Showing papers by "Ming Qiu Zhang published in 2012"
TL;DR: In this paper, a novel polyurethane was synthesized, which consisted of isophorone diisocyanate, polyethylene glycol and photo-reversible moiety 5,7-bis(2-hydroxyethoxy)-4-methylcoumarin.
222 citations
TL;DR: Polyaniline (PANI) nanotube arrays were facilely synthesized via electrochemical polymerization in the presence of ZnO nanorod arrays as sacrificial templates, and they were tested as promising flexible electrode materials for supercapacitor applications.
Abstract: Polyaniline (PANI) nanotube arrays were facilely synthesized via electrochemical polymerization in the presence of ZnO nanorod arrays as sacrificial templates, and they were tested as promising flexible electrode materials for supercapacitor applications.
147 citations
TL;DR: In this paper, a solid-state nanocomposite polymer electrolyte incorporating hyperbranched poly(amine-ester) (HBPAE) grafted nano-silica was prepared and investigated.
Abstract: Solid-state nanocomposite polymer electrolytes based on poly(vinyl alcohol)(PVA) incorporating hyperbranched poly(amine-ester) (HBPAE) grafted nano-silica (denoted as SiO2-g-HBPAE) have been prepared and investigated. Through surface pretreatment of nanoparticles, followed by Michael-addition and a self-condensation process, hyperbranched poly(amine-ester) was directly polymerized from the surface of nano-silica. Then the hypergrafted nanoparticles were added to PVA matrix, and blended with lithium perchlorate via mold casting method to fabricate nanocomposite polymer electrolytes. By introducing hypergrafted nanoparticles, ionic conductivity of solid composite is improved significantly at the testing temperature. Hypergrafted nano-silica may act as solid plasticizer, promoting lithium salt dissociation in the matrix as well as improving segmental motion of matrix. In addition, tensile testing shows that such materials are soft and tough even at room temperature. From the dielectric spectra of nanocomposite polymer electrolyte as the function of temperature, it can be deduced that Arrhenius behavior appears depending on the content of hypergrafted nano-silica and concentration of lithium perchlorate. At a loading of 15 wt% hypergrafted nano-silica and 54 wt% lithium perchlorate, promising ionic conductivities of PVA nanocomposite polymer electrolyte are achieved, about 1.51 × 10−4 S cm−1 at 25 °C and 1.36 × 10−3 S cm−1 at 100 °C.
80 citations
TL;DR: In this article, a review of the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications, is presented. And innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.
Abstract: Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clearly indicate that self-healing polymeric materials turn out to be a typical multi-disciplinary area concerning polymer chemistry, organic synthesis, polymer physics, theoretical and experimental mechanics, processing, composites manufacturing, interfacial engineering, etc. The present article briefly reviews the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications. To ensure sufficient coverage, thermoplastics and thermosetting polymers, extrinsic and intrinsic self-healing, autonomic and non-autonomic healing approaches are included. Innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.
62 citations
TL;DR: In this paper, the authors reviewed achievements in the field of theoretical researches on re-establishment of bonding between broken surfaces of self-healing polymers from microscopic and macroscopic point of view.
Abstract: Bioinspired self-healing polymers have attracted more and more interests. Imparting self-healing ability to existing polymers or developing new polymeric materials capable of self-healing is considered to be a solution for improving their long term stability and durability. This article reviews achievements in the field of theoretical researches on re-establishment of bonding between broken surfaces of self-healing polymers from microscopic and macroscopic point of view. Chains interaction, mechanical models related to healing procedures and effect of healing, design of novel self-healing composite systems, and so forth are summarized and analyzed in detail. Both thermoplastics and thermosets are included to offer a comprehensive knowledge framework of the smart function. The scientific challenges are also highlighted, which are related to the production of more advanced self-healing polymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
60 citations
TL;DR: In this article, thermally remendable two-component polymer blends carrying two types of C-ON bonds in the side chains were synthesized and with the aid of small molecule mimetics, intermolecular reactions involved in thermal reversibility of the polymer blends and self-healing capability were analyzed.
Abstract: The C–ON covalent bond with thermally responsive function opens a new avenue to prepare remendable polymers. Carbon-centered radicals and oxygen-centered nitroxide free radicals produced by homolytic cleavage of C–ON bonds at healing temperature synchronously reorganize to form cross-linked networks, offering effective damage repairing characteristics without losing integrity and load bearing ability of the material even above Tg. To gain a deeper understanding of the mechanisms, thermally remendable two-component polymer blends carrying two types of C–ON bonds in the side chains were synthesized. With the aid of small molecule mimetics, intermolecular reactions involved in thermal reversibility of the polymer blends and self-healing capability are analyzed. It was found that crossover reaction between carbon-centered radicals and oxygen-centered nitroxide radicals is necessary, but the possibility of the irreversible combination of carbon-centered radicals should be eliminated. Polymer solid hinders diffusion of carbon-centered radicals so that the unwanted secondary reaction is depressed even though complete recombination of the cleft C–ON bond is also somewhat blocked. Basically, reversibility and multiple self-healing behaviors of the synthesized polymer blends are satisfactory in addition to the expanded healing temperature range. These results are believed to favor materials design and improve crack healing performance based on efficient bond fission and radical recombination.
40 citations
TL;DR: In this article, a facile method for preparing a graphene polyaniline composite without the necessity of using graphene oxide is proposed, where nano-CdS particles act as a "bridge" connecting PANI via the electrostatic force of attraction between the electron clouds of the sulfur and nitrogen atoms and graphene by π-π stacking.
Abstract: A facile method for preparing graphene–polyaniline composite is proposed without the necessity of using graphene oxide. By adding CdS nanoparticles into the in situ polymerization system consisting of graphene and aniline monomers, a graphene–polyaniline composite with a well-bonded interface is yielded. It is found that the nano-CdS particles act as a ‘bridge’, connecting (i) PANI via the electrostatic force of attraction between the electron clouds of the sulfur and nitrogen atoms and (ii) graphene by π–π stacking. Taking advantage of the effective interfacial interactions, a large enhancement (∼400%) of the photoelectronic performance in the composite is observed. The work opens up a path for maintaining the original structure and properties of graphene during graphene–polymer composite manufacturing.
31 citations
TL;DR: In this article, the authors proposed a facile approach to quantify macromolecular migration in micrometer thick polymer films using a polystyrene (PS)/poly(methyl methacrylate) (PMMA) binary film as the model material, depth profile analysis was conducted by confocal Raman microscopy (CRM).
Abstract: The present work proposed a facile approach to quantify macromolecular migration in micrometer thick polymer films. Using a polystyrene (PS)/poly(methyl methacrylate) (PMMA) binary film as the model material, depth profile analysis was conducted by confocal Raman microscopy (CRM). The results showed mutual diffusion of PS and PMMA molecules across the interface of the immiscible polymer pairs when the binary film had been annealed. In addition, both tracer and mutual diffusion coefficients were determined on the basis of the Fickian model, and the factors that influenced the diffusion behavior were discussed. It is believed that the characterization framework established by the authors has theoretical value and practical meaning.
23 citations
TL;DR: Two π-stacked polymers with different steric structures are synthesized and characterized and demonstrate nonvolatile write-once-read-many-times (WORM) memory behavior, and flash memory behavior with an ON/OFF current ratio of approximately 10(5), which may offer a guideline for the design of practical polymer memory devices via tuning steric structure of ρ-stacks polymers.
Abstract: In order to investigate the steric effect of aromatic pendant groups and the electrical bistability in nonconjugated polymers potentially for memory device applications, two π-stacked polymers with different steric structures are synthesized and characterized. They exhibit two conductivity states and can be switched from an initial low-conductivity (OFF) state to a high-conductivity (ON) state. Additionally, they demonstrate nonvolatile write-once-read-many-times (WORM) memory behavior with an ON/OFF current ratio up to 104, and flash memory behavior with an ON/OFF current ratio of approximately 105. Both steady-state and time-resolved fluorescence spectroscopies are used to examine the conformational change of the polymers responding to an applied external electrical voltage. The results provide useful information on different steric effects of pendant groups in polymer chains, resulting in various electrical behaviors. The possibility in realizing an “erasable” behavior through breaking π-stacked structures of pendant groups by a reversal of the electric field was also discussed on the basis of temperature-dependent fluorescence spectroscopy investigation. These results may thus offer a guideline for the design of practical polymer memory devices via tuning steric structure of π-stacked polymers.
20 citations
TL;DR: In this paper, the authors proposed to add 1 wt% nanosilica to oriented polypropylene (PP) to increase the tensile strength of the polyethylene.
Abstract: With the addition of 1 wt% nanosilica, oriented polypropylene (PP) shows ultra-high tensile strength at break (≈ 320 MPa, stronger than unidirectional glass fiber (∼60 wt%)/PP composites and a low-carbon steel) through solid-state drawing strategy. When nano-SiO2 is present in the drawn PP, the aligned macromolecular chains in amorphous regions can be tied by the well distributed nanofillers to share the stress together. Above the critical content of nanoparticles or drawing ratio, the nanoparticles form a percolated network throughout the matrix, facilitating stress transfer in the amorphous phases during tensile test. Additionally, the nanoparticles favor microfibrillation of the polymer matrix mainly constituted by the crystalline phases. As a result, the high strength covalent bonds of macromolecules in both the amorphous and crystalline phases are brought into full play. Although successful application of adding nanofillers to strengthen polymers is widely spread in rubbers and gels, the increase in strength of semi-crystalline polymers by low aspect ratio nano-inclusion is insignificant up to now. The work is believed to open an avenue for reinforcing semi-crystalline polymers by nanoparticles.
19 citations
TL;DR: The outcomes of the present work might help to produce a new family of conjugated organic/inorganic semiconductor nanocomposites with designed optoelectronic performances.
Abstract: In this paper, the effect of the internal micro-magnetic field (IMMF) on the photocurrent property of conjugated polymer/inorganic semiconductor nanocomposites is reported and analyzed. By using the redox reaction, magnetic Fe3O4 nanoparticles were coated on the surface of highly active nanorods of conjugated polyaniline (PANI), forming an internal micro-magnetic electron donor (i.e., Fe3O4@PANI). After subsequent incorporation of CdS nanoparticles (serving as electron acceptors), the power conversion efficiency (PCE) of the system (Fe3O4@PANI-CdS) was found to be as high as 3.563 %, contrasting sharply with the value (1.135 %) of the hybrid without Fe3O4 (PANI-CdS). This obvious enhancement originated from the fact that the IMMF increased the number of singlet polaron pairs through field-dependent intersystem crossing (ISC), giving a positive contribution to the photocurrent generation. Additionally, the dependence of the photocurrent on the remnant magnetization of the Fe3O4@PANI-CdS nanocomposites was investigated. A percolation behavior was observed, which was due to the appearance of interpenetrating networks consisting of donor and acceptor phases, leading to the recombination of charge carriers through trapping. The outcomes of the present work might help to produce a new family of conjugated organic/inorganic semiconductor nanocomposites with designed optoelectronic performances.
TL;DR: In this paper, the authors investigated the effect of branching structure on entanglement and phase separation behavior in semi-dilute ternary polymer solutions, and they found that the branching effect did not monotonously reduce the compatibility of polymer components.
TL;DR: In this article, a wormhole-like mesoporous tungsten carbide/carbon (WC/C) composites can be prepared by combining emulsion processing with triblock copolymer self-assembly strategy, followed by a high-temperature carbothermal reduction.
TL;DR: In this paper, a series of periodic mesoporous organosilicas (PMOs) were prepared by co-condensation of 1,4-bis (triethoxysilyl) benzene (BTEB) and triethoxyvinylsilane (TEVS) using the triblock copolymer Pluronic P123 as a template under acid conditions.
Abstract: A series of vinyl-functionalized periodic mesoporous organosilicas (PMOs) were prepared by co-condensation of 1,4-bis (triethoxysilyl) benzene (BTEB) and triethoxyvinylsilane (TEVS) using the triblock copolymer Pluronic P123 as a template under acid conditions. It is found that the mesophases of resultant PMOs can be controlled via altering the fraction of organosilanes in the synthesis mixture and catalyst HCl concentration. With increasing fraction of TEVS, mesophase of the PMOs materials changed from p6mm to Ia3d, and then becomes a disordered material. For PMOs with 15 molar percentage of TEVS, the increase of HCl concentration can induce a transformation of mesophases from hexagonal p6mm to cubic Ia3d, whereas, a mixture of p6mm/disordered structure forms at lower acid concentration for the PMOs containing 5 % TEVS. The mechanisms of mesophase transformation were discussed based on the adsorption of TEVS into the micelles, influence of acid concentration on the hydrolysis and condensation rate, and the relative reactivities of the organosilane precursors.
TL;DR: In this article, nano-sized SiO2 particles grafted with hyperbranched aromatic polyamide were employed as fillers for fabricating epoxy based composites, which was selected because it...
Abstract: Nano-sized SiO2 particles grafted with hyperbranched aromatic polyamide were employed as fillers for fabricating epoxy based composites. The hyperbranched aromatic polyamide was selected because it...
TL;DR: In this paper, the authors applied the Resonance Light Scattering (RLS) technique to study macromolecular entanglement in highly dilute poly(vinyl methyl ether) (PVME)/poly(ethylene oxide)(PEO) solution during phase transition process.
Abstract: Resonance light scattering (RLS) technique was applied to study macromolecular entanglements in highly dilute poly(vinyl methyl ether) (PVME)/poly(ethylene oxide) (PEO) solution during phase transition process. Temperature dependences of RLS intensities of PVME, PEO and PVME/PEO solutions were recorded. In addition, simulated temperature dependence of RLS intensity of PVME/PEO solution was drawn supposing there was no interaction between PEO and PVME. Comparison between the measured with the simulated results indicated that there were obvious differences in RLS intensities and transition temperatures. The present work proved the existence of entanglements during phase separation in highly dilute solution. Moreover, a model was proposed to describe the entanglement behavior.
TL;DR: By using elastic light scattering (ELS) spectroscopy, dependences of lower critical solution temperature (LCST) of polyvinyl methyl ether (PVME)/poly(ethylene glycol) (PEG) solutions on concentration and molecular weight of PEG were analyzed as discussed by the authors.
Abstract: By using elastic light scattering (ELS) spectroscopy, dependences of lower critical solution temperature (LCST) of poly(vinyl methyl ether) (PVME)/poly(ethylene glycol) (PEG) solutions on concentration (C
PEG) and molecular weight of PEG were analyzed. It was found that the onset temperature of phase separation (T
p) decreased with increasing C
PEG or molecular weight of PEG in the solutions. It indicated that PEG was competitive with PVME in complexing water molecules. The presence of PEG disturbed the hydration layer around PVME, facilitating the aggregation of PVME chains at lower temperature. Moreover, the ELS spectra revealed the aggregation and dissociation of molecular chains in PVME/PEG solutions during one heating and cooling cycle. PVME chains aggregated above the microphase transition temperature. With further increasing temperature, PVME aggregates started to contract, and then kept stable. During cooling, the chain aggregates were not immediately swelled but gradually swelled, and began to dissociate when the solution temperature was further decreased. Finally, the conformation of the molecular chains returned to its original state.