Showing papers by "Ming Qiu Zhang published in 2017"

Multiply fully recyclable carbon fibre reinforced heat-resistant covalent thermosetting advanced composites

Abstract: Nondestructive retrieval of expensive carbon fibres (CFs) from CF-reinforced thermosetting advanced composites widely applied in high-tech fields has remained inaccessible as the harsh conditions required to recycle high-performance resin matrices unavoidably damage the structure and properties of CFs. Degradable thermosetting resins with stable covalent structures offer a potential solution to this conflict. Here we design a new synthesis scheme and prepare a recyclable CF-reinforced poly(hexahydrotriazine) resin matrix advanced composite. The multiple recycling experiments and characterization data establish that this composite demonstrates performance comparable to those of its commercial counterparts, and more importantly, it realizes multiple intact recoveries of CFs and near-total recycling of the principal raw materials through gentle depolymerization in certain dilute acid solution. To our best knowledge, this study demonstrates for the first time a feasible and environment-friendly preparation-recycle-regeneration strategy for multiple CF-recycling from CF-reinforced advanced composites.

Fabrication and nanostructure control of super-hierarchical carbon materials from heterogeneous bottlebrushes.

Abstract: Advances in the performances of many modern materials fundamentally depend upon the exploitation of new micro/nanostructures. Therefore, ingenious design of hierarchical structures through the mimicking of natural systems is of increasing importance. Currently, there is an urgent need for creation of multidimensional carbonaceous structures by integrating a customized hierarchical pore architecture and hybrid carbon framework. Here we report the pioneering fabrication of novel super-hierarchical carbons with a unique carbonaceous hybrid nanotube-interconnected porous network structure by utilizing well-defined carbon nanotube@polystyrene bottlebrushes as building blocks. Hypercrosslinking of such heterogeneous core-shell structured building blocks not only allows for constructing amorphous microporous carbon shells on the surface of graphitic carbon nanotube cores, but also leads to formation of covalently interconnected nanoscale networks. Benefiting from such a well-orchestrated structure, these super-hierarchical carbons exhibit good electrochemical performances. Our findings may open up a new avenue for fabrication of unique and unusual functional carbon materials which possess well-orchestrated structural hierarchy and thus generate valuable breakthroughs in many applications including energy, adsorption, separation, catalysis and medicine.

A Facile Approach Toward Scalable Fabrication of Reversible Shape-Memory Polymers with Bonded Elastomer Microphases as Internal Stress Provider.

Abstract: The present communication reports a novel strategy to fabricate reversible shape-memory polymer that operates without the aid of external force on the basis of a two-phase structure design. The proof-of-concept material, crosslinked styrene-butadiene-styrene block copolymer (SBS, dispersed phase)/polycaprolactone-based polyurethane (PU, continuous phase) blend, possesses a closely connected microphase separation structure. That is, SBS phases are chemically bonded to crosslinked PU by means of a single crosslinking agent and two-step crosslinking process for increasing integrity of the system. Miscibility between components in the blend is no longer critical by taking advantage of the reactive blending technique. It is found that a suitable programming leads to compressed SBS, which serves as internal expansion stress provider as a result. The desired two-way shape-memory effect is realized by the joint action of the temperature-induced reversible opposite directional deformabilities of the crystalline phase of PU and compressed SBS, accompanying melting and orientated recrystallization of the former. Owing to the broadness of material selection and manufacturing convenience, the proposed approach opens an avenue toward mass production and application of the smart polymer.

Self-Healing of Polymer in Acidic Water toward Strength Restoration through the Synergistic Effect of Hydrophilic and Hydrophobic Interactions.

Abstract: To improve reliability, durability, and reworkability of bulk polymers utilized in ubiquitous acidic water, the authors develop a novel hyperbranched polymer capable of self-healing and recycling in a low-pH aqueous environment. The hyperbranched polymer has many hydrophilic and hydrophobic terminal groups. When it is damaged in acidic water, the hydrophilic groups are protonated, forming hydrogen bonds, and closing the crack. Meanwhile, hydrophobic interactions of hydrophobic groups are gradually established across the interface because of the intimate contact of the cracked surface, further reinforcing the rebonded portion. The amphiphilic structure proves to meet both the thermodynamic and kinetic requirements for autonomous rehabilitation. As a result, the unfavored water, which used to impede adhesion between hydrophobic polymeric materials, turns into a positive aid to crack healing. The mechanism involved is carefully analyzed and verified in terms of micro- and macroscopic techniques. The proposed...

Flame-retardant effect of a phenethyl-bridged DOPO derivative and layered double hydroxides for epoxy resin

Abstract: Flame-retardant epoxy resin (EP) composites were prepared by the incorporation of a phenethyl-bridged DOPO derivative (DiDOPO) and modified layered double hydroxide (OLDH) In addition, the flame-retardant behaviour, thermal stability, synergism between DiDOPO and OLDH, and mechanical properties of the flame-retardant EP composites were examined The introduction of a specific amount of OLDH in the intumescent flame-retardant EP led to considerable enhancement in flame retardancy, thermal stability, and mechanical properties Furthermore, the effects of DiDOPO and OLDH on the flame-retardant properties of the EP composites were characterised by the limiting oxygen index (LOI) as well as the UL-94 vertical burning and cone calorimeter tests (CCT) The LOI of the EP/DiDOPO5/OLDH5 composites increased from 218% to 315%, and the composites exhibited the V-0 rating in the UL-94 vertical burning test Moreover, the EP/DiDOPO5/OLDH5 composite exhibited the highest tensile strength and a low peak heat release rate and the total heat release values In addition, scanning electron microscopy observation revealed a considerably more continuous, compact char residue for the EP/DiDOPO/OLDH composite Thermogravimetric analysis and CCT revealed that DiDOPO and OLDHs exert gas- and condensed-phase flame-retardant effects Overall, different flame retardant performance is related to the characteristics of each composite; dispersion state in the EP matrix; and structural changes during burning

Bridging Redox Species-Coated Graphene Oxide Sheets to Electrode for Extending Battery Life Using Nanocomposite Electrolyte.

Abstract: Substituting conventional electrolyte for redox electrolyte has provided a new intriguing method for extending battery life. The efficiency of utilizing the contained redox species (RS) in the redox electrolyte can benefit from increasing the specific surface area of battery electrodes from the electrode side of the electrode–electrolyte interface, but is not limited to that. Herein, a new strategy using nanocomposite electrolyte is proposed to enlarge the interface with the aid of nanoinclusions from the electrolyte side. To do this, graphene oxide (GO) sheets are first dispersed in the electrolyte solution of tungstosilicic salt/lithium sulfate/poly(vinyl alcohol) (SiWLi/Li2SO4/PVA), and then the sheets are bridged to electrode, after casting and evaporating the solution on the electrode surface. By applying in situ conductive atomic force microscopy and Raman spectra, it is confirmed that the GO sheets doped with RS of SiWLi/Li2SO4 can be bridged and electrically reduced as an extended electrode–electr...

Synthesis of novel hierarchical porous polymers with a nanowire-interconnected network structure from core-shell polymer nanoobjects

Abstract: Design and fabrication of the micro/nanostructures of the network units is a critical issue for porous nanonetwork structured materials. Significant progress has been attained in construction of the network units with zero-dimensional spherical shapes. However, owing to the limitations of synthetic methods, construction of porous building blocks in one dimension featuring high aspect ratios for porous nanonetwork structured polymer (PNSP) remains largely unexplored. Here we present the successful design and preparation of PNSP with a novel type of one-dimensional network unit, i.e., microporous heterogeneous nanowire. Well-defined core-shell polymer nanoobjects prepared from a gelable block copolymer, poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene are employed as building blocks, and facilely transformed into PNSP via hypercrosslinking of polystyrene shell. The as-prepared PNSP exhibits unique three-dimensional hierarchical nanonetwork morphologies with large surface area. These findings could provide a new avenue for fabrication of unique well-defined PNSP, and thus generate valuable breakthroughs in many applications.

Preparation method for transparent super hydrophobic polymer thin films

Abstract: The invention provides a preparation method for transparent super hydrophobic polymer thin films; the transparent polymer thin films are prepared by tape casting or directional stretching and other molding processes, a special structure of nano mastoids and grooves is formed on the surface of the polymer thin films by a supercritical CO2 foaming method, and super hydrophobicity and low reflection are achieved while the transparency is kept. The method is suitable for various thermoplastic polymer thin films, and all the thermoplastic transparent polymer thin films with various thickness and areas can be made to have super hydrophobic surfaces by the method. By adjusting supercritical CO2 foaming technological conditions including the temperature, the pressure, the soaking time and the pressure relief rate, and with utilization of a covering object to limit the gas diffusion rate of the thin film surface, the nano structure (the nano mastoid size, the groove depth and width and the like) of the thin film surface can be adjusted conveniently, and thus the super hydrophobicity is achieved while the transparency of the polymer thin films is kept.