Jiheng Ding

Study on the curing reaction kinetics of a novel epoxy system

The anhydride curing agent of 3,6-enodro-1,2,3,6-tetrahydrophthalic anhydride (OBPA) and the reactive epoxy diluent of furfuryl glycidyl ether (FGE) were prepared and characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR). The curing reaction kinetics process of an EP/OBPA/FGE epoxy system was studied by non-isothermal DSC methods. The parameters of the kinetics were calculated using the Kissinger model, Crnae model, Ozawa model and β–T (temperature–heating speed) extrapolation, respectively. In addition, the effect of FGE on the thermomechanical properties (glass transition temperature) and mechanical properties (flexural strength and the tensile strength) in the EP/OBPA/FGE were studied, indicating that when the content of FGE was 10 wt% the epoxy system reaches the best mechanical properties.

Lignin nanoparticles: synthesis, characterization and corrosion protection performance

The conversion of micro lignin to lignin nanoparticles (LNP) and their application in engineering and technology are potential steps towards global sustainability because lignin is obtained from industrial and agricultural waste and can be used in green chemistry. In the present study, we report the high-yield synthesis of lignin nanoparticles in different media, i.e., castor oil (CO), ethylene glycol (EG) and water (W) and evaluate their effect on the size and morphology of the LNP. The syntheses of LNP cover 9 out of 12 of the green chemistry principles; the synthesis was carried out via acid precipitation in a polyol medium, which acts as a stabilizing agent. From the results of the TEM, DLS, and SEM studies, it was observed that ≈15–20 nm LNP were successfully formed and spherical morphologies were observed when EG and CO were used as solvents. Furthermore, the anticorrosive behaviour of these nanoparticles was evaluated; the LNP acted as anticorrosive nanofillers for the protection of carbon steel (CS) in stringent corrosive conditions and was dispersed in an epoxy matrix to formulate epoxy nanocomposite coatings. Physicomechanical and electrochemical impedance spectroscopy (EIS) studies suggest that LNP-dispersed epoxy coatings potentially protect the underlying materials and show better protection as compared to the bare epoxy coatings.

A water-based green approach to large-scale production of aqueous compatible graphene nanoplatelets

The unique properties of graphene are highly desired for printing electronics, coatings, energy storage, separation membranes, biomedicine, and composites. However, the high efficiency exfoliation of graphene into single- or few-layered nanoplates remains a grand challenge and becomes the bottleneck in essential studies and applications of graphene. Here, we report a scalable and green method to exfoliate graphene nanoplatelets (GNPs) from nature graphite in pure water without using any chemicals or surfactants. The essence of this strategy lies in the facile liquid exfoliation route with the assistance of vapor pretreatment for the preparation of edge hydroxylated graphene. The produced graphene consisted primarily of fewer than ten atomic layers. Such the water soluble graphene can be stored in the form of dispersion (~0.55 g L−1) or filter cake for more than 6 months without the risk of re-stacking. This method paves the way for the environmentally friendly and cost-effective production of graphene-based materials.

The efficient exfoliation and dispersion of hBN nanoplatelets: advanced application to waterborne anticorrosion coatings

Although numerous papers have reported that graphene is a superior anticorrosion nanofiller, it has also been demonstrated that graphene cannot be used as a long-term anticorrosion barrier due to its essential high conductivity. Herein, an anticorrosive nanofiller (BNQDs@hBN) combining the nanomaterial boron nitride quantum dots (BNQDs) with insulating hexagonal boron nitride (hBN) is put forward. The homogeneous dispersion of BNQDs@hBN in an epoxy matrix was achieved with the assistance of BNQDs, and was based on strong π–π interactions between h-BN and BNQDs, as confirmed via UV-vis spectra. Embedding a small percentage of BNQDs@hBN in a waterborne epoxy (WEP) coating effectively improves the barrier properties of the coating by inhibiting the penetration of corrosive ions. Polarization tests revealed that the protection efficiency and corrosion rate of an epoxy coating with 0.5 wt% BNQDs@hBN were 99.99% and 6.482 × 10−5 mm year−1, respectively. Electrochemical impedance spectroscopy (EIS) results demonstrated that the 0.5 wt% BNQDs@hBN coating system showed a higher impedance modulus (>107) than that of a blank specimen after immersion for 60 days in 3.5 wt% NaCl(aq).

Efficient exfoliation of layered materials by waste liquor

Based on their unique material properties, two-dimensional (2D) nanomaterials such as graphene, molybdenum disulfide (MoS2), and boron nitride (BN) have been attracting increased research interest. The potential of 2D materials, in the form of nanoplatelets that are used as new materials, will be important to both nanomaterials and advanced materials. Water is usually considered to be the ideal dispersed medium, and the essential hydrophobicity and limitations to mass production of 2D nanoplatelets have become quite serious obstacles to their usage in various fields. In this paper, pulping black liquor was used as dispersant, with high concentration of lignin to get single- and few-layered nanoplatelets. The whole process required only the high-shear mixing of 2D layered materials and pulping waste liquor. This method was not only simple and efficient but also environmentally friendly and resource-recycling. Moreover, the fabricated single- or few-layered nanoplatelets possessed good solubility in aqueous solution due to their edge functionalization, and could be well dispersed in water at concentrations (10 mg ml-1 for graphene, 6.3 mg ml-1 for MoS2, and 6.0 mg ml-1 for BN) which were much higher than that of other methods. The dispersions of graphene, MoS2, and BN nanosheets were highly stable over several months, which allowed us to easily prepare graphene, MoS2, and BN films through simple vacuum filtration or spraying. These results indicated that pulping black liquor can be used as a material or reagent, and the mass production of 2D material is possible in a simple and fast method.