Ionic polymer membrane cast from the mixture of poly(sodium 4-styrenesulfonate-co-acrylic acid) (PSA) and polyvinyl alcohol (PVA) was used as an electromechanical actuator. Surface modified multiwalled carbon nanotubes (MWNTs) were used as an efficient element to enhance the gripping of this actuator. In particular, a thin layer of PSA with a thickness of 12 nm is uniformly grafted on the surfaces of MWNTs. The water-soluble PSA-g-MWNTs can be homogeneously dispersed in the PSA/PVA membrane with a loading ratio of up to 20 wt %. Such a uniform dispersion generated many unique properties in this composite membrane, including enhanced toughness, relatively constant ionic-exchange capacity, and prominent structure integrity after water uptake. We argue that all these novel material properties are due to a removal of the interface mismatch between the MWNTs and the polymer membrane. As a result, a much-enhanced gripping is resulted from electrical stimuli, an indication of a promoted electromechanical coupling. When the loading of PSA-g-MWNTs reaches more than 10 wt %, the small oscillation in the mechanical output of the actuator vanishes.

Although various types of nanoparticle have been ubiquitously employed as additives to promote the practical performances of composite polymer electrolytes (CPEs) in lithium-ion batteries, the influence of the type of chemical bond between the core and canopy of the modified nanoparticle on the properties of CPEs has rarely been investigated. Herein, two types of nanoparticle additive, namely, ionic bond modified nanoparticles (IBNs) and covalent bond modified nanoparticles (CBNs), were prepared conveniently based on nanosilica with different particle sizes in order to optimize the overall performance of the electrolyte. Furthermore, the CPEs were fabricated by doping IBNs or CBNs as well as lithium salts within a poly(ethylene oxide) matrix and their electrochemical properties were investigated. The dramatic enhancement of the ionic conductivity of the CPEs resulted from the addition of fillers into the system, and the improvement became more significant when the fillers were IBNs that used the smaller silica nanoparticle as the core segment, due to the increased chain mobility, as estimated by the smaller Tg value. Moreover, a broad electrochemical stability window was obtained in the presence of IBNs, and the lithium-ion transference number of the system containing lithium bis(trifluoromethanesulfonimide), which has large anions in the structure, was almost two times higher than the CPEs using lithium perchlorate as the lithium source. Therefore, the synergistic effects of the filler structures and the electrolyte compositions are the key factors to improve the electrochemical performances of CPEs.

•Superacid PWA coated PVDF nanofibers was prepared by a PDA-assisted coating method.•Artifically constructed three-dimensional proton conductive channels were formed.•Chitosan as a filling polymer can anchor PWA and increase the proton conductivity.•Providing a new way to design PEMs by using of superacid coated electrospun fibers.Electrospun fiber-based composite polymer electrolyte membranes (PEMs) with artifically constructed long-range proton conductive channels have been drawn considerable attention due to their promising applications in fuel cells. Herein, high level of superacidic phosphotungstic acid (PWA) coated poly(vinylidene fluoride) (PVDF/PWA) electrospun mat as a new three-dimensional proton conducting network was prepared using a polydopamine-assisted coating method. Polydopamine can homogeneously adhere PWA on the PVDF nanofibers' surface. This new mat was then used to fabricate PEMs after filled with polycation chitosan. With the introduction of the PVDF/PWA network, the obtained chitosan filled composite membrane showed significantly improved proton conductivity, which was about one order of magnitude higher than that of the chitosan filled pure PVDF membrane. Moreover, the chitosan can not only effectively inhibit the leaching out of PWA through the strong static interaction between chitosan and PWA, but also act as an ionomer matrix to further increase the proton transport. The direct methanol fuel cell of the PVDF/PWA composite membrane exhibits a peak power density of 85.0 mW cm−2, whereas it is only 47.5 mW cm−2 for the membrane without PWA coating. Consequently, this study provides a new strategy to design high-performance PEMs by utilization of solid superacid coated electrospun nanofibers.Download high-res image (272KB)Download full-size image

•The HOR kinetic is controlled by Had adsorption/desorption and transfer impacts from H2 and H+.•Two Had species as HOPD and HUPD play active roles in HOR kinetics.•The HOR kinetic for Fe-based catalyst is attributed to Fe-Had reversibility and PANI/Fe NPs interface change.•First Fe-based catalyst was carried out for anode application in a fuel cell test, even under the C3H8 fuel.Taking the commercial Pt/C catalyst as a baseline, we disclosed Fe-based catalyst prepared by controlled self-assembly can be used to catalyze hydrogen oxidation reaction (HOR) in the proton exchange membrane fuel cells (PEMFCs). Our electrochemical results clarified that the HOR kinetics is H2 → 2Had → 2H+,which are determined by intermediate Had species and transfer impacts from H2 and H+. Specifically, the Fe-based catalyst can accelerate Had adsorption/desorption in low potential due to the Fe-Had reversibility of NPs, and the strengthened mass transfer as well as recoverable active sites of PANI/Fe NPs (polyaniline/Fe NPs) interface in high potential, thus contributing intermittent HOR current in the HOR region. As HOR catalyst, our prototype fuel cell using Fe-based catalyst was demonstrated high EOCP, mass power density and stability in 110 hrs, tolerance for C3H8 fuel, promising in replacing Pt-based catalysts in future.

A facile method to construct scroll-like nanohybrids combining one dimensional ceramic silicon carbide (SiC) nanowires with 2D graphene oxide (GO) nanosheets is presented. The SiC/GO nanohybrids with an oxygen-containing GO outer surface, which are easily and stably dispersed in water and various organic solvents, can be used as a new type of nanofiller for the preparation of easily dispersed poly(propylene carbonate) (PPC)-based nanocomposites using a simple physical blending procedure. The scroll-like structure of the SiC/GO nanohybrids enhances adhesion and the compatibility of SiC with PPC, while preventing the GO sheets from aggregating face-to-face in the PPC. The PPC-based nanocomposites, incorporated with SiC/GO nanohybrids, show synergistic effects with superior thermal, mechanical, shape memory and barrier properties compared to those made as individual (i.e. SiC or GO enhanced) PPC nanocomposites. An optimal performance PPC–SiC/GO nanocomposite that showed improvements in both the glass transition temperature (Tg) and the thermal degradation temperature (Td) was obtained with 0.1 wt% SiC/GO.

It is a constant pursuit to form highly-diffractive and low-voltage-driven holographic polymer dispersed liquid crystals (HPDLCs) for meeting the requirements of practical applications. Nevertheless, the high-voltage-driven characteristic is usually given while improving the diffraction efficiency of HPDLCs, and it remains a challenge to form HPDLCs with concurrent features of high diffraction and low driving voltage via a simple method. In this work, we synthesize a non-room-temperature LC, 4-butyloxy-4′-cyanobiphenyl (4OCB), and mix it with a room-temperature nematic LC mixture named P0616A. These new LC mixtures are then homogeneously mixed with monomers and a photoinitibitor composed of 3,3′-carbonylbis(7-diethylaminocoumarin) (KCD) and N-phenylglycine (NPG), followed by patterning via laser interference, generating well-structured HPDLCs. The introduction of 4OCB into the standard formulation is found to be able to optimize the morphology and electro-optical properties of the resulting HPDLC transmission gratings. By doping 5 wt% of 4OCB into the HPDLCs, a high diffraction efficiency of 92 ± 3% is obtained; meanwhile, the threshold and saturated voltages significantly decrease by 80.8% (i.e., from 12.0 ± 0.8 to 2.3 ± 0.9 V μm−1) and 73.2% (i.e., from 19.0 ± 0.6 to 5.1 ± 0.7 V μm−1), respectively, in comparison with the pristine. The enhanced performance is believed to be ascribed to the formed larger LC droplets (70 ± 20 nm) and lower interface anchoring strength (0.7 μN m−1) of the polymer network on LCs.

High diffraction efficiency and low driving voltage are typically considered to be prerequisites for the practical applications of holographic polymer dispersed liquid crystals (HPDLCs), which are especially critical for their use in the state-of-the-art low-threshold mirrorless tunable lasers. Nevertheless, high driving voltages are usually resulted for HPDLCs upon increasing the holographic diffraction efficiency via optimizing the monomer/LC formulations. Herein, we present that doping nanoparticles into HPDLCs with controlled distribution is a facile and efficient approach to circumvent the aformentioned issues. Zinc sulfide (ZnS) nanoparticle doped HPDLCs with high diffraction efficiency (94.0 ± 2.1%), and a low threshold driving voltage of 2.5 V µm−1 that is decreased from 11.6 V µm−1 for the pristine form, are achieved by doping 8 wt% ZnS nanoparticles into the HPDLCs based on an acrylamide monomer, N,N-dimethylacrylamide, that contributes significantly to the high diffraction efficiency up to 98.2 ± 1.4%.

Holographic photopolymer composites have garnered a great deal of interest in recent decades, not only because of their advantageous light sensitivity but also due to their attractive capabilities of realizing high capacity three-dimensional (3D) data storage that is long-term stable within two-dimensional (2D) thin films. For achieving high performance holographic photopolymer composites, it is of critical importance to implement precisely spatiotemporal control over the photopolymerization kinetics and gelation during holographic recording. Though a monochromatic blue light photoinitibitor has been demonstrated to be useful for improving the holographic performance, it is impractical to be employed for constructing holograms under green light due to the severe restriction of the First Law of Photochemistry, while holography under green light is highly desirable considering the relatively low cost of laser source and high tolerance to ambient vibration for image reconstruction. Herein, we disclose the concurrent photoinitiation and inhibition functions of the rose bengal (RB)/N-phenylglycine (NPG) system upon green light illumination, which result in significant enhancement of the diffraction efficiency of holographic polymer-dispersed liquid crystal (HPDLC) gratings from zero up to 87.6 ± 1.3%, with an augmentation of the RB concentration from 0.06 × 10–3 to 9.41 × 10–3 mol L–1. Interestingly, no detectable variation of the ϕ1/2kp/kt1/2, which reflects the initiation efficiency and kinetic constants, is given when increasing the RB concentration. The radical inhibition by RBH• is believed to account for the greatly improved phase separation and enhanced diffraction efficiency, through shortening the weight-average polymer chain length and subsequently delaying the photopolymerization gelation. The reconstructed colored 3D images that are easily identifiable to the naked eye under white light demonstrate great potential to be applied for advanced anticounterfeiting.Keywords: anticounterfeiting; green light; holography; inhibition; photopolymerization; rose bengal;

Organic molecular and polymeric stabilizers are useful for preparing individually dispersed graphene sheets, thus offering new possibilities for the production of nanomaterials. Although exfoliated graphene flakes with good dispersibility can be produced, their use in polymer composites remains limited due to their low stability and mechanical strength. In this work, stable high concentration aqueous dispersions (>10 mg mL−1) of reduced graphene oxide (RGO) sheets were prepared by exfoliation/in situ reduction of graphene oxide (GO) in the presence of cellulose nanocrystals (CNC). The sandwich-like structure formed with the hydrophilic outer surface of CNC forms CNC decorated RGO (CNC–RGO) which is easily dispersed in water with a high thermal stability (>320 °C) comparable to pristine CNC and other common stabilizers. Polyethylene oxide (PEO) based nanocomposites, using fully exfoliated CNC–RGO hybrids, were prepared with a simple procedure. The PEO/CNC–RGO composite films show superior mechanical properties compared to PEO composite films enhanced by other small molecules, polymer dispersants, stabilized RGO or pristine CNC. Not only are the elastic modulus and tensile strength of the composites significantly improved, but their thermal stability is also retained. The hydrothermal dehydration of GO to RGO, using biodegradable and renewable materials such as CNC, offers a “green approach” to large-scale preparation of highly biocompatible and easily dispersed RGO for a range of applications.

Using the versatility of silica chemistry, we describe herein a simple and controllable approach to synthesise two-dimensional (2D) silica-based nanomaterials: the diversity and utility of the resulting structures offer excellent platforms for many potential applications.

•Reviews applications of advanced carbon materials/LiFePO4 cathode.•Discusses preparation strategies of LiFePO4 composites cathode.•Analyzes influence factors of electrochemical performances.In the past two decades, LiFePO4 has undoubtly become a competitive candidate for the cathode material of the next-generation LIBs due to its abundant resources, low toxicity and excellent thermal stability, etc. However, the poor electronic conductivity as well as low lithium ion diffusion rate are the two major drawbacks for the commercial applications of LiFePO4 especially in the power energy field. The introduction of highly graphitized advanced carbon materials, which also possess high electronic conductivity, superior specific surface area and excellent structural stability, into LiFePO4 offers a better way to resolve the issue of limited rate performance caused by the two obstacles when compared with traditional carbon materials. In this review, we focus on advanced carbon materials such as one-dimensional (1D) carbon (carbon nanotubes and carbon fibers), two-dimensional (2D) carbon (graphene, graphene oxide and reduced graphene oxide) and three-dimensional (3D) carbon (carbon nanotubes array and 3D graphene skeleton), modified LiFePO4 for high power lithium ion batteries. The preparation strategies, structure, and electrochemical performance of advanced carbon/LiFePO4 composite are summarized and discussed in detail. The problems encountered in its application and the future development of this composite are also discussed.This article reviews the advanced carbon materials/olivine LiFePO4 composite cathodes for lithium ion batteries.

A facile and effective approach by incorporating silica nanoparticles (SNPs) to fabricate high performance epoxy-based electronic packaging materials which are both thermally conductive and electrically insulating was presented. Because of the strong interaction between SNPs and silver nanowires (AgNWs), uniformly dispersed SNPs-modified epoxy was employed to promote the dispersion of AgNWs in epoxy matrix. Further, the enhanced modulus of epoxy matrix by the incorporation of SNPs effectively alleviates the modulus mismatch between stiff AgNWs and epoxy matrix. Compared with epoxy/AgNWs composites without SNPs, the resulting hybrid materials, that is, epoxy/SNP/AgNWs, showed distinct improvements in thermal conductivity without degrading their mechanical properties. Also, the SNPs were absorbed onto the surface of AgNWs forming an electrical insulation layer to disrupt the electron flows between adjacent AgNWs, hence retaining the electrical insulation of epoxy matrix. Finally, this new fabrication method is easily scalable owing to its simple procedure and use of commercial well-dispersed SNPs-modified epoxies.

•BAPC has good miscibility with plasticizer DAP.•The phase transition diagram of BAPC/DAP blends with DCP as initiator during heating has been constructed.Bisphenol-A polycarbonate (BAPC) is an important engineering plastic with superior optical and mechanical properties, but it is difficult to be processed due to the high melt viscosity. In this work, the blends of BAPC and reactive plasticizer of diallyl phthalate (DAP) were studied before and after polymerization of DAP using dicumyl peroxide (DCP) as thermal initiator. The morphology evolution and phase transitions of the blends during heating were investigated by polarized optical microscopy equipped with hot stage and differential scanning calorimetry. With raising temperature, the apparent phase transitions, i.e., thermally induced partial phase separation with upper critical solution temperature (UCST) behavior, BAPC cold crystallization, DAP polymerization and BAPC crystal melting, occurred in sequence. Compared to pure BAPC, the BAPC/poly(DAP) blends with 10–15 wt.% of poly(DAP) had good performances, including similar glass transition temperature, tensile strength and ∼80% of optical transmittance in the wavelength range of 600–800 nm, as well as an increase of 64–68% for moduli and 100–135% for melt flow index, respectively. These good performances were attributed to the bicontinuous structure of the blends. This study provides a facile strategy to realize the easy processing for intractable polymers and to maintain, even to enhance the high performances of the original polymers.Download full-size image

Poly(ethylene oxide) (PEO) based materials are widely considered as promising candidates of polymer hosts in solid-state electrolytes for high energy density secondary lithium batteries. They have several specific advantages such as high safety, easy fabrication, low cost, high energy density, good electrochemical stability, and excellent compatibility with lithium salts. However, the typical linear PEO does not meet the production requirement because of its insufficient ionic conductivity due to the high crystallinity of the ethylene oxide (EO) chains, which can restrain the ionic transition due to the stiff structure especially at low temperature. Scientists have explored different approaches to reduce the crystallinity and hence to improve the ionic conductivity of PEO-based electrolytes, including blending, modifying and making PEO derivatives. This review is focused on surveying the recent developments and issues concerning PEO-based electrolytes for lithium-ion batteries.

A new structural design and tailored morphology of polymer-functionalized graphene (polymer-FG) are employed to optimize composite polymer electrolytes (CPEs). The ionic transfer conditions including Li salt dissociation, amorphous content and segmental mobility are significantly improved by incorporating polymer-FG, especially that having a polymeric ionic liquid (PIL) and a polymer brush structure [PIL(TFSI)-FGbrush]. Electrical shorts are eliminated due to the presence of the functionalized polymer on reduced graphene oxide (RGO) and a minimal amount of polymer-FG in the PEO/Li+ polymer electrolytes (PEs). Polymer-FG with PIL brushes increases significantly the Li ion conductivity of PEO/Li+ PE by >2 orders of magnitude and ∼20-fold at 30 °C and 60 °C with high Li salt loading (O/Li = 8/1), respectively. Furthermore, significant improvements in mechanical properties are observed where only 0.6 wt% addition of the PIL(TFSI)-FGbrush led to more than 300% increase in the tensile strength of the PEO/Li+ at an O/Li ratio of 16/1. Li-ion battery performance was evaluated with the CPE containing 0.6 wt% of PIL(TFSI)-FGbrush, resulting in superior capacity and cycle performance compared to those of the PEO/Li+ PE. Thus, we believe, embedding minimal amounts of structurally and morphologically optimized polymer-FG nano-fillers can lead to the development of a new class of SPEs with high ionic conductivity for high performance all-solid-state Li-ion batteries.

Holographic polymer dispersed liquid crystals (H-PDLCs) pertain to one type of intriguing switchable electro-optical device, and there is a constant need to quantitatively understand the photopolymerization kinetics and gelation process during the formation of H-PDLCs for the purpose of improving the diffraction efficiency and driving voltage. Herein, we quantitatively investigate the effect of the photoinitibitor composed of 3,3′-carbonylbis(7-diethylaminocoumarin) (KCD) and N-phenylglycine (NPG), with initiation and inhibition functions simultaneously generated under monochromatic illumination, on the formation of H-PDLCs. The outcomes reveal that an augmentation of KCD loading from 0.3 × 10−3 to 1.4 × 10−3 mol L−1 dramatically promotes the photopolymerization rate and monomer conversion. Reversely, a further increase in KCD content drastically depresses photopolymerization. The numerical deduction shows that the kinetics complies with the classical photopolymerization kinetics characteristics in the full range of the KCD content. Counterintuitively, the gelation time almost keeps constant when the KCD content is less than 1.8 × 10−3 mol L−1, and then is able to grow by more than 4 times when the KCD loading further increases. Ketyl radical inhibition, which subsequently results in shortened weight-average chain lengths and increased gel point conversions, is believed to account for the kinetics and exceptional gelation behaviors. H-PDLCs with a scaffolding morphology are formed, and with an augmentation of the KCD content, the segregation degree and diffraction efficiency significantly improve from zero to 64% and 78 ± 11%, respectively, and then level off, allowing for the facile fabrication of glass-free colored 3D images; while the critical driving voltage gradually decreases from 8.9 ± 1.0 to 4.6 ± 0.7 V μm−1.

In the last two decades, metal-catalyzed controlled radical polymerization (CRP), or atom transfer radical polymerization (ATRP) has become a ubiquitous tool for the facile synthesis of a wide range of materials with specific macromolecular architectures. The complex plays an important role in ATRP, and for this purpose researchers put a great deal of effort on studying the effect of various complexes on polymerization. However, one of the disadvantages of a copper complex, the most extensively studied catalyst system in ATRP, is the contamination of polymers resulting from a high concentration of stable catalyst. Efficiently and economically removing the catalyst from the resultant polymers will provide a wide variety of new functional polymers for specialty applications, especially for large-scale industrial manufacture. Iron-based catalysts have attracted particular attention because of their low toxicity, low cost, abundance, and environmental friendliness, and thus many iron catalysts have been designed for ATRP. This article reviews the preparation of polymers using iron-catalyzed atom transfer radical polymerization, and is organized according to: (a) mechanistic considerations; (b) iron complexes and ligand types.

An effective chemical strategy for the synthesis of polymer–ionic liquid (IL) electrolytes with ion-conducting channels, physically modulated by variously dimensioned IL-functionalized carbon materials (IL-FCMs) including carbon black (CB), multi-walled carbon nanotubes (MWCNT) and reduced graphene oxide sheets (RGO) is reported, enabling a fundamental understanding of the relationship between carbon structures and ion transport behavior. The risk of electrical shorts is eliminated by the presence of IL groups on the surfaces of CMs and only minimal amounts of the IL-FCMs (⩽1.0 wt.%) in the polymer/IL composite electrolytes (e.g., polymer matrix filled with 1.0 wt.% IL-FCMs has a conductivity of ∼10−7 S cm−1 at 100 °C). Increase in ion transport within the reorganized ion channels of the composite polymer electrolytes (CPEs) is confirmed by the enhanced ionic conductivity and low activation energy for through-plane and in-plane ionic conduction at different temperature (40–160 °C). Maximum improvement in the ionic conductivity (150–300% at 100 °C) can be achieved by optimizing the carbon structure and the loading ratio, which leads to highly ionic conductive polymer/IL composite electrolytes for practical applications.

A series of amide group-containing polar solvents, formamide (Fo), N-methylformamide (MFo), N,N-dimethylformamide (DMF), acetamide (Ac), N-methylacetamide (MAc), N,N-dimethylacetamide (DMAc), urea, tetramethyl urea (TMU), 2-pyrrolidone (2-Py), N-methyl-2-pyrrolidone (NMP) and 5-methyl-2-pyrrolidone (MPy), were used as both solvents and ligands for iron(II)-catalyzed atom transfer radical polymerizations (ATRPs) of methyl methacrylate (MMA), with ethyl 2-bromo-2-phenylacetate (EBPA) as the initiator. Most of the polymerizations were well-controlled in character, and the structures of the polar solvents greatly affected the catalytic activity. In addition, the living features of the systems remained in the presence of limited amounts of polar solvents. Some of the polar solvents (MFo, TMU and 2-Py) were also employed for iron(III)-catalyzed activators generated by electron transfer (AGET) ATRPs of MMA, and the results were as good as those of the ATRPs.

We synthesize zinc sulfide (ZnS) nanoparticles with a diameter of ∼5 nm and formulate novel photopolymer/ZnS nanocomposites for holographic recording. By taking advantage of the photoinitibitor, composed of 3,3′-carbonylbis(7-diethylaminocoumarin) (KCD) and N-phenylglycine (NPG), with a capability of spatiotemporally tailoring the grating formation process, we successfully achieve high performance holographic photopolymer/ZnS nanocomposites with as high as 93.6% of diffraction efficiency (η), 26.6 × 10–3 of refractive index modulation (n1), 8.4 per 200 μm of dynamic range, and 9.8 cm/mJ of photosensitivity. In addition, for an aim of roughly describing the grating formation process, we establish a novel exponential correlation between the ZnS nanoparticles segregation degree (SD) and the ratio of photopolymerization gelation time (tgel) to holographic mixture viscosity (v). Finally, we reconstruct and display 3D images that are clearly identifiable to the naked eye through a master technique, opening a versatile class of potential applications in high capacity data storage, stereoadvertisements, and anticounterfeiting.

Poly(acrylic acid)/azobenzene microcapsules were obtained through distillation precipitation polymerization and the selective removal of silica templates by hydrofluoric acid etching. The uniform, robust, and monodisperse microcapsules, confirmed by transmission electron microscopy and scanning electron microscopy, had reversible photoisomerization under ultraviolet (UV) and visible light. Under UV irradiation, azobenzene cross-linking sites in the main chain transformed from the trans to cis isomer, which induced the shrinkage of microcapsules. These photomechanical effects of azobenzene moieties were applied to the encapsulation and release of model molecules. After loading with rhodamine B (RhB), the release behaviors were completely distinct. Under steady UV irradiation, the shrinkage adjusted the permeability of the capsule, providing a novel way to encapsulate RhB molecules. Under alternate UV/visible light irradiation, a maximal release amount was reached due to the continual movement of shell networks by cyclic trans–cis photoisomerization. Also, microcapsules had absolute pH responsiveness. The diffusion rate and the final release percentage of RhB both increased with pH. The release behaviors under different irradiation modes and pH values were in excellent agreement with the Baker–Lonsdale model, indicating a diffusion-controlled release behavior. Important applications are expected in the development of photocontrolled encapsulation and release systems as well as in pH-sensitive materials and membranes.

Ionic liquid plasticized cellulose (IPC) materials were prepared with microcrystalline cellulose (MCC) and 25–70 wt% 1-butyl-3-methylimidazolium chloride (BmimCl) by direct thermal processing. Their chemical, morphological and crystalline structures were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction, and their glass transition behaviors and mechanical properties were discussed. The results show there is no chemical reaction between cellulose and the ionic liquid. BmimCl only acts as a plasticizer to improve the thermal processability of MCC, the IPC materials show only one glass transition terrace and can be processed repeatedly. Based on the free volume transition and the percolation of continuous hydrogen bonding networks, the effects of free volume and H-bonding interactions on the glass transition have been differentiated. Furthermore, the phase diagram with four regions has been plotted for IPC materials, which is useful to optimize the thermal processing and modulate the properties of cellulose materials.

Controlling the kinetics and gelation of photopolymerization is a significant challenge in the fabrication of complex three-dimensional (3D) objects as is critical in numerous imaging, lithography, and additive manufacturing techniques. We propose a novel, visible light sensitive “photoinitibitor” which simultaneously generates two distinct radicals, each with their own unique purpose–one radical each for initiation and inhibition. The Janus-faced functions of this photoinitibitor delay gelation and dramatically amplify the gelation time difference between the constructive and destructive interference regions of the exposed holographic pattern. This approach enhances the photopolymerization induced phase separation of liquid crystal/acrylate resins and the formation of fine holographic polymer dispersed liquid crystal (HPDLC) gratings. Moreover, we construct colored 3D holographic images that are visually recognizable to the naked eye under white light.

The sulfonated polyphenylsulfone (SPPSU) membranes with different degrees of sulfonation (DS) were prepared for fabricating low-cost and high-performance ionic polymer–metal composite (IPMC) actuators. The properties of SPPSU ion exchange membranes and the electromechanical performance of resulting SPPSU actuators can be manipulated by controlling their DS. As the DS of SPPSU membranes increases, their ion exchange capacity (IEC), water uptake and ion conductivity increase accordingly, whereas the hydrated mechanical properties (strength and modulus) decrease. The SPPSU membrane with the highest DS (SPPSU4) shows much higher IEC and water uptake, and slightly lower ion conductivity than those of the traditional Nafion membrane. Among the prepared IPMC actuators, the SPPSU4 actuator performs the best in the bending deformation under the electric stimulus. The maximum bending strain (MBS) of the SPPSU4 actuator is comparable to that of the Nafion actuator coupled with several times faster bending response at 3 V DC voltage. Compared with the Nafion system, the SPPSU4 actuator increases approximately twice at MBS under a sinusoidal voltage of 3 V at 1 Hz. This greatly enhanced actuation performance indicates that the SPPSU is a candidate to substitute Nafion in the field of IPMC actuators.

•We report a new conductive agent to increase the electrochemical property of LiFePO4.•PEG layer improves the dispersion of MWCNTs and facilitates Li+ diffusion in the cathode.•Highly dispersed MWCNTs increase the thermal conductivity of the cathode.Poly(ethylene glycol) (PEG) grafted multi-walled carbon nanotubes (MWCNTs-g-PEG or MP) were synthesized and used to modify LiFePO4 as cathodes for lithium-ion batteries (LIBs). The effects of different molecular weights of PEG grafted on MWCNTs and different mass fractions of MP on the properties of LiFePO4/MP composite cathodes were evaluated by their morphology, charge–discharge tests, electrochemical impedance spectroscopy, electrical and thermal conductivities. Their electrochemical behaviors at ambient temperature and low temperature, high rate capability and cycling performance were observed in the presence of the MP additives. The lithium ions diffusion in the LiFePO4/MP composite electrodes was almost 2 orders of magnitude higher than that in the LiFePO4/acetylene black (AB) electrode when the conductive additive content was 5 wt.%. Thermal studies of LiFePO4/MP were also examined by the heat-pole method, which showed higher thermal conductivity of the cathode in cases of MP being incorporated into LiFePO4 particles than LiFePO4 cathodes with AB or MWCNTs additives. These results suggest that MP is a promising conductive additive to increase the electrochemical performances, thermal transport and safety of LiFePO4 cathodes for LIBs.

Crosslinking is an efficient and simple approach for enhancing the thermal and mechanical properties of polymers. Numerous studies have reported such enhancements by the incorporation of benzoxazine (a cross-linker) in the polymer's structures. The great majority of these studies have focused on the effect of the benzoxazine content on the polymer matrix. As far as we know, there has been no discussion related to the effects arising from the position of benzoxazine incorporation. In order to investigate any such effects, we synthesized new benzoxazine monomers (SBz and MBz), containing bis-propargyl functional groups and new main chain and side chain benzoxazine functionalized polytriazole polymers, with the above benzoxazine moieties in the repeat unit, using click chemistry. The resulting thermal and mechanical properties of Cured-PTA-SBz-10 were better than those of Cured-PTA-MBz-10, and the Cured-PTA-SBz-4 and Cured-PTA-SBz-6 were close or even better than those of Cured-PTA-MBz-10. To better understand any thermal curing effects related to the positions of benzoxazine moieties in the polymer chain, we performed dynamic differential scanning calorimetric measurements by Kissinger and Ozawa methods. Significant enhancement of the thermal and mechanical properties comparing neat PTA with Cured-PTA-SBz-10 were noted: e.g. (i) a ∼110 °C improvement of Tg; (ii) a ∼205% improvement in storage modulus, a ∼232% improvement of tensile strength, and a ∼262% improvement in Young's modulus. Therefore, when designing the polymer, by giving consideration to the position of the cross-linker, the resulting thermal and mechanical properties can be enhanced to the extent that an equivalent polymer can be formed with a reduced amount of cross-linker leading to cost reduction.

Silver nanowires (AgNWs), as one-dimensional nanostructured materials, possess high aspect ratio and intrinsically high thermal conductivity. However, AgNWs are difficult to disperse homogeneously in epoxy resin, and their high electrical conductivity also limits their applications for electronic packaging. Herein, silica-coated silver nanowires (AgNWs@SiO2) were synthesized by a flexible sol–gel method and then incorporated into epoxy. The less stiff silica intermediate nanolayer on AgNWs not only alleviated the mismatch between AgNWs and epoxy, but also enhanced their interfacial interaction. Hence, the thermal conductivity of an epoxy/AgNWs@SiO2 composite with 4 vol.% filler loading was increased to 1.03 W/mK from 0.19 W/mK of neat epoxy compared to 0.57 W/mK of an epoxy/AgNWs composite with identical nanowire loading. Simultaneously, the insulating silica nanolayer effectively avoided formation of an electrically conductive network of AgNWs in epoxy, leading to high electrical insulation of the composite. AgNWs@SiO2 nanowires with core–shell structure also improved the dielectric properties of epoxy. In addition, these composites possessed a viscosity suitable for the underfill process in electronic packaging.

Liquid-crystalline (LC) physical gels with a high modulus and low driving voltage were prepared through the self-assembly of sorbitol derivatives as gelators in a nematic liquid crystal, 4-pentyl-4′-cyanobiphenyl (5CB). The structural difference among the used gelators, i.e. 1,3:2,4-di-O-benzylidene-D-sorbitol (DBS), 1,3:2,4-di-O-p-methylbenzylidene-D-sorbitol (MDBS) and 1,3:2,4-di-O-m,p-dimethylbenzylidene-D-sorbitol (DMDBS), is only the number of methyl groups on their phenyl rings. The phase transition temperature, mechanical and electro-optical properties of three LC gels were systematically investigated. Compared with DBS, MDBS and DMDBS with methyl groups on phenyl rings have higher gelation ability in 5CB. The three LC gels exhibit good self-supporting ability with storage moduli higher than 104 Pa when the gelator content is increased to 1.5 wt%. At 3.0 wt% and a gelator content less than 1.0 wt%, both moduli of MDBS and DMDBS gels are obviously higher than that of DBS gel due to the enhanced reinforcement of the more rigid, thicker nano-fibrils and the formed nano-fibrillar network texture in MDBS and DMDBS gels. Also, the driving voltages of LC gels decrease in the order of DBS, MDBS and DMDBS gels with increase of LC domain size and nano-fibril diameter. For DMDBS gel with 3.0 wt% gelators, the threshold voltage and saturation voltage are only 0.5 and 3.5 V μm−1, showing its potential application in self-supporting light-scattering electro-optical displays.

Silica-coated multi-walled carbon nanotubes (MWCNT@SiO2) were synthesized by a sol–gel method and then incorporated into an epoxy matrix. The less stiff silica intermediate shell on the MWCNTs not only alleviates the modulus mismatch between the stiff MWCNTs and the soft epoxy, but also improves the interaction between them. The thermal conductivities of the epoxy/MWCNT@SiO2 composites increase by 51% and 67% at low filler loadings of 0.5 wt.% and 1 wt.%, respectively. At the same time, the silica shell retains the high electrical resistivity of these composites.Graphical abstractResearch highlights► Silica shell alleviates the modulus mismatch between CNTs and polymer. ► Modulus matching improves the thermal conductivity of the composites. ► Silica shell provides the composite with electrical insulation.

Functionalization of multiwalled carbon nanotubes (MWNTs) with biodegradable supramolecular polypseudorotaxanes has been successfully performed by utilizing surface-initiated ring-opening polymerization of ε-caprolactone (CL) to yield poly(ε-caprolactone)-grafted MWNTs (MWNT-g-PCL), followed by forming inclusion complexes between grafted-PCL chains and α-cyclodextrins (α-CDs) to give α-CD-NTPCL hybrids. There are significant differences in the morphology and solubility of MWNTs before and after introduction of α-CD. Some protuberances are clearly observed for α-CD-NTPCL as compared with MWNT-g-PCL. Furthermore, the host–guest stoichiometry (monomeric unit of CL/α-CD molar ratio) for α-CD-NTPCL is much higher than that of polypseudorotaxanes consisted of linear PCL and α-CDs. This observation can be explained by a combination of several reasons including the steric hindrance of grafted-PCL, the competitive exclusion between adjacent PCL chains toward α-CD, and the addition order of α-CD as well as the host–guest feed ratio. The present methodology may open up a new opportunity toward the application of supramolecular chemistry for the chemical manipulation and processing of CNTs. Moreover, such novel supramolecular hybrids provide an entry to extend the applications of CNTs to medicine and biology fields through embedding the functional polymers and heterogeneous components.Functionalization of multiwalled carbon nanotubes (MWNTs) with biodegradable supramolecular polypseudorotaxanes has been successfully performed by utilizing surface-initiated ring-opening polymerization to yield poly(ε-caprolactone)-grafted MWNTs, followed by forming inclusion complexes between grafted-chains and α-cyclodextrins (α-CDs).

By means of distillation precipitation polymerization, the silica-hybrid particles with polyazobenzene shell (PAzo@SiO2) microspheres were prepared with 6-(4-methoxy-4′-oxy-azobenzene) hexyl methacrylate (Azo-M) as monomer, divinylbenzene (DVB) as cross-linker, and ∼250 nm vinylated sol-gel silica particles as template. Hollow polyazobenzene microspheres were further developed after selective removal of the silica cores with HF solution. When the content of DVB related to Azo-M is 20 wt%, the acetonitrile is 200 mL, and the polymerization time is 4.5 h, the hollow PAzo microspheres with about 20 nm shell are successfully fabricated. These hollow PAzo microspheres have excellent reversible photoisomerization, and their first-order rate constant of trans-cis isomerization only decreases 11.8% compared with homopolymer of azobenzene (Homo-PAzo).

A novel ABA triblock copolymer containing electroactive tetraaniline [(ANI)4] and poly(ethylene oxide) (PEO600, Mn = 600), (ANI)4-b-PEO600-b-(ANI)4, was synthesized by coupling tetraaniline and PEO600 with tolylene 2,4-diisocyanate. FTIR, NMR, and UV−vis spectroscopy were combined to characterize the chemical structure of (ANI)4-b-PEO600-b-(ANI)4. The electrochemical properties, self-assembly, and acidity response of copolymer in aqueous solution were investigated by cyclic voltammetry, electron microscopy, and dynamic light scattering. Different from pure tetraaniline and polyaniline, the triblock copolymer in 1.0 M sulfuric acid solution only exhibits one oxidation peak in cyclic voltammetry. In a neutral aqueous solution, the triblock copolymer self-assembled into vesicles with diameter of about 258 nm. Upon acidification with HCl, the size of the vesicles increases to 471 nm and 1.19 μm when the concentration of HCl changes to 10−3 and 10−1 M, respectively. With addition of aqueous 1.0 M HCl to the triblock copolymer solution in THF, hollow spheres and bowl-like aggregates were obtained. A bilayer model was proposed for the vesicle formation, and the mechanism of acidity response was discussed.

Isotactic polypropylene (PP)/nano-magnesium hydroxide (nano-MH) composites with 10 wt.% maleic anhydride grafted styrene–ethylene-butylene–styrene tri-block copolymer (SEBS-g-MA) as a compatilizer were prepared by melt extrusion compounding and injection molding. The effects of SEBS-g-MA on dispersion of nano-MHs in PP matrix and interfacial adhesion were studied in order to prepare highly filled PP/MH nanocomposites. The results showed that SEBS-g-MA improved both dispersion of nano-MHs and interfacial adhesion in PP/MH nanocomposites with up to 40 wt.% nano-MHs. The elastic moduli of PP/SEBS-g-MA /MH nanocomposites increased marginally and tensile yield strengths were almost invariant with nano-MH loading. Significant impact toughening of these ternary nanocomposites was, however, achieved due to the cavitation of SEBS-g-MA/MH particles and expansion of voids as well as plastic deformation of the PP matrix.

In this paper, vinylated magnesium hydroxide (MH) nanosheets were prepared with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and pristine MH nanosheets, then the MH/polystyrene (PS) hybrid nanoparticles were prepared by ultrasonic wave-assisted in-situ copolymerization of vinylated MH nanosheets and styrene (St). The morphology, thermal stability and chemical structure of the final products were investigated in detail with transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared spectra (FTIR). The TEM and FTIR results showed that the uniformly-dispersed core-shell structure of MH/PS nanocomposites with MH-cores and PS-shell was formed. TGA indicated that the covalent interaction between PS and MH improved the thermal stability of PS. A possible formation mechanism of the MH/PS core-shell nanocomposites was also proposed.

Silica-coated multiwalled carbon nanotubes (MWCNTs) have been prepared by the sol–gel polymerization of tetraethoxysilane (TEOS) in the presence of the acid-oxidized MWCNTs at room temperature, followed by oxidizing the MWCNTs templates at high temperature in air to produce hollow silica nanotubes. The thickness and architectures of silica shell were well controlled by rationally adjusting the concentration of TEOS, and by adding cationic surfactant as a structure-directing agent. These results also give a clear answer to prove the fact that the structures of spherical silica particles can be fully “copied” to the coating shell and the wall of silica nanotubes when prepared by the same method as the synthesis of silica particles in the presence of templates.

The self-assembly behaviors of the rod-coil-rod (PANI)98−(PEG)136−(PANI)98 triblock copolymer are investigated in different solvents, such as N-methyl-2-pyrrolidone (NMP), dimethyl formamide (DMF), ethanol and water. The effects of solvents, concentration and ultrasonic irradiation on self-assembly are discussed. The results indicate that the triblock copolymer forms particles, rods, fiber, networks and fiber bands in the above solvents, respectively. Especially, the triblock copolymer can form a multi-layer, tri-dimensional fibrous network and a petaline structure from the mono-layer fibrous network with the increase of its concentration in ethanol. Also, the ultrasonic irradiation has a great effect on the self-assembly of the triblock copolymer.

Polypropylene (PP) /ethylene-octene copolymer (POE) blends with different content of POE were prepared by mixing chamber of a Haake torque rheometer. The crystallization behaviors and crystal structure of PP/POE blends were systematically investigated by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarized optical microscopy (POM). The results showed that PP spherulites became defective and the crystallization behavior was influenced intensely with the introduction of POE. At the low content of POE, the addition of POE decreases the apparent incubation period (Δti) and the apparent total crystallization period (Δtc) of PP in blends due to the heterogeneous nucleation of POE, and small amount of β-form PP crystals form because of the existence of POE. However, at high content of POE, the addition of POE decreases the mobility of PP segments due to their strong intermolecular interaction and chain entanglements, resulting in retarding the crystallization of PP, decreasing in the amount of β-form PP crystals, and increasing in Δti and Δtc of PP in blends.

Poly(ethylene oxide) (PEO) based materials are widely considered as promising candidates of polymer hosts in solid-state electrolytes for high energy density secondary lithium batteries. They have several specific advantages such as high safety, easy fabrication, low cost, high energy density, good electrochemical stability, and excellent compatibility with lithium salts. However, the typical linear PEO does not meet the production requirement because of its insufficient ionic conductivity due to the high crystallinity of the ethylene oxide (EO) chains, which can restrain the ionic transition due to the stiff structure especially at low temperature. Scientists have explored different approaches to reduce the crystallinity and hence to improve the ionic conductivity of PEO-based electrolytes, including blending, modifying and making PEO derivatives. This review is focused on surveying the recent developments and issues concerning PEO-based electrolytes for lithium-ion batteries.

Using the versatility of silica chemistry, we describe herein a simple and controllable approach to synthesise two-dimensional (2D) silica-based nanomaterials: the diversity and utility of the resulting structures offer excellent platforms for many potential applications.

A new structural design and tailored morphology of polymer-functionalized graphene (polymer-FG) are employed to optimize composite polymer electrolytes (CPEs). The ionic transfer conditions including Li salt dissociation, amorphous content and segmental mobility are significantly improved by incorporating polymer-FG, especially that having a polymeric ionic liquid (PIL) and a polymer brush structure [PIL(TFSI)-FGbrush]. Electrical shorts are eliminated due to the presence of the functionalized polymer on reduced graphene oxide (RGO) and a minimal amount of polymer-FG in the PEO/Li+ polymer electrolytes (PEs). Polymer-FG with PIL brushes increases significantly the Li ion conductivity of PEO/Li+ PE by >2 orders of magnitude and ∼20-fold at 30 °C and 60 °C with high Li salt loading (O/Li = 8/1), respectively. Furthermore, significant improvements in mechanical properties are observed where only 0.6 wt% addition of the PIL(TFSI)-FGbrush led to more than 300% increase in the tensile strength of the PEO/Li+ at an O/Li ratio of 16/1. Li-ion battery performance was evaluated with the CPE containing 0.6 wt% of PIL(TFSI)-FGbrush, resulting in superior capacity and cycle performance compared to those of the PEO/Li+ PE. Thus, we believe, embedding minimal amounts of structurally and morphologically optimized polymer-FG nano-fillers can lead to the development of a new class of SPEs with high ionic conductivity for high performance all-solid-state Li-ion batteries.

High diffraction efficiency and low driving voltage are typically considered to be prerequisites for the practical applications of holographic polymer dispersed liquid crystals (HPDLCs), which are especially critical for their use in the state-of-the-art low-threshold mirrorless tunable lasers. Nevertheless, high driving voltages are usually resulted for HPDLCs upon increasing the holographic diffraction efficiency via optimizing the monomer/LC formulations. Herein, we present that doping nanoparticles into HPDLCs with controlled distribution is a facile and efficient approach to circumvent the aformentioned issues. Zinc sulfide (ZnS) nanoparticle doped HPDLCs with high diffraction efficiency (94.0 ± 2.1%), and a low threshold driving voltage of 2.5 V µm−1 that is decreased from 11.6 V µm−1 for the pristine form, are achieved by doping 8 wt% ZnS nanoparticles into the HPDLCs based on an acrylamide monomer, N,N-dimethylacrylamide, that contributes significantly to the high diffraction efficiency up to 98.2 ± 1.4%.