Yinglin Li

Improved hydrophilicity, permeability, antifouling and mechanical performance of PVDF composite ultrafiltration membranes tailored by oxidized low-dimensional carbon nanomaterials

Polyvinylidene fluoride (PVDF)–oxidized carbon nanotubes (OMWCNTs), PVDF–graphene oxide (GO) and PVDF–OMWCNTs–GO composite ultrafiltration membranes were prepared by solution-blending the ternary mixture of PVDF–oxidized low-dimensional carbon nanomaterials–dimethylacetamide in combination with the phase inversion method. The microscope images of the PVDF matrix microstructure showed that the composite membranes exhibited a bigger mean pore size and higher roughness parameters than pristine membranes. The contact angle of the membranes decreased from 78.5° (PVDF) to 66.8° (PVDF–OMWCNTs), 66.4° (PVDF–GO) and 48.5° (PVDF–OMWCNTs–GO). For the PVDF–OMWCNTs, PVDF–GO and PVDF–OMWCNTs–GO composite membranes, there was a 99.33%, 173.03% and 240.03% increase in permeation flux and a 21.71%, 17.23% and 14.29% increase in bovine serum albumin (BSA) rejection, respectively, compared with those of the pristine membranes. The newly developed composite ultrafiltration membranes demonstrate an impressive prospect for the anti-irreversible fouling performance in multi-cycle operations from BSA treatment. Additionally, the addition of OMWCNTs and GO increased the tensile strength of composite membranes from 1.866 MPa to 2.106 MPa and 2.686 MPa, respectively. Conspicuously, the PVDF composite ultrafiltration membranes endowed with oxidized low-dimensional carbon nanomaterials demonstrated fascinating hydrophilicity, permeability, antifouling and mechanical performance and promising application prospects owing to the rich oxygen-containing functional groups, high specific surface and synergistic effect of inorganic additive.

A facile strategy to prepare functionalized graphene via intercalation, grafting and self-exfoliation of graphite oxide

A facile method of successive intercalation, grafting and exfoliation of graphite oxide in monomers by γ-ray irradiation to obtain functionalized graphene nanosheets was reported. The monolayer percentage of functionalized graphene nanosheets was sharply increased and the agglomeration showed a significant decrease.

Nano-structure and property transformations of carbon systems under γ-ray irradiation: a review

Carbon-based materials have been used quite successfully for decades within industry sectors. Especially, the application of them in the field of aerospace has been paid lots of attention. The severe environment such as γ-rays in space, which may give rise to the formation of atomic defects, may deteriorate the performance of carbon-based devices significantly. However, in addition to the well-known cases of destroying the properties of carbon systems, recent experiments show that γ-ray irradiation can also be employed as an attractive tool for the fabrication, modification and manipulation of carbon materials. In this article, we briefly review the recent progress in our understanding of γ-ray irradiation-induced phenomena in some carbon systems with experimental results and theoretical analysis. Particular emphasis is put on the discussion of the effects of γ-rays on nanostructure and morphology of carbon fibers, graphite, carbon nanotubes, graphene and diamond, as well as the methods for tailoring their mechanical, chemical and electronic properties. Finally, we attempt to identify the future directions in which the irradiation-induced modification field is likely to develop.

Modifying graphite oxide nanostructures in various media by high-energy irradiation

The alterations of GO nanostructures after γ-ray irradiation in water, air and styrene with an absorbed dose of 200 kGy are systematically investigated. The interlayer structures of the ultimate products are confirmed to be remarkably different from each other due to the distinct changes of functional groups on single-sheets in various media. After irradiation in water, oxygen groups in graphite oxide are shown to be obviously decreased owing to the generation of reductive radicals by the decomposition of water molecules, which is reflected in the decrease of graphite oxide interlayer spacing. The interlayer distance of graphite oxide irradiated in air is found to be significantly increased, which may be attributed to the increase of the hydroxyl groups and the topological defects. However, the graphite oxide seems to be mainly exfoliated and functionalized by the intercalation of the monomers and the grafting of polystyrene chains when irradiated in styrene. It is expected that γ-ray irradiation in different media should be a promising strategy for manipulating nanostructures and properties of graphite oxide for improving its applicability in fields of composites, catalysts and sensors.

Effects of ion irradiation on carbon nanotubes: a review

Ion irradiation with energetic particles can successfully be used for changing the properties of carbon nanotubes (CNTs) by functionalising, connecting, and creating defect structures in the CNTs. In this paper, we focus on the recent progress in our understanding of ion-irradiation-induced phenomena in CNTs. The production of defects (vacancies and interstitials) and the structural change of CNTs were reviewed. The ion induced modification of the properties was illustrated and the factors such as the substrate, the circumstance of the ion and the temperature which affect the defects and the properties of the ion-irradiated CNTs were also briefly investigated. By summarising the predecessors’ research, we point out the issues which still lack complete investigating and further outline the most promising ways of using beams of energetic particles for CNT-related nano-engineering.

Small angle X-ray scattering study of microvoid evolution and pertinence of microvoid and mechanical properties in γ-irradiated CFs

To explore the mechanism of microvoid evolution and the pertinence of microvoid and mechanical behavior of carbon fibers (CFs) in γ-irradiation, T700 CFs were exposed to γ-rays under epoxy chloropropane (ECP) and argon (Ar) at room temperature. The results from small angle X-ray scattering (SAXS) showed that the average microvoid radius of the CFs decreased gradually from 4.8406 nm for pristine fibers to 3.6868 nm (ECP) and 3.4223 nm (Ar), indicating that γ-irradiation could obviously decrease the microvoid in CFs owing to annealing and rearrangement effects. More significantly, active media would enlarge the surface microvoid of fibers, thus the microvoid of CFs irradiated in ECP was overall larger than that in Ar. The tensile strength of CFs was increased from 5.74 GPa for the pristine fibers to 6.78 GPa (Ar) and 6.18 GPa (ECP) for the irradiated CFs along with a decrease in the microvoid. Therefore, this would provide a key to investigate the evolution of the CF microvoid during γ-irradiation, which was conducive to improving the mechanical properties of γ-irradiated CFs.