Rare earth complexes using azobenzene-containing poly(aryl ether)s with different absorption wavelengths as macromolecular ligands: synthesis,characterization, fluorescence properties and fabrication of fluorescent holographic micropatterns

In this paper, two novel azobenzene-containing poly(aryl ether)s with different absorption wavelengths were synthesized via Ullmann coupling and Sonogashira coupling, respectively. The obtained polymers were characterized and evaluated by elemental analysis, IR, ¹H NMR, UV-vis, DSC and TGA. Rare earth complexes were prepared by using the two novel azobenzene-containing poly(aryl ether)s as macromolecular ligands. The obtained rare earth complexes were characterized by elemental analysis, IR and WAXD. The influence of the absorption wavelength of azobenzene chromophores on the fluorescent properties was investigated. The polymer whose absorption wavelength was far from the excitation wavelengths of the rare earth complexes showed a much larger fluorescence intensity. By exposing the films of the rare earth complexes to two interference laser beams, SRGs can be formed on the films and can also be detected by fluorescence microscopy measurement.

Preparation and fluorescence properties of rare earth complexes using azobenzene-containing poly(aryl ether)s with different absorption wavelengths as macromolecular ligands.     

Dissolution of epoxy thermosets via mild alcoholysis: the mechanism and kinetics study

Thermoset dissolution based on degradable bond or exchange reaction has been recently utilized to achieve thermosetting polymer dissolution and recycling. In this paper, an industrial grade epoxy thermoset was utilized as a model system to demonstrate the thermoset dissolution via solvent assisted transesterification (or alcoholysis) with high efficiency under mild conditions. The anhydride–cured epoxy thermoset was depolymerized by selective ester bond cleavage in 1,5,7-triazabicyclo[4,4,0]dec-5-ene (TBD)–alcohol solution below 180 °C at ordinary pressure in less than two hours. The epoxy dissolution proceeded in a surface erosion mode via transesterification that was coupled with catalyst–alcohol diffusion. Based on this observation, a surface layer model containing three layers, namely the gel layer, solid swollen layer and pure polymer layer was used to analyze the thermoset dissolution kinetics. The epoxy dissolution kinetics was derived from the surface layer model, which could be used to predict the dissolution rate during the diffusion-rate-controlled dissolution process well. The results show that alcohols with larger diffusivity and better solubility lead to a higher alcohol/catalyst concentration in the gel layer and promote faster erosion and dissolution of epoxy. This is the first work to show that it is possible to depolymerize industrial epoxy using the principle of dynamic bonds with fast dissolution rate at mild temperature under ordinary pressure.

An industrial grade epoxy thermoset was utilized as a model system to demonstrate the thermoset dissolution via solvent assisted transesterification with high efficiency under mild conditions.     

Assembly of reduced graphene oxides into a three-dimensional porous structure via confinement within robust cellulose oligomer networks

The assembly of nanomaterials into a networked superstructure is a strategy used to construct macroscopic porous materials having the functional properties of nanomaterials. However, because nanomaterials generally prefer densely packed assembled states owing to their high surface energies, the construction of a fine porous structure is still a challenge. In this study, we demonstrate the assembly of reduced graphene oxides (rGOs) into a fine porous structure via confinement within robust cellulose oligomer networks. The confinement of rGOs within cellulose oligomer networks was achieved in one step via the enzymatic synthesis of cellulose oligomers. When the resultant cellulose oligomer gels confining rGOs were reduced by hydrogen iodide, the robust cellulose oligomer networks served as a confinement space for rGOs, preventing excessive aggregation of the rGOs and thus encouraging their assembly into a fine porous structure. Electrochemical measurements revealed that the porous rGO materials could act as electrode materials for supercapacitors. Our strategy based on simple physical confinement will allow for the creation of functional porous materials with excellent nanomorphologies from various nanomaterials.

Reduced graphene oxides were assembled into a fine porous structure via confinement within robust cellulose oligomer networks.     

Poly(arylene ether)s with aromatic azo-coupled cobalt phthalocyanines in the side chain: synthesis,characterization and nonlinear optical and optical limiting properties

A novel poly(arylene ether) with azo-coupled cobalt phthalocyanine in the side chain (PAE-azo-CoPc) was prepared by 1,2-benzodinitrile, anhydrous cobaltous chloride and a novel azobenzene-containing poly(aryl ether) (PAE-azo-DCN) via a nucleophilic substitution polycondensation based on a novel bisfluoro monomer, 4-[(3,4-cyanophenyl)diazenyl]phenyl-2,6-difluorobenzoate. The obtained polymers were characterized and evaluated by FT-IR, ¹H NMR, DSC and TGA. PAE-azo-CoPc exhibited higher glass transition temperature and better thermal stability than PAE-azo-DCN because of the introduction of cobalt phthalocyanine groups. The results of Z-scan measurements demonstrated that PAE-azo-CoPc showed reversible saturable absorption and positive refraction, and PAE-azo-DCN showed saturable absorption and negative refraction. By calculation, PAE-azo-CoPc exhibited larger third-order nonlinear optical susceptibilities than that of PAE-azo-DCN. The results of optical limiting measurements demonstrated that the PAE-azo-CoPc exhibited an excellent optical limiting response.

A novel poly(arylene ether) with azo-coupled cobalt phthalocyanine in the side chain was prepared by 1,2-benzodinitrile, anhydrous cobaltous chloride and a novel azobenzene-containing poly(aryl ether).     

Reversible photo-responsive gel–sol transitions of robust organogels based on an azobenzene-containing main-chain liquid crystalline polymer

Stimuli-responsive supramolecular gels have been widely investigated, but the construction of a liquid crystalline gel with a high mechanical property and reversible photo-response still remains a challenge. This is due to the difficulty of designing gelators with liquid crystal properties and gelation abilities in organic solvents simultaneously. In this study, an azobenzene-containing main-chain polyester (Azo-mLCP) with a pendant amide group was synthesized. The organogel of Azo-mLCP via a hydrogen bond in dioxane possessed reversible thermal- and photo-responsive behaviours. The organogel exhibited a good self-supporting ability when the concentration of the gelator was more than 7.5 wt%. The rapid trans-to-cis isomerization of Azo-mLCP in solution was studied via UV-Vis absorption spectra. In addition, the gel-to-sol transition of the organogel could be triggered efficiently by an incomplete trans-to-cis conversion strategy. This study opens a way for the main-chain liquid crystalline polymers to serve in potential applications in photo-responsive robust actuators, electro-optical devices, and so on.

A robust and photo-responsive organogel has been constructed by introducing an azobenzene-containing main-chain liquid crystalline polymer gelator.     

Effect of concentration of glycidol on the properties of resorcinol-formaldehyde aerogels and carbon aerogels

By using glycidol as a catalyst, high porosity, low-density resorcinol (R) and formaldehyde (F) aerogels and carbon aerogels (CAs) were synthesized via a sol-gel method. The effect of glycidol and water on the color, density, morphology, textual characteristics and adsorption properties of the resultant RF aerogels and CAs were investigated in detail. The results revealed that the properties of RF aerogels and CAs can be controlled by adjusting the amount of glycidol and water. The resultant RF aerogels and CAs were porous materials, the minimum densities of RF aerogels and CAs were 96 and 110 mg cm⁻³ respectively while the maximum specific surface areas of RF aerogels and CAs were 290 and 597 m² g⁻¹. The maximum adsorption capacity of CAs was about 125 mg g⁻¹ on Rhodamine B, which was higher than that of some reported CAs catalyzed by base and acid catalysts. The sol-gel mechanisms of RF aerogels and CAs can be attributed to the opening of the epoxy group of glycidol in the mixture of R and F.

The sol-gel mechanism of glycidol-catalyzed RF aerogels is the opening of the epoxy ring rather than the preservation the of epoxy ring.     

Preparation of environment-friendly solid epoxy resin with high-toughness via one-step banburying

Solid epoxy resin is highly desired in adhesives, electronic materials and coatings due to the attractive characteristics of solvent-free, highly efficient utilization and convenient storage and transportation. However, the challenges remain in fabricating high-toughness solid epoxy resin through a facile and efficient way. Here, a high-performance environment-friendly solid epoxy resin was fabricated by employing maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) as the flexibilizer via one-step banburying method. The results showed that the modified epoxy resin maintained a high glass transition temperature (T_g) and thermal stability, while its impact strength, tensile toughness and flexural toughness were significantly increased compared with the neat epoxy resin. The impact strength, tensile toughness and flexural toughness of R-EM10 are improved 138%, 195% and 149%, respectively. The EVA-g-MAH was introduced in the epoxy matrix as a separate phase to increase toughness via transfer stress and dissipated energy. The attractive properties of this facile fabrication process and the high-toughness, as well as the environment-friendly performance make this solid epoxy highly promising for large-scale industrial application.

High-toughness and environment-friendly solvent free solid epoxy resin through a low-cost, facile and large-scale fabrication process.     

Synthesis of hierarchical MgO based on a cotton template and its adsorption properties for efficient treatment of oilfield wastewater

A biomorphic MgO nanomaterial was fabricated via a facile and low-cost immersion method using cotton as the template. The obtained materials were characterized via X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N₂ adsorption–desorption analysis. The as-prepared MgO retained the structure of cotton, with a porous hierarchical structure and a high specific surface area, which endowed it with great potential due to its excellent adsorption properties for the adsorption of additives in oil field wastewater. It also exhibited the maximum adsorption capacity of 391.36 mg g⁻¹ for sulfonated lignite. The adsorption process of sulfonated lignite on biomorphic MgO was systematically investigated and was found to obey the pseudo-second-order rate equation and the Langmuir adsorption model. The negative values of Gibbs free energy change (ΔG) showed that the adsorption process was feasible and spontaneous. The endothermic process was depicted with a positive value for ΔH.

A biomorphic MgO nanomaterial was fabricated via a facile and low-cost immersion method using cotton as the template.     

Synergistic effect of functionalized graphene oxide and carbon nanotube hybrids on mechanical properties of epoxy composites

Epoxy resin was grafted to graphene oxide (GO) via esterification reaction and 3D structure hybrids were prepared by combining 1D carbon nanotube (CNT) and 2D functionalized GO through π-stacking interaction. Epoxy composites filled with 3D structure hybrids were fabricated. The results show that functionalized GO effectively improves the dispersibility of CNTs in epoxy matrix due to good compatibility. Excellent mechanical properties were achieved by epoxy composites filled with 3D structure hybrids. The fracture surface analysis indicated improved interfacial interaction between 3D structure hybrids and epoxy matrix, which may due to the covalent bonding formed between the epoxy molecular chain grafted on EGO and the hardener agent during the curing process. In the 3D structure filler network, the mechanisms of crack deflection/bifurcation induced by functionalized GO make the crack path tortuous, which causes the cracks to encounter more CNTs and then promote the mechanisms of CNT fracture and crack bridging, resulting in more energy dissipation. This is the key mechanism for its excellent reinforcing and toughening effects.

The 3D structure hybrids obtained by combining CNT and epoxy functionalized GO exhibit an obvious synergistic effect on the improvement of mechanical properties of epoxy composites.     

Structure of benzene from mass-correlated rotational Raman spectroscopy

We present high resolution rotational Raman spectra and derived geometry parameters for benzene. Rotational Raman spectra with sub-5 MHz resolution were obtained via high-resolution mass-correlated rotational alignment spectroscopy. Isotopologue spectra for C₆H₆, ¹³C–C₅H₆, C₆D₆, and ¹³C–C₅D₆ were distinguished through their correlated mass information. Spectra for ¹³C₆H₆ were obtained with lower resolution. Equilibrium and effective bond lengths were estimated from measured inertial moments, based on explicit assumptions and approximations. We discuss the origin of significant bias in previously published geometry parameters and the possibility to derive H,D isotope-specific bond lengths from purely experimental data.

We present high resolution rotational Raman spectra and derived geometry parameters for benzene isotopologues. Rotational Raman spectra with sub-5 MHz resolution were obtained via high-resolution mass-correlated rotational alignment spectroscopy.     

N2-selective alkylation of NH-1,2,3-triazoles with vinyl ethers via gold catalysis

A new method was developed to synthesize N²-alkyl-substituted 1,2,3-triazoles via gold catalyzed alkylation of vinyl ethers with mono- and unsubstituted NH-1,2,3-triazoles and benzotriazole. A hydrogen bond between the oxygen atom of the vinyl ethers, activated via the gold catalyst, and the NH-1,2,3-triazoles was supposed to be generated, which selectively gave the N²-alkylation products.

A new method was developed to synthesize N²-alkyl-substituted 1,2,3-triazoles via gold catalyzed alkylation of vinyl ethers with mono- and unsubstituted NH-1,2,3-triazoles and benzotriazole.     

Formation mechanism and characterization of porous biomass carbon for excellent performance lithium-ion batteries

Porous biomass carbon derived from corn stalks was prepared via carbonization and activation of CaCl₂. Combined with its microstructure, the formation mechanism and electrochemical properties were analyzed. The addition of CaCl₂ was the key factor to form the porous structure, and the proportion of CaCl₂ had a significant impact on the pores distribution and electrochemical properties. The resulting sample had a specific surface area of 370.6 m² g⁻¹ and an average pore size of 9.65 nm. The sample was circulated at 0.2C for 100 cycles, the specific discharge capacity was 783 mA h g⁻¹. After 60 cycles at different rates, when the current was restored to 0.2C again, the discharge specific capacity quickly recovered. This showed that the sample had excellent rate performance and cycle stability for lithium-ion batteries.

Porous biomass carbon derived from corn stalks was prepared via carbonization and activation of CaCl₂.     

Synthesis of diversely substituted bis-pyrrolizidino/ thiopyrrolizidino oxindolo/acenaphthyleno curcuminoids via sequential azomethine ylide cycloaddition

Curcumin has been transformed to several diversely substituted bis-pyrrolizidino/thiopyrrolizidino oxindolo/acenaphthyleno curcuminoids via a sequential azomethine ylide cycloaddition reaction using isatins/acenaphthoquinone and proline/thioproline as the reagents. The products were separated via extensive chromatography and characterized by 1D/2D NMR and HRMS analysis.

Curcumin has been transformed to several diversely substituted bis-pyrrolizidino/thiopyrrolizidino oxindolo/acenaphthyleno curcuminoids via a sequential azomethine ylide cycloaddition reaction.     

Functionalized epoxy with adjustable fluorescence and UV-shielding enabled by reactive addition of 9-anthracenemethoxyl glycidyl ether

Functionalized epoxies show unique advantages in some special applications. Herein, a fluorescent and UV-shielding dual-functional epoxy resin, epoxy-EAn, is prepared via synthesizing and incorporating a reactive additive, 9-anthracenemethoxyl glycidyl ether (EAn), into the resin system. The results show that EAn performs an outstanding migration resistance. The addition of a small amount of EAn (0.1%) enables epoxy-EAn to emit bright blue-violet fluorescence under UV light, making epoxy-EAn a feasible fluorescent adhesive for reconstruction and repair. The fluorescence emission intensity is adjustable by the treatment with UV light and heat. Correspondingly, the epoxy-EAn can serve as an information storage material to realize information input and decryption. In addition, epoxy-EAn also possesses the ability to shield UV radiation, and transmittance in the near ultraviolet and middle ultraviolet region (200–400 nm) can decrease to zero when the EAn concentration is 0.8%. Meanwhile, epoxy-EAn also shows excellent mechanical properties similar to that of the pure epoxy. This work paves a facile way to fabricate a multi-functional epoxy suitable for various occasions.

A fluorescent and UV-shielding epoxy resin is prepared via synthesizing and incorporating a reactive additive, 9-anthracenemethoxyl glycidyl ether, into the resin system.     

Quantification of azide groups on a material surface and a biomolecule using a clickable and cleavable fluorescent compound

Here, we propose a novel method for quantifying azide groups on a solid surface and a protein using a clickable and cleavable fluorescent compound. The clickable and cleavable fluorescent compound conjugates with the azide groups on the material surface and the fluorophore is then liberated into the solvent via a cleavage reaction, which can be simply quantified with a conventional fluorometer.

We propose a novel method for quantifying azide groups on a solid surface and a protein.     

Facile multifunctional IOL surface modification via poly(PEGMA-co-GMA) grafting for posterior capsular opacification inhibition

Posterior capsule opacification (PCO) is a significant complication of intraocular lens (IOL) implantation in cataract surgery, in which the adhesion and proliferation of lens epithelial cells (LECs) on the implanted IOL surface play an important role. The surface modification of IOL to prevent LEC adhesion and proliferation is a practical way to reduce the incidence of PCO. In this study, a multifunctional binary copolymer of poly(ethylene glycol) methacrylate (PEGMA) and glycidyl methacrylate (GMA) was synthesized (poly(PEGMA-co-GMA), PPG) and chemically grafted onto the aminolyzed IOL surface, utilizing the coupling reaction of epoxy and amino groups. Doxorubicin (DOX) was subsequently immobilized on the surface coating via the reaction of epoxy and amino groups as well. Taking advantages of the hydrophilicity of the PEG segments in the copolymer coating and the anti-proliferative effects of the DOX, a multifunctional surface coating was easily established by the synthesized copolymer PPG. Such anti-proliferative drug immobilized hydrophilic coating modification may effectively reduce the cell adhesion and proliferation and thus it is hypothesized to have great potential in PCO inhibition. The synthesis of PPG was confirmed by proton nuclear magnetic resonance spectroscopy (¹H-NMR) and Fourier transform infrared spectroscopy (FTIR). The surface coating immobilization was demonstrated by X-ray photoelectron spectroscopy (XPS). The in vitro drug release profiles and the cell behaviors were also investigated to validate the multifunctional coating inhibition effect on cellular adhesion and antiproliferation. Finally, the in vivo ocular implantation was carried out on rabbit eyes to evaluate the effect of the coating modified IOL on the inhibition of postoperative PCO. It followed that such multifunctional coating modification can effectively inhibit the adhesion and proliferation of LECs and significantly reduce the incidence of PCO. All these results reveal that such PPG copolymer modification provides a facile yet effective way to inhibit PCO formation after IOL implantation.

Drug eluting and hydrophilic intraocular lens surface coating was facilely fabricated via poly(PEGMA-co-GMA) grafting. Such a multifunctional coating reduced posterior capsular opacification incidence after implantation effectively.     

Preparation of an (inorganic/organic) hybrid hydrogel from a peptide oligomer and a tubular aluminosilicate nanofiber

‘Imogolite’, a tubular inorganic nanotube surface, was modified with a peptide oligomer to prepare a hybrid hydrogel. The formation of the gels was confirmed by conducting a vial inversion test and rheological measurements. The surface modification of imogolite with the peptide oligomer was verified by performing thermogravimetric analysis and circular dichroism measurements. Furthermore, the formation of the network-like morphology of the prepared hydrogel was confirmed by scanning force microscopy.

‘Imogolite’, a tubular inorganic nanotube surface, was modified with a peptide oligomer to prepare a hybrid hydrogel.     

Synthesis and characterization of tung oil-based UV curable for three-dimensional printing resins

Using tung oil as the raw material, a new bio-based prepolymer was successfully synthesized by reacting with acrylic-modified rosin (β-acryloyl nutrient ethyl) ester (ARA)/acrylic-2-hydroxyethyl ester (HEA) followed by the use of the above composite material as the matrix and then reacting with the active diluent (2-HEMA, TPGDA) and the photoinitiator TPO and Irgacure1173 to successfully synthesize a new type of bio-based prepolymer-acrylate-epoxy tung oil polypolymer (AETP). The tung oil monomer before and after the epoxy formation was compared by proton NMR spectroscopy, and the chemical structure of AETP was analyzed by Fourier transform spectroscopy. Tung oil has an acid value of 1.5 mg KOH per g, an epoxy value of 5.38%, an iodine value of 11.28 g/100 g, and a refractive index of n²⁵ = 1.475. Composite-based 3D printing resins (like AETP) were cured using digital light treatment, while some samples were also post-treated via ultraviolet (UV) light treatment. The AETP-based 3D printing resin has excellent thermal and mechanical properties, and the viscosity of its system is 313 mPa s; exposure time 4.5 s; the tensile strength, flexural strength and flexural modulus were 62 MPA, 63.84 MPa and 916.708 MPa, respectively; Shore hardness was 80 HD and shrinkage was 4.00%. The good performance of the AETP-based 3D printing resin is attributed to the rigidity of their tightly crosslinked structure. This study pioneered a method for producing photoactive acrylates (e.g., tung oil-based acrylate oligomer resins) from renewable, low-cost biomass for light-curing 3D printing.

Using tung oil as the raw material, a new bio-based prepolymer was synthesized by reacting with ARA/HEA as the matrix and then reacting with the diluent and photoinitiator to synthesize a new bio-based prepolymer-acrylate-epoxy tung oil polypolymer.     

Opening the internal structure for transport of ions: improvement of the structural and chemical properties of single-walled carbon nanohorns for supercapacitor electrodes

We investigated the electrochemical performance of single-walled carbon nanohorns (SWCNHs) for use as supercapacitor electrodes. For the first time, we used acid-treatment for oxidation of SWCNHs and hole creation in their structure. A detailed study was performed on the correlation between the oxidation of SWCNHs via acid treatment and variable acid treatment times, the structural properties of the oxidized carbon nanostructures, and the specific capacitance of the SWCNH electrodes. We showed that simple functionalization of carbon nanostructures under controlled conditions leads to an almost 3-fold increase in their specific capacitance (from 65 to 180 F g⁻¹ in 0.1 M H₂SO₄). This phenomenon indicates higher accessibility of the surface area of the electrodes by electrolyte ions as a result of gradual opening of the SWCNH internal channels.

The correlation between the oxidation of single-walled carbon nanohorns (SWCNHs) via acid treatment and the electrochemical properties of the SWCNH electrodes is presented.