Polyamide I1 （PAll） and its nanocomposites with different organoclay loadings were prepared by melt-compounding and subsequent pelletizing. The crystal phase transitions of PAl 1 and its clay nanocomposites were investigated by variable-temperature X-ray diffraction. It was found that the Brill transition of the nanocomposite was 20 K higher than that of the neat PAl 1 for both heating and cooling processes. The PAl 1 d-spacings of the nanocomposites were observed to be smaller than those of the neat PAl 1 for melt crystallization. The constraints imposed by the addition of layered clay, restricting the thermal expansion of the polymer chains, are probably responsible for such a reduction of the d-spacing.
Surface modification of halloysite nanotube（HNT） with in situ grown Fe304 nanoparticles and carbona- ceous layers introduced by a hydrotbermal carbonization process of glucose has been achieved. Structure and mor- phology investigations demonstrate that iron oxide nanoparticles are uniformly anchored on the halloysite and pre- vent the aggregations of halloysite and carbon, forming a protective layer that stabilizes and improves the property of HNT/Fe3OdC nanocomposite. Magnetism characterization proves the superparamagnetic behavior of HNT/Fe304/C hybrid at room temperature, which makes it easily separated from dye solution under an external magnetic field. Ex- ploration of adsorption ability demonstrates that the maximum adsorption capacity of the as-prepared HNT/Fe304/C nanoeomposite for methylene blue（MB） is about twice and 1.5 times those of HNT/Fe304 and HNT according to Langmuir equation, respectively. The adsorption behavior investigations indicate that HNT/Fe304/C hybrid has a he- terogeneous structure and shows a non-ideal monolayer adsorption that fits the Redlich-Peterson isotherm, and the adsorption process follows a pseudo-second-order kinetic model. Therefore, the as-prepared HNT/Fe304/C hybrid is a fast, separatable and superparamagnetic adsorbent with a good adsorption ability, demonstrating great potential in the application of water treatment.
Synergistic effect in network formation of nylon-6 （PA6） nanocomposites containing one dimensional （ID） multi-walled carbon nanotubes （CNTs） and two dimensional （2D） layered double hydroxide （LDH） platelets on improving the mechanical properties has been studied. Mechanical tests show that, with incorporation of 1 wt% LDHs and 0.5 wt% CNTs, the tensile modulus, the yield strength as well as the hardness of the ternary composite are greatly improved by about 230%, 128% and 110% respectively, as compared with neat PA6. This is mainly attributed to the unique, strong interactions between the CNTs and the LDHs as well as the jammed network-like structure thus formed between the nanofillers, as confirmed by the morphological observations. As compared with the binary nanocomposites, a much enhanced solid-like behavior in the terminal region of the rheological curves can clearly be observed for the ternary system, which also indicates the formation of a percolating filler network.
In this study, macroscopic graphene-wrapped melamine foams （MF-G） were fabricated by an MF-templated layer-by-layer （LBL） assembly using graphene oxide as building blocks, followed by solution-processed reduction. By concisely duplicating sponge-like, highly ordered three-dimensional architectures from MF, the resulting MF-G with an interconnected graphene-based scaffold and tunable nanostructure was explored as compressible, robust electrodes for efficient energy storage. A thin layer of pseudocapacitive polypyrrole （PPy） was then attached and uniformly coated on MF-G, resulting in a well-defined core- double-shell configuration of the MF-G-PPy ternary composite sponges. The as-assembled devices exhibited enhancement of supercapacitor performance, with a high specific capacitance of 427 F·g-1 under a compressive strain of 75% and an excellent cycling stability with only 18% degradation after 5,000 charge- discharge cycles. Besides, the MF-G-PPy electrode maintained stable capacitance up to 100 compression-release cycles, with a compressive strain of 75%. These encouraging results thus provide a new route towards the low-cost, easily scalable fabrication of lightweight and deformation-tolerant electrodes.
Recently,graphene has attracted numerous interests from both fundamental and applied fields due to its excellent mechanical,thermal,electrical conductivity and other novel properties.This review gives an overview of recent progress on hybridization modifications of graphene with carbon nanomaterials.Some example applications of graphene-based nanohybrids in polymer composites,optical and conducting materials,high performance electrolyte materials and as well as other functional materials are summarized and discussed.
The reduced graphene oxide（RGO）/γ-A1OOH hybrids with different γ-AlOOH contents were successfully prepared via a facile one-pot hydrothermal method. In these hybrids, RGO acts as a conductive linker for improving electron transport, and γ-AlOOH nanoplatelets help to adsorb the target metal ions on the electrode surface, thus faci- litating the electrochemical behavior of the hybrids. The sensitivity of as-prepared RGOγ-AlOOH hybrids toward Pb（II） was tested by square wave anodic stripping voltammograms（SWASV）and the mass ratio of graphene to γ-AlOOH was optimized to improve the sensing performance of RGOγ-AlOOH hybrids. Owing to the superior ab- sorbability of γ-AlOOH for heavy metal ions and excellent electrical conductivity of graphene, the detection limit of the hybrids for heavy metal ions was found to be as low as 1.5× 10^-11 mol/L with optimized γ-AlOOH content in the hybrids. The experimental conditions, such as pH value, mass of electrode material, and deposition time were also investigated and optimized. The as-prepared RGOγ-AlOOH hybrids demonstrate high electrochemical activity and good sensing performance, which offers an alternative platform for the electrochemical sensors.
The soluble nature of polysulfide species created on the sulfur electrode has severely hampered the electrochemical performance of lithium-sulfur （Li-S） batteries. Trapping and anchoring polysulfides are promising approaches for overcoming this issue. In this work, a mechanically robust, electrically conductive hybrid carbon aerogel （HCA） with aligned and interconnected pores was created and investigated as an interlayer for Li-S batteries. The hierarchical cross-linked networks constructed by graphene sheets and carbon nanotubes can act as an ＂internet＂ to capture the polysulfide, while the micro- and nano-pores inside the aerogel can facilitate quick penetration of the electrolyte and rapid transport of lithium ions. As advantages of the unique structure and excellent accommodation of the volume change of the active materials, a high specific capacity of 1,309 mAh.g-1 at 0.2 C was achieved for the assembled Li-S battery, coupled with good rate performance and long-term cycling stability （78% capacity retention after 600 cycles at 4 C）.
Mingkai LiuZhibin YangHao SunChao LaiXinsheng ZhaoHuisheng PengTianxi Liu
