancy in the absence of any antiflammable additives with heat release rate values of 23.5 and 22.1 J/(gK) for poly(o PP-abcb) and poly(o HPNI-abcb), respectively, evidencing their great potential application in high-performance fields. [Display omitted] • Two novel o -benzoxazines containing benzocyclobutene have been successfully synthesized. • The thermal properties of thermosets can be enhanced by multiple polymerization mechanisms. • The polybenzoxazine based on norbornene-functional benzoxazine shows excellent thermal stability. [ABSTRACT FROM AUTHOR]

Abstract: A new radical initiator, 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (DMDEHPH), has been used to initiate styrene (ST) and methyl methacrylate (MMA) polymerization in the temperature range of 50–80°C and DMDEHPH concentration range of 0.005–0.100mol/L. The effects of initiator concentration, monomer concentration and reaction temperature on the polymerization rate were investigated in details. The increase of these three parameters will all increase the polymerization rate. The orders of polymerization rate to peroxide group concentration and monomer concentration were found to be 0.5 and 1.0, respectively, which validates the correctness of kinetic model derived from the mechanism of polymerization. The activity energy obtained from the polymerization rate constants at various temperatures is 92.0kJ/mol for ST and 81.4kJ/mol for MMA. The initiator efficiency is in the range of 0.55±0.03 for ST and 0.43±0.02 for MMA under the experiment conditions. And the initiator efficiency decreases with the increase of initiator concentration. [Copyright &y& Elsevier]

Micro- and nano-scale carbon materials have been extensively investigated as additives in lubricants owing to their remarkable capability for friction reduction and enhancement of thermal conductivity within lubrication systems. Nevertheless, it is still highly desirable for oil-based lubricants to involve well-dispersed ultrafine carbonaceous particles without complicated chemical modification. Herein, we present a strategy to achieve 3D graphene additive in lubricants based on rapid laser irradiation. Notably, PAO4 containing 3D laser-induced graphene (LIG) additive exhibits excellent tribological properties in comparison with many other unmodified carbonaceous materials, including graphene, graphene oxide, single-wall nanotubes, and carbon black. In addition, the lubrication properties of PAO4 can be significantly improved by manipulating the concentration of the 3D LIG additive. With the addition of only 0.1 wt% 3D LIG-10, PAO4 lubricant system shows a reduction of 22% in coefficient of friction (COF) and a reduction of 95% in terms of wear coefficient compared to the base oil. In this work we provided a new strategy to produce 3D graphene oil additives for excellent tribological and wear performance. [Display omitted] • 3D porous graphene materials used as lubricant additives have been fabricated. • PAO4 with 3D LIG exhibits excellent tribological properties in comparison with common carbon additives. • PAO4 with 0.1 wt% 3D LIG shows reductions of 22% for COF and 95% of wear. [ABSTRACT FROM AUTHOR]

Although TiO2 is widely used as a promising electrode material for supercapacitors, its potential application suffers from a critical limitation due to its poor electrical conductivity and low rate capability. Here, we report a cost-effective hydrothermal strategy to design and construct a novel 'single-crystal-like' C-doped TiO2 electrode material. The as-synthesized electrode material combines the advantages of TiO2, 'single-crystal-like' features and carbon doping, considerably improving the electrical conductivity of TiO2. The electrochemical measurements demonstrate that the C-doped TiO2 material presents an excellent specific capacitance (449.8 F g−1 at 1 A g−1), which approaches six times more than the value (77.3 F g−1 at 1 A g−1) of P25 electrodes, and far beyond the value of many previously reported TiO2 electrodes. Therefore, this work explores a new method to design high performance electrochemical TiO2 electrode materials by incorporating other dopants into the TiO2 lattice. [ABSTRACT FROM AUTHOR]

In this study, silver nanoparticles (NPs) were successfully encapsulated in a carbonaceous shell to form core–shell Ag@C nanospheres using a one-step green hydrothermal method, which involved reduction of AgNO3 and catalyzing the carbonation of aqueous glucose solution. Simultaneously, the Ag core with a diameter of about 130–180 nm and carbon shells with size ranging from 100 to 120 nm were characterized by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The surface of Ag@C nanospheres had abundant oxygen-containing functional groups, which were beneficial to their dispersion in water. The tribological behavior of Ag@C nanospheres as a water-based additive was investigated using a MS-T3000 ball-on-disk tribometer. The water sample with 1.0 wt% Ag@C nanospheres exhibited 80.6% and 40.4% reduction in the friction coefficient and wear scar width, respectively, compared to pure water. The improved tribological performance of Ag@C nanospheres was ascribed to their perfectly spherical structure, which acted as a rolling bearing between the friction counterparts. Moreover, the Ag core provided internal support through a three-dimensional contact between the Ag nucleus and carbon shell. Therefore, the Ag@C nanospheres showed significant prospects for water-based lubricants. [ABSTRACT FROM AUTHOR]

Ongoing research activities are targeted to explore high photocatalytic activity of TiO 2 -based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO 2 @C-doped TiO 2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO 2 , the preparation of the sandwich-like CPS@SiO 2 @CPS particles, and formation of outer TiO 2 . After the one-step removal of CPS templates by calcination at 450 °C, hierarchical SiO 2 @C-doped TiO 2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV–vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO 2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO 2 -based photocatalysts due to doping. [ABSTRACT FROM AUTHOR]

Magnetic FeO@C nanocomposites with well-defined core@shell structure were synthesized via a facile one-step solvothermal process using ferrocene as both iron and carbon resource in the presence of hydrogen peroxide (HO). The as-prepared FeO@C nanocomposites were employed as adsorbent materials for removal of methylene blue (MB) from aqueous solution. Several experimental parameters, including contact time, acidity of the solution, and initial MB concentration were investigated. The result showed that the equilibrium uptake of MB was related to the MB initial concentration as well as acidity of the solution. The adsorption kinetics of MB was dominated by the pseudo-second order reaction model. Significantly, the synthesized FeO@C nanocomposites could be easily isolated from the adsorption system after adsorbing MB and showed prominent reusability. All results indicated that the prepared FeO@C composites had the potential to be used as adsorbents for the removal of dye pollutant from wastewater. [ABSTRACT FROM AUTHOR]

The persistent efforts have been paid to shift the ultraviolet of titania to visible-light-driven photocatalysis. In this work, we explored a facile, cost-effective method to in situ create C-doped hollow TiO 2 spheres. This method involved the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of TiO 2 precursor via template-directed self-assembly, and the removal of CPS template by calcination at 450 °C. The structure and properties of hollow TiO 2 catalysts were characterized by N 2 desorption–adsorption, X-ray diffraction (XRD), UV–vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). Results confirmed the carbon doping in the as-prepared hollow TiO 2 lattice. When C-doped hollow TiO 2 spheres were used as photocatalysts for the degradation of Rhodamine B under visible-light irradiation, the as-synthesized hollow anatase exhibited a superior photocatalytic activity than the commercial P25 and many TiO 2 -based photocatalysts reported in literature, significantly broadening its potential for many practical applications. [ABSTRACT FROM AUTHOR]

Abstract: Using cetyltrimethylammonium bromide (CTAB) as organic treatment agent, phenylmethylsilicone/organic montmorillonite (OMMT) nanocomposites were prepared by in-situ intercalative polymerization. The internal structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). Mechanical properties, high temperature resistance and barrier performance for gas and water were also studied. The results show that molecules of silicone chains insert into the layer of montmorillonite (MMT), and the interlayer distance of MMT is expanded effectively after polymerization of phenylmethylsilicone prepolymer and methyl methacrylate, even forming exfoliated nanocomposites. The silicone/OMMT nanocomposite containing 8wt% OMMT has better high temperature resistance and barrier properties with low thermal weight loss of 25% at 750°C. The nanocomposite, containing 6wt% OMMT, has better mechanical performance with tension strength of 6.264MPa, which is five times more than that of pure silicone. When the nanocomposite contains 4wt% OMMT, the compression strength is 11.503MPa, which is four times bigger than that of pure silicone. [Copyright &y& Elsevier]

Abstract: A novel hypercrosslinked polymeric adsorbent of LM-6 was prepared by post-crosslinking reaction with 2-naphthol. Bromoethane was used as crosslinking reagent to substitute poisonous organic compound of chloromethyl methylether. Selective adsorption on LM-6 in mixture solution which consisting of 2-naphthol and naphthalene shows that the adsorption of 2-naphthol and naphthalene in aqueous solution are mainly pushed by physical interaction. The adsorption of 2-naphthol is also partly pushed by chemical interaction. The adsorptive enthalpy illuminates that there exists hydrogen-bonding between 2-naphthol and LM-6. Owning to hydrogen-bonding, the adsorption capacity of 2-naphthol on LM-6 is markedly higher than that of naphthalene. In aqueous solution, the adsorption process contains two steps: desorption of water first and then adsorption of solute. Dynamic analysis shows that adsorption capacity of 2-naphthol is higher than that of naphthalene. The adsorption rate is mainly affected by the diffusion of liquid membrane, the diffusion inside particulate or coordinated effect. [Copyright &y& Elsevier]

[Display omitted] • The p-n heterojunction Bi 2 O 3 /Ti3+-TiO 2 photocatalyst was reported by a facile method. • The Bi 2 O 3 /Ti3+-TiO 2 enabled the complete removal (100%) of tetracyclines under visible light. • The effect of environmental factors on the photodegradation of tetracyclines was detailed. • The mechanism on photodegradation was analyzed through LC–MS spectrum. The search for a highly active visible-light photocatalyst toward the complete degradation of antibiotic residuals remains a challenging task due to the fast emergence of antibiotic resistance. To address the problem, we explore a novel p-n heterojunction visible-light photocatalyst by coupling a p-type Bi 2 O 3 with an n-type Ti3+ self-doped TiO 2 porous material. The as-synthesized photocatalyst exhibits a narrowed bandgap (~2.89 eV) and enhanced visible-light absorption, leading to the complete degradation (100%) of antibiotics under visible light irradiation (λ > 420 nm) and excellent recyclability (98%) because of the synergistic effect of Ti3+ self-doping and p-n heterojunction. The results effectively work out the challenging task of the incomplete removal of tetracyclines over almost all of the reported visible-light photocatalysts. Additionally, the effects of antibiotics mixture, pH value, inorganic ions, water matrix, and outdoor light on the degradation of tetracyclines were also detailed. Especially, the transformation pathways and degradation mechanism of tetracycline were revealed in depth via trapping experiments and photoelectrochemical characterizations. Therefore, this work provides a new insight in exploring excellent photocatalysts to realize the complete removal of other refractory organic pollutants under visible light. [ABSTRACT FROM AUTHOR]