Flame-retardant, non-irritating, and self-healing double-network films based on host–guest interaction were prepared on paper via layer-by-layer (LbL) assembly. The multilayer films are composed of poly (acrylic acid)-adamantanamine/ammonium polyphosphate-cross-poly (ethylenimine)-β-cyclodextrin (PAA-AD/APP-co-PEI-β-CD). After a mild reaction between APP and PEI-β-CD polymers, PAA-AD and APP-co-PEI-β-CD polymers form the novel double-network films via the host–guest interaction. The novel film can produce a self-healing surface without any initiating agents. Besides, when directly exposed to a flame, such films will generate foam char layers because of the intumescent effect, and will endow the print paper with a self-extinguishing property. The fire protection of the coatings was intensively investigated by a fire protection test, scanning electron microscopy (SEM), compressive strength test, thermogravimetric analysis (TGA), and real-time Fourier transform infrared spectroscopy (FTIR). The fire resistant films were found to have the best fire-protection effect under the low-cost and eco-friendly conditions. The films show potential applications as multifunctional advanced commercial supplies, such as papers, textiles, and wood.

•With the help of microfluidic devices that can be full-featured commercial, hollow carbon microspheres with porous structure can be easily mass produced without porogens.•The density and size of pores of polyacrylonitrile(PAN) hollow microcapsules and carbon microspheres can be easily tuned.•PAN-based hollow carbon microspheres can be used as potential porous foam targets with perfect hydrogen barrier properties.Hollow carbon microspheres were successfully fabricated in a convenient fashion by employing polyacrylonitrile (PAN) emulsions as precursors. The obtained hollow carbon microspheres were shown high monodispersity, tunable pore structures—gradient pore diameters and uniform orientation of pores. Through varying the flowing rates of three phases and solidification time, the PAN microspheres with different sizes and densities could be simply synthesized. Besides the relationship between the solidification time and the density of microspheres as well as their gas barrier properties were studied in this paper. These structured microspheres have great potential applications in various areas, including foam targets, carbon molecular sieve, cargo storage, medical instruments and so on.Download high-res image (124KB)Download full-size image

•Self-healing film based on host-guest interaction via LbL was firstly fabricated.•Mechanism of host-guest interaction was explained with computational simulation.•Flexible, acid-resistant and transparent properties were greatly improved.The integration of self-healing ability and mechanical robustness is a challenge in the fabrication of the highly transparent films which are based on host-guest interactions. Beta-cyclodextrin (β-CD) bound with poly (ethylenimine) (PEI) and adamantane (AD) linked with poly (acrylic acid) (PAA) were employed to form a multilayer film based on host-guest interactions via the layer-by-layer (LbL) self-assembly technique. The obtained highly flexible, acid-resistant, self-healing host-guest transparent multilayer film can easily and repeatedly heal external mechanical damage. The PAA-AD/PEI-β-CD multilayer film enhances the transmittance and mechanical properties of PAA/PEI. The average transmittance was approximately 98.6%, and the pre-crack length was approximately 163 mm. The multilayer film can be self-healing because of the rearrangement and reversible host-guest interactions between β-CD and AD, and its practical utility as curable coatings have been demonstrated.

•Film can heal damages with a thickness about hundreds of nanometers.•Reversible thermochromism of the colorful self-healing film is found.•The relationship between the self-healing property and the structure is found.•The self-healing film can discriminate various kinds of metal ions.Inspired by the self-healing ability of plants, we have developed a new form of reversible thermochromic colorful film that can self-heal damages and color under the water stimulation, even with a thickness about hundreds of nanometers. Chitosan (CS) and poly (ethylene glycol) functionalized with the dialdehyde groups (DF-PEG) are employed as the components to fabricate the ultrathin colorful self-healing film via spin-coating method. The performance and mechanism of the self-healing property have been studied in this work. Moreover, a sensory array is built by utilizing the optical property of ultrathin colorful self-healing film. According to their reflective responses, the sensory array is capable of discriminating various kinds of divalent metal ions. The research about the ultrathin colorful film combined with self-healing property promises to greatly widen the future applications of colorful materials.Download high-res image (272KB)Download full-size image

As heavy metals cannot be biodegraded and are easily accumulated in food chain organisms and so enter the human body, a simple detection method becomes particularly important for human health. A robust means for the visual detection of highly toxic mercury ion (Hg2+) is developed with aptamer-functionalized one-dimensional photonic crystals (1DPCs). 1DPCs consisting of TiO2 and poly(N-isopropylacrylamide-acrylic acid), P(NIPAM-AA), were successfully fabricated by a spin-coating technique, whose stopbands span the total visible range. When the 1DPCs were exposed to mercury ion solution, the specific binding of cross-linked single-stranded aptamers and heavy metal ions in the hydrogel network caused the hydrogel to shrink. At the same time, there was a homologous blue shift in the Bragg diffraction peak position of the TiO2/P(NIPAM-AA) 1DPCs. The shift value could be used to estimate the number of target ions quantitatively. It was found that the 1DPCs apta-sensor could screen a wide concentration range of heavy metal ions with selectivity and sensitivity. It is expected that the technology may also be widely used in screening a wide range of metal ions in drugs, food, and the environment.

One-dimensional photonic crystal (1DPhC) was fabricated using a spin-coating method to be utilized as a Bragg reflection mirror. Gold was deposited on 1DPhC films by thermal evaporation under a vacuum. The beta-glucan–fluorochrome complex, whose emission wavelength was largely consistent with the photonic stopband of the 1DPhC, spin coated on the surface of 1DPhC with Au. The fluorescence of beta-glucan–fluorochrome complex deposited on 1DPhCs with Au was obviously enhanced in comparison with that on glass. There was 10-fold fluorescence enhancement. In this study, 1DPhCs with Au were used for the quantitative determination of beta-glucan. Fluorescence spectra demonstrated that a linear relationship existed between the fluorescence intensity and the beta-glucan concentration within 1–6 μg mL−1. The detection limit for beta-glucan is 0.083 μg mL−1 with a sensitivity of 19.53 mL μg−1.

Self-healing materials are gradually being developed because they can restore structural properties and maintain their function after being damaged. Here, branched poly(ethyleneimine) (bPEI), poly(acrylic acid) (PAA), and microcapsules were used to fabricate a functional (bPEI/PAA)*30-microcapsule composite PEM film based on a layer-by-layer (LbL) self-assembly technique. As a proof of concept, the model molecules hydrophilic rhodamine B (RB) and hydrophobic roxithromycin (ROX) were loaded in (bPEI/PAA)*30-microcapsule composite PEM films, and tests with these self-healing films showed them to be endowed with the desired functional properties and hence showed the microcapsules to constitute a promising functional carrier candidate. The results indicated that the microcapsules can be assembled successfully on polyelectrolyte multilayer (PEM) films, and the as-prepared (bPEI/PAA)*30-microcapsule composite PEM film can not only be tailored with desired properties but also show an excellent self-healing ability. Based on our study, we expect more functional molecules to be grafted onto self-healing PEM films using microcapsules and expect functional self-healing PEM composite films to have great potential applications in the future.

•Rare reports are that titania and various organic matters are employed to fabricate uniform porous 1DPhCs.•Fabricate uniform porous 1DPhCs by a green method to solve the limitation of fabricating the 1DPhCs materials.•The method is the simplest, uncontaminated and energy-saving.•The size of the porous 1DPhCs is below 150 nm.•These 1DPhCs have improved about 2.3 times as responding to β-glucan.Porous photonic crystals materials are hot topics, but there are rare reports about which uniform porous titania and various organic matter fabricate one dimensional photonic crystals (1DPhCs) by washing in the condition of a facile low temperature. Solve to the limitation of fabricating uniform porous 1DPhCs materials based on the non-polluting and saving energy, and expand the research area for the need of more applications as well as improves its character. The size of the porous 1DPhCs is below 150 nm. The uniform porous TiO2 and poly N-Isopropy lacrylamide-acrylic acid P(NIPAM-AA) 1DPhCs, the stopbands of which can be made to span the whole visible range, were made by spin-coating technique. The multilayer films became the uniform porous structure after embalmed in water and ethyl alcohol, whose surface topography, lamellar structure and reflectance spectrum were described by the use of SEM and microscope respectively. Finally, we also did some environmental response research works and found that the 1DPhCs have better responsiveness to external temperature and β-glucan. Particularly, these 1DPhCs have improved about 2.3 times as responding to β-glucan than non-porous ones. Fabricating the uniform porous TiO2/P (NIPAM-AA) 1DPhCs by a green method will have great prospect in the future work.Uniform porous titania and various organic matter fabricate one dimensional photonic crystals (1DPhCs) by washing in the condition of a facile low temperature.Download high-res image (96KB)Download full-size image

•It has never reported before 1DPCs/ZnO composite films were fabricated with spin-coating technique.•The fluorescence of the organic dyes deposited on 1DPCs/ZnO composite films was obviously enhanced.•It will be significant for building multilayer films with a simple way for developing the highly sensitive fluorescence detection.One-dimensional photonic crystals (1DPCs)/nanoscaled ZnO particles composite thin films were fabricated with spin-coating technique. Organic dyes, whose emission wavelengths overlap the photonic stopbands of the selected 1DPCs, were deposited on the surface of the 1DPCs films with spin-coating technique. The fluorescence of the organic dyes deposited on 1DPCs/nanoscaled ZnO composite thin films was obviously enhanced in comparison with that on 1DPCs films or ZnO films. Otherwise, the nanoscaled ZnO particles were modified with Poly (sodium 4-styrebesulfonate) (PSS) and Poly (allylamine hydrochloride) (PAH) by self-assembly, and we found a novel phenomenon was observed that the thickness of PSS and PAH had relationship with the effect of fluorescence enhancement. The results show that the 1DPCs/nanoscaled ZnO composite thin films have potential applications in the highly sensitive fluorescence-based detection and optoelectronic devices.

•All the coatings possessed the ability to maintain AA content inner apple slices.•CS-CaCl2 coating was good at anti-browning and quality maintaining.•CS-CaCl2 coated apples have lower weight loss and higher AA content than CS-AA.The consumption of fresh-cut apples has grown rapidly due to consumers’ increasing willingness to enjoy prepared and ready-to-eat fruits. But fresh-cut apples tend to experience severe enzymatic browning which discourages people to taste. Chitosan (CS) coating containing ascorbic acid (AA) or calcium chloride (CaCl2) were applied on fresh-cut apples in this work to observe their preservation effects. Their appearance, weight change were evaluated during the storage at room temperature, besides, AA content, soluble solid content were analyzed at the end of storage. CS-CaCl2 coating has better preservation effect than CS-AA coating when they were applied on fresh-cut apples. CS-CaCl2 coating showed lower weight loss and higher AA content of apple slices than CS-AA coating. CS-CaCl2 coating was also good at anti-browning in terms of the appearance of coated apple slices.

•Three various double emulsions (O1/W/O2) made by the double emulsion stirring method.•Solvent – free PAN hollow microspheres made by the supercritical drying process.•The skin-core structure of Pre-oxidation microspheres is associated with pre-oxidation conditions.•Pre-oxidation microspheres’ have remarkable advantages of pressure-resistance comparing to the plastic ones.•Pre-oxidation PAN microspheres at 300 °C have best mechanical performance than the others.The control PAN plastic microspheres were obtained after the evaporation of the middle solvent from silicon oil/PAN in DMF solution/silicon double emulsions (O1/W/O2) which were prepared with stirring method. The pre-oxidation PAN microspheres were prepared after the heating treatment of the PAN plastic microspheres successfully. The structures of the PAN pre-oxidation microspheres were characterized by the Stereomicroscope, the Field Emission Scanning Electron Microscope (FESEM), and the Fourier Transform Infrared spectroscopy (FTIR). It was found that the pre-oxidation PAN microspheres have best mechanical performance than the others at 300 °C. The pre-oxidation microspheres’ pressure-resistance results showed that they can bear greater pressure than the plastic ones, which means that the microspheres’ mechanical strength has been enhanced after the heating treatment. Most pre-oxidation microspheres can bear the pressure higher than 17 MPa, which provide a great prospect in the target application.The FESEM images of the wall section of PAN pre-oxidation microspheres under different temperatures：260 °C (a)，280 °C (b)，300 °C (c)，320 °C (d)，340 °C (e).

If self-healing materials can be prepared via simple technology and methods using nontoxic materials, this would be a great step forward in the creation of environmentally friendly self-healing materials. In this paper, the specific structural parameters of the various hydrogen bonds between chitosan (CS) and polyacrylic acid (PAA) were calculated. Then, multilayer polyelectrolyte films were fabricated with CS and PAA based on layer-by-layer (LbL) self-assembly technology at different pH values. The possible influence of pH on the (CS/PAA) × 30 multilayer polyelectrolyte film was investigated. The results show that the interactions between CS and PAA, swelling capacity, microstructure, wettability, and self-healing ability are all governed by the pH of the CS solution. When the pH value of the CS solution is 3.0, the prepared multilayer polyelectrolyte film (CS3.0/PAA2.8) × 30 has fine-tuned interactions, a network-like structure, good swelling ability, good hydrophilicity, and excellent self-healing ability. This promises to greatly widen the future applications of environmentally friendly materials and bio-materials.

Low density carbon shells are required in inertial confinement fusion (ICF) experiments. Polyacrylonitrile (PAN), as a common raw material of carbon, was studied and adopted to prepare thick-walled microspheres with the outer diameter ranging from 300 μm to 800 μm; wall thickness around 50–120 μm; sphericity (OOR): <2 μm; and wall thickness uniformity (ΔTw): <9 μm. The preparation of PAN microspheres was based on an assembled double T-junction droplet generator. The major challenge in this experiment was to simultaneously meet the requirements and restrictions on both wall thickness and its uniformity. In order to improve the wall uniformity of thick-walled PAN microspheres, two major factors, the viscosity and the temperature which affect the density-matching solutions between the O1/W compound droplet and the O2 phase, were tested. The calculated results of OOR and ΔTw showed that the optimal density gap between the O1/W compound droplet and the O2 phase would be around 0.015 g cm−3 when the temperature is at 10 °C or the viscosity ratio λ is near 3.6 times (the viscosity ratio λ is defined as the ratio of the W phase to the O2 phase). Under this circumstance, the wall thickness uniformity and sphericity were largely improved. Furthermore, the experiment established that wall thickness uniformity was more sensitive to the temperature and the viscosity than the sphericity.

Hydrogels are environment sensitive and they were introduced to 1DPhCs to improve the sensitivity in our previous research. In this paper, a new method was developed for quantitative determination of beta-glucan in oats by introducing graphene oxide (GO) hydrogels in one-dimensional photonic crystals (1DPhCs) with a polyaniline (PANI) defect layer. GO hydrogels were synthesized via a one-step hydrothermal method, characterized with scanning electronic microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and then they were employed as a component to fabricate 1DPhCs using a spin-coating method. Synthesized 1DPhCs combined with Congo red dye were in use for the quantification of beta-glucan. Reflection spectra demonstrated that a linear relationship existed between the photonic band gap and the beta-glucan concentration within 1–10 mg mL−1. The detection limit for beta-glucan is 0.18 mg mL−1 with a sensitivity of 7.53 nm mL mg−1.

•Hollow polyacrylonitrile(PAN) microcapsules were made by double T-shape devices.•The size of hollow PAN microcapsules can be controlled.•The hollow PAN microcapsules can be applied in inertial confinement fusion project.An off-the-shelf device combined with commercial double T-shape adapters that performs as a micro double emulsion generator was presented in this paper. The advantage of this device lies in that it is assembled very conveniently and the channel needn’t any modification to produce O/W/O double emulsion droplets. High-quality hollow PAN microcapsules were fabricated for the purpose of ICF program through the device. Density-matched three-phase solutions were confected to form stable double emulsions. Initial eccentric double emulsions were able to adjust to be concentric during the process of flowing from the tube to the collection cylinder or self-adjustment during rotary evaporation. When the parameters of three-phase solutions and the tube's diameter were fixed, sizes of the emulsions were mainly related with the flowing velocities of the three-phase solutions. Solidification parameters were optimized to gain high-quality microcapsules. Finally, inner solvent was eliminated with supercritical drying method and the solvent-free targets were obtained. The obtained high-quality hollow microcapsules will have potential application in the ICF program in the future.The illustration of experimental procedures: (a) emulsification (b) solidification (c) supercritical drying.

•bPEI/(PAA-GE) self-healing multilayer polyelectrolyte film was prepared by poly(acrylic acid) (PAA), graphene(GE) and branched poly(ethyleneimine) (bPEI) based on LBL self-assembly technique.•The bPEI/(PAA-GE) self-healing multilayer polyelectrolyte film shows excellent self-healing ability.•The bPEI/(PAA-GE) film has an improved conductive than bPEI/PAA multilayer polyelectrolyte film.Mimicking the nature to confer synthetic materials with self-healing property in order to expand their lifespan is highly desirable and has attracted much more attention from the scientific community. But poor electrochemical property of the fabricated self-healing materials limit the current and future application. Here, self-healing multilayer polyelectrolyte film based on branched poly(ethyleneimine) (bPEI), poly(acrylic acid) (PAA) and graphene(GE) (bPEI/(PAA-GE)) was prepared by layer-by-layer (LBL) self-assembly technique. The bPEI/(PAA-GE) self-healing multilayer polyelectrolyte film not only shows excellent self-healing ability at high humidity, but also possesses good electrical conductivity. It is promised to be applied in battery, supercapacitor or hydrogen fuel cell to improve their cyclic stability and lifetime.

•Three various double emulsions made by one double T-junction microfluidic device.•This device states remarkable advantages comparing to PDMS microchip.•The size of these three double emulsions is associated with the flow rates.•The prepared hollow microspheres shows perfect compact structure.A simple way to prepare water-in-oil-in-water (W1/O/W2) and oil-in-water-in-oil (O1/W/O2) double emulsions which is based on commercial double T-junction tubes was set up, which shows the remarkable advantages of simplicity, operatability and cost-efficiency comparing with the traditional poly(dimethylsiloxane) (PDMS) microchip. By this device, the stable polyacrylonitrile (PAN) microbubbles have also been produced based during the experiments. The success in producing PAN microbubbles provides a new possibility for the preparation of hollow microspheres with polymer materials, which have the further potential applications in numerous particular fields.The preparation of different kinds of hollow microcapsules based on same assembled double T-shape device. The size of hollow microcapsules can be controlled by adjusting the flow rates of the three phases.

Recently, one-dimensional photonic crystals (1DPCs) have attracted considerable interest because they exhibit a material-specific response profile to external stimuli. In our previous work, TiO2/GO 1DPCs, the stopbands of which can be made to span the whole visible range, were fabricated by spin-coating technique. The prepared 1DPCs have a double response to both dimethyl sulfoxide and alkali solution. However, the response is slow, insensitive, and irreversible. To improve the responsiveness of the 1DPCs, poly(ethylene glycol) (PEG)-cross-linked poly((methyl vinyl ether)-co-maleic acid) (PMVE-co-MA) hydrogels were embedded in those crystals. The results demonstrated that modified 1DPCs with different stopbands could be obtained by controlling the speed of the spin-coating technique. The prepared 1DPCs have better responsiveness to external solution pH.Keywords: 1DPCs; DMSO; GO; hydrogel; pH; TiO2

A series of patterning responsive one-dimensional photonic crystals (1DPCs) were developed by using a photolithography technique to etch the template for acidic/alkali vapor sensing by the naked eye through a change in color.

•GE and PAH multilayered films were used to modify the anode in MFCs.•The modification method was based on layer-by-layer (LBL) self-assembly technique.•The modified anodes could produce a higher level of electricity output.•The ITO/(PAH/GE)2 anode electrode could output stable and the highest energy.Microbial fuel cells (MFCs) are bioelectronics devices that can directly convert the chemical energy from organic matter to electricity by the catalytic activity of living microorganisms. The performance of the MFCs could be influenced by many factors, such as anode materials and surface structure. Based on our previous work, in this paper, graphene (GE) nanosheets and poly(allylamine hydrochloride) (PAH) multilayered films were used to modify the anode in MFCs via layer-by-layer (LBL) self-assembly technique. Compared with the bare anode method, the multilayered films could improve the conductive ability between the bacteria and the anode so that produce a higher level of electricity output. The electrochemical performances of anodes modified with different (PAH/GE)n in the MFC were investigated. The results demonstrated that the ITO/(PAH/GE)2 anode produced a much higher and more stable current level. The electrode modified with the (PAH/GE)n is promising for the development of MFCs in the future.

•The preparation method of 1DPCs is a convenient and low-cost method.•The stopbands of TiO2/GO 1DPCs can be tuned in full-color range.•TiO2/GO 1DPCs have a dual responsiveness to organic solvents and pH.1DPCs, such as Bragg stack and distributed Bragg mirrors, are the simplest photonic crystal. TiO2/GO 1DPCs were fabricated by spin-coating technique. The photonic stopbands of the 1DPCs were measured by fiber optic spectrometer. The results demonstrated that the 1DPCs with different stopbands could be obtained from controlling spin-coating and incident angles. The prepared 1DPCs have double response to both dimethyl sulfoxide (DMSO) and alkali solution.

In this paper, we fabricated hollow multilayered polyelectrolyte nanofibers by the combination of the layer-by-layer (LBL) method and electrospinning technique, the hollow nanofibers with an inner hollow diameter about 400–500 nm was obtained while the shell is about 100 nm. The relationship between the morphologies of the obtained dried hollow multilayered fibers and the deposited polyelectrolyte layer numbers was studied. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) were employed to study the obtained hollow multilayered polyelectrolyte nanofibers. Organic/inorganic complex fiber also can be obtained by this method.

Ideally, if the corrosion resistance coating on carbon paper (CP) can be endowed with the self-healing property, the service life and the reliability of the carbon paper will be greatly increased as the gas diffusion layer. In this paper, different cycles of s branched poly (ethyleneimine) (bPEI) and poly (acrylic acid) (PAA) were modified on the surface of the carbon paper via layer-by-layer (LbL) self-assembly technology. The prepared polyelectrolyte multilayered coatings can not only protect the carbon fiber from corrosion, but also take advantages of the surrounding water to quickly repair themselves after damaged. The effects of the assembly cycles on morphology, resistance, air permeability and the contact angle of carbon papers were investigated, then the differences of the carbon papers in electrolysis process were explored. The results reveal that all the prepared coatings can protect carbon papers from corrosion, while when the assembly cycles was 10, the coatings are most efficient.Download high-res image (73KB)Download full-size imageCP presents an irregular increasing time-current curve and the carbon fibers are corroded constantly and seriously at the high potential, while the current curves of (bPEI/PAA)*10-CP has better stability and the carbon fibers are integrated.