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Noble-metal-free surface-enhanced Raman scattering (SERS) substrates have attracted great attention for their abundant sources, good signal uniformity, superior biocompatibility, and high chemical stability. However, the lack of controllable synthesis and fabrication of noble-metal-free substrates with high SERS activity impedes their practical applications. Herein, we propose a general strategy to fabricate a series of planar transition-metal nitride (TMN) SERS chips via an ambient temperature sputtering deposition route. For the first time, tungsten nitride (WN) and tantalum nitride (TaN) are used as SERS materials. These planar TMN chips show remarkable Raman enhancement factors (EFs) with ∼ 105 owing to efficient photoinduced charge transfer process between TMN chips and probe molecules. Further, structural engineering of these TMN chips is used to improve their SERS activity. Benefiting from the synergistic effect of charge transfer process and electric field enhancement by constructing a nanocavity structure, the Raman EF of WN nanocavity chips could be greatly improved to ∼ 1.29 × 107, which is an order of magnitude higher than that of planar chips. Moreover, we also design the WN/monolayer MoS2 heterostructure chips. With the increase of surface electron density on the upper WN and more exciton resonance transitions in the heterostructure, a ∼ 1.94 × 107 level EF and a 5 × 10−10 M level detection limit could be achieved. Our results provide important guidance for the structural design of ultrasensitive noble-metal-free SERS chips.

The fast development of Pickering emulsion systems inspires burgeoning demand on the universal synthesis platform for the surface modification of solid particle emulsifiers. In this work, a mild and convenient “visible light–mediated surface grafting through (VSGT)” strategy is proposed. Through the two-step strategy, silica nanoparticles (SNPs) were firstly modified by vinyl alkoxysilane and then used as the substrate for grafting homopolymer brushes via reversible addition-fragmentation chain transfer polymerization under the irradiation of a compact fluorescent lamp (CFL) light source. The whole process was proceeded at room temperature without tedious conditions and complex operations. Importantly, simply by changing the monomer types, hydrophilic acrylic polymer chains can all be grafted on SNP with controlled chain length and relatively uniform high surface densities including poly(acrylic acid) (PAA), poly(N,N-dimethylacrylamide) (PDMA), poly(N-isopropylacrylamide) (PNIPAM), and poly(diacetone acrylamide) (PDAAM). Through the synthesis platform, the interfacial performance of the surface-grafted nanoparticles exhibited as amendable working as Pickering emulsifiers in oil–water system, illustrated by the evolution of interfacial tensions and the inner structures of the corresponding Pickering emulsions. Moreover, the emulsion stabilized by SNP-g-PAA and SNP-g-PNIPAM showed pH and temperature triggered emulsification-demulsification behaviors, respectively, convincing the contribution of the surface grafted polymers and provide a feasible clue for the subtle design on the interfacial texture in advanced Pickering emulsions.

Van der Waals heterojunctions (vdWHs) provide an excellent material system for the research of heterojunction-enhanced Raman scattering (HERS) due to their complexity and diversity. However, the traditional two-dimensional vdWHs are not conducive to the full utilization of near-field light due to the limitation of single dimension. Herein, we fabricate T-shaped mixed-dimensional SnSe2/ReS2 vdWHs via chemical vapor deposition and wetting transfer method, and demonstrate that the mixed-dimensional vdWHs can be used as ultrasensitive HERS chips based on the effective photo-induced charge transfer. Besides, the radiative energy transfer effect enhanced by near-field light further magnifies the HERS signals, improving the detection limit of rhodamine 6G (R6G) to femtomolar level. Furthermore, we demonstrate that the ultrasensitive screening of crystal violet in multicomponent solutions adsorbed on SnSe2/ReS2 vdWHs can be achieved by adjusting the laser wavelength, which has not been achieved by noble metal materials. This work provides new insights into the mixed-dimensional vdWHs and demonstrates the great application potential of T-shaped heterojunctions.

We propose and demonstrate a flexible surface-enhanced Raman scattering (SERS) chip as a versatile platform for femtomolar detection and real-time interfacial molecule analysis. The flexible SERS chip is composed of a flexible and transparent membrane and embedded plasmonic dimers with ultrahigh particle density and ultrasmall dimer gap. The chip enables rapid identification for residuals on solid substrates with irregular surfaces or dissolved analytes in aqueous solution. The sensitivity for liquid-state measurement is down to 0.06 molecule per dimers for 10-14 mol·L-1 Rhodamine 6G molecule without molecule enrichment. Strong signal fluctuation and blinking are observed at this concentration, indicating that the detection limit is close to the single-molecule level. Meanwhile, the homogeneous liquid environment facilities accurate SERS quantification of analytes with a wide dynamic range. The synergy of flexibility and liquid-state measurement opens up avenues for the real-time study of chemical reactions. The reduction from p-nitrothiophenol (PNTP) to p-aminothiophenol (PATP) in the absence of the chemical reducing agents is observed at liquid interfaces by in situ SERS measurements, and the plasmon-induced hot electron is demonstrated to drive the catalytic reaction. We believe this robust and feasible approach is promising in extending the SERS technique as a general method for identifying interfacial molecular traces, tracking the evolution of heterogeneous reactions, elucidating the reaction mechanisms, and evaluating the environmental effects such as pH value and salty ions in SERS.

With the intrinsic drawbacks of high processing costs, expensive raw materials and poor product-stability, the practical applications of commercial noble metal surface-enhanced Raman scattering (SERS) chips have been severely impeded. Thus, it comes as a significant challenge to develop an uncomplicated preparation method and search for low-cost candidates for highly-sensitive commercial SERS chips. Herein, we come up with a facile and universal approach to fabricate a series of plasmonic metal carbide SERS chips. This is the first time that tungsten carbide, molybdenum carbide, and niobium carbide are reported as SERS materials with cheap prices. Furthermore, we prove that the high SERS activity of these materials comes from strong localized surface plasmon resonance effects. These metal carbide chips could realize the detection of diverse organic molecules, and the detection limit concentration of rhodamine 6G was found to be below 10−8 M, which is even lower than some of the noble metal SERS substrates. Our work provides an efficient strategy to upgrade the industries of commercial SERS chips.

Efficient photoinduced charge transfer (PICT) resonance is crucial to the surface-enhanced Raman scattering (SERS) performance of metal oxide substrates. Herein, we venture into the hot-electron injection strategy to achieve unprecedented enhanced PICT efficiency between substrates and molecules. A heterojunction array composed of plasmonic MoO2 and semiconducting WO3-x is designed to prove the concept. The plasmonic MoO2 generates intense localized surface plasmon resonance under illumination, which can generate near-field Raman enhancement as well as accompanied plasmon-induced hot-electrons. The hot-electron injection in direct interfacial charge transfer and plasmon-induced charge transfer process can effectively promote the PICT efficiency between substrates and molecules, achieving a record Raman enhancement factor among metal oxide substrates (2.12 × 108) and the ultrasensitive detection of target molecule down to 10-11 M. This work demonstrates the possibility of hot-electron manipulation to realize unprecedented Raman enhancement in metal oxides, offering a cutting-edge strategy to design high-performance SERS substrates.

The manipulation of nanobuilding blocks into a 3D macroscopic monolith with ordered hierarchical structures has been much desired for broad and large-scale practical applications of nanoarchitectures. In this paper, we demonstrate a fully bottom-up strategy for the preparation of aramid aerogel monoliths. The process starts from the synthesis of poly(p-phenylene terephthalamide) (PPTA) through the polycondensation of p-phenylenediamine and terephthaloyl chloride, with the assistance of a nonreactive dispersing agent (polyethylene glycol dimethyl ether), which helps the dispersal of the as-synthesized PPTA in an aqueous medium for the formation of p-aramid nanofibers (ANF). Then the vacuum-assisted self-assembly (Vas) technique is skillfully connected with the ice-templated directional solidification (I) technique, and the combined VasI method successfully tailors the self-assembly of ANF to transform the 1D nanofibers into a 3D aerogel monolith with a specific long-range aligned, lasagna-like, multilaminated internal structure. The study of the aerogel microstructure revealed the dependence of the lamina orientation on the direction of the freezing front of ice crystals. This direction should be parallel to the deposition plane of the Vas process if a long-range aligned lamellar structure is desired. The anisotropy of the multilaminated aerogel was proven by the different results in the radial and axial directions in the compression and thermal conductivity tests. As a kind of organic aerogel, the ANF monolith has typical low density, high porosity, and low thermal conductivity. Additionally, the ANF monolith exhibits high compressive stress and excellent thermal stability. Considering its high performance and facile preparation process, potential applications of the ANF aerogel monolith can be expected.

Surface-enhanced Raman spectroscopy (SERS), a sensitive analytical technique that has single molecular sensitivity, has attracted continuous attention for both application and academic research. Semiconductor-based substrates with SERS activity present more practical applications, ranging from surface science to biological detection because of their lower cost and better biocompatibility compared with noble metals. However, the SERS performance of most semiconductor-based substrates is not significant. Herein, we propose the concept of semiconductor heterojunction-enhanced Raman scattering and design a vertical nanothickness heterojunction of W18O49/monolayer MoS2. As a result, the Raman signals of analyte Rhodamine 6G are detectable even with an ultralow concentration of 10-9 M on W18O49/monolayer MoS2 substrates. The enhancement factor is around 3.45 × 107. We confirmed from experiments and theory that the coupling of these two semiconductor materials could lead to dramatic enhancement of photoinduced charge-transfer processes, which enables giant heterojunction-enhanced Raman scattering.

The building of polymer composite particles in their confined colloidal-scale space is a highlighted topic, leading to advanced structure complexity and high performance in functional coating applications. Here, we demonstrate a direct emulsion polymerization (EP) approach to synthesize composite latex with hindered phenol (HP), a kind of functional small molecules, successfully loaded inside colloidal polymer particles. Monomer conversion as well as the evolution of droplet/particle size has been traced as a function of polymerization time. The results evidence the smooth running of the polymerization process with high HP loading in situ in the aqueous dispersion which could reach 30 phr. As-synthesized HP/polymer latex could be conveniently used for the formation of coating films. The films are unique for the greatly improved damping properties. With HP content of 30 phr, the effective damping temperature range can be broadened to 112 ℃, and the a maximum loss factor can rise to 2.7. The weak hydrogen bonding is found to be the key for the incorporation of HP with the polymer segments, and contributes to the dissipation of vibration energy in the films. Combined with the environmental benefits, waterborne composite latex here is of potential application for the building of green damping coating systems.

Functional microspheres with subtle designed molecular recognition sites is much highlighted in recent days. We here study the in situ molecular imprinting in the Stober synthesis of resorcinol-formaldehyde (RF) microspheres, and two different approaches are demonstrated. One approach is named as organic molecular imprinting, during which the target molecules of bisphenol A (BPA) are incorporated as the template in the gelation of RF resin. The other is named as inorganic molecular imprinting, during which the template is introduced together with inorganic precursor of titanate. The sizes of the produced spheric particles are found to rely on the ratio of ethanol/water in the reaction medium. Recognition sites which are BPA specific have been detected on both the RF and RF-carbon/TiO2 spheres, and the latter show slightly higher capacity and selectivity in rebinding tests. Importantly, the integration of the photo active nano TiO2 on the submicron spheric carbon support with BPA imprinted sites is of unique advantages, which exhibits as the specific high photocatalytic efficiency on BPA degradation under UV light. This, together with the high selectivity, substantial efficiency and operable uniform size of the composite spheres would be useful in the engineering for environmental and analysis fields.

Surfactant-free visible-light-controlled emulsion polymerizations are demonstrated here to synthesize ABA-type amphiphilic triblock copolymers, where A represents the hydrophilic block of poly(acrylic acid) (PAA) and B represents the hydrophobic block, such as poly(butyl acrylate) (PBA), poly(ethyl acrylate) (PEA), poly(trifluoroethyl acrylate) (PTFEA), and poly(hexafluorobutyl acrylate) (PHFBA). The photoiniferter solution polymerization of acrylic acid (AA) in 1,4-dioxane was first performed under air atmosphere and successfully controlled by visible light with the existence of iniferter agent and ascorbic acid. Using the as-synthesized PAA with trithioester end-groups as macro-iniferter agent, ABA-type triblock copolymers were synthesized in an aqueous emulsion system. Chain growth of various hydrophobic B blocks induced self-assembly and micellization. The micelles were in turn swelled by monomers and acted as main reaction loci for the further photoiniferter emulsion polymerizations. All the polymeri...

As one of the most important organic semiconductors, perylene diimide derivatives (PDIs) have been widely applied in optoelectronics. Two kinds of soluble PDIs with different imide substituents have been synthesized and their optical properties have been investigated. The photoluminescence (PL) intensity of the PDI with amino phenyl imide substituents (NH2 -PDI) is much lower than that of the PDI with octyl imide substituents (O-PDI). It can be found that the Stokes shift of O-PDI is positive, whereas, the Stokes shift of NH2 -PDI is negative. The emission intensity of the 0-0 electron transition relative to that of the 1-0 electron transition (I0-0 /I1-0 ) in the PL spectrum of O-PDI is decreased, but the value of I0-0 /I1-0 in the PL spectra of NH2 -PDI is increased as the dielectric constant of the solvent increases. The large overlap between the absorption and PL spectra plays an important role to result in the low PL intensity of NH2 -PDI. The PL decay data show that a non-radiative process, photoinduced electron transfer, also contributes to the low PL intensity of NH2 -PDI. The results can help researchers to understand the effect of the imide substituents on the optical properties of PDIs.

Proper building of polymer/polysilsequioxane composite is determined by deep-rooted structural variables. This work focuses on the fabrication of silane-grafted waterborne polyurethane (DWPU)/polyphenylsilsequioxanes (PPSQ) composites by blending and in-situ methods, respectively. By using blending method, PPSQ nanoparticle latexes were dispersed in DWPU. By using in-situ method, as the precursor of PPSQ, phenyltrimethoxysilane was mixed in DWPU, and PPSQ was expected to be generated via in-situ sol-gel reaction during film formation. We systematically investigated the influences of PPSQ and its incorporation method on the phase separation of films. The competition between a heterophase-triggered phase separation and a silane-based crosslinking was found during film formation. The intrinsically local ordering permutation of PU segments was interrupted more or less with PPSQ. Both surface composition and morphology were altered in correspondence to the different addition amount of PPSQ. Furthermore, optical, mechanical, and thermal resistances of composite films were also investigated for potential applications as coatings.

We have synthesized a multi-functional copolymer poly(N-isopropylacrylamide) (PNIPAM) containing rhodamine 6G and 1,8-naphthalimide moieties via reversible addition-fragmentation chain transfer (RAFT) radical polymerization. In a neutral condition, only an emission band with a peak at 520 nm is observed in the copolymer, which originates from 1,8-naphthalimide. The 520-nm photoluminescence (PL) intensity is markedly increased with decreasing the pH value of Britton-Robinson buffers, but changed instinctively by the concentration of Fe3+. The spirolactam ring-opening of the rhodamine 6G moiety is responsible for the PL changes of the copolymer in acidic conditions and Fe3+ aqueous solution, correspondingly, the 555-nm PL band of rhodamine 6G can be found for excitation at 400 nm. The PL intensity at 555 nm relative to that at 520 nm (I555/I520) is dependent on the resonance energy transfer from 1,8-naphthalimide to rhodamine 6G, which can be controlled by the chain conformations of the themoresponsive copolymer. The good linear relationships between the PL changes and the detection objects mean that the copolymer can be served as ratiometric chemosensors to probe pH, Fe3+ ions and temperature.

In this work, we demonstrate a miniemulsion polymerization strategy to synthesize molecularly imprinted polymer (MIP) submicron particles. Bisphenol A (BPA), an endocrine disrupting chemical, is chosen as the template molecule. The template was dissolved in the mixture of the functional monomer and crosslinking agent. The monomer mixture was emulsified into miniemulsion with the droplet diameter of about 100 nm via sonication. The specific sites were immobilized into polymer particles through the radical polymerization in the droplets. After the extraction of the template, MIP particles were obtained with an average diameter of 138 nm. The formation of recognition sites on the particles was validated by the excellent binding capability towards BPA in the selective and competitive binding experiments. Benefited from the small particle sizes and large surface areas, the MIP particles exhibit accelerated adsorption kinetics. The particles with submicron sizes, excellent BPA recognition accuracy and rebinding efficiency would be attractive in environmental and analytic fields for BPA decontamination.

Graphene has been extensively concerned as an ideal modifier in the exploration on mordern polymer coatings with high performance. However, the poor dispersibility of graphene in water strongly limits the application in waterborne systems. Here, we demonstrate a simple but effective reduction–coagulation method for the preparation of hybrid nanoparticles of halloysite nanotubes (HNTs) and reduced graphene oxide (rGO). The work was started from the simple mixture of the aqueous dispersion of graphene oxide(GO) and HNTs. As the subtle introduction of the reducing agent, GO was reduced into rGO and co-coagulated with HNTs. Tailored by the residual hydrophilic groups inside the nanotube of HNTs, the phase separation was controlled in colloidal scale, and stable aqueous dispersion of HNTs–rGO hybrid nanoparticles was thereafter obtained conveniently. We directly blended the product into the polymer latex for the formation of coating films. The tests reveal that the composite coating system with the addition of...

How to on-line analyze the morphology of composite polymer particles is a great challenge to develop the high-performed polymer nanoparticle materials, not only academia aspect but also industrial applications. We aim to on-line detect the weight fraction of each phase in composite polymer particles with a multilayered structure during emulsion polymerization. This work is also hoped to contribute to the development of on-line analysis on the morphology of composite polymer particles in the future. The weight fractions of core phase, interfacial layer, and shell layer (Wc, Wi, and Ws, respectively) in the multilayered composite polymer particles prepared by semi-continuous seeded emulsion terpolymerization of styrene (St), butyl acrylate (BA), and methyl methacrylate (MMA) with the existence of St-BA copolymer seed particles were successfully analyzed by using on-line near-infrared (NIR) spectroscopy for the first time on the basis of the results obtained by multi-frequency temperature-modulated differential scanning calorimetry (TOPEM-DSC), where NIR calibration models on Wc, Wi, and Ws were successfully established. By using NIR spectroscopy and the established models, the values of Wc, Wi, and Ws could be accurately on-line detected. It is suggested that there is a possibility to estimate the formation of unique morphology in composite polymer particles by on-line NIR measurement.

The design and fabrication of polymer microspheres with structural complexity in Pickering emulsion systems is a pioneering topic in recent years. Herein we report a synthesis of structured and molecularly imprinted multicore rattle-type microspheres through a facile method based on the Pickering emulsion polymerization using silica nanoparticles as the only stabilizer. The void inside the sphere was induced by the polymerization-driven phase separation approach tailoring by the interface interaction. However, the imprinting template of bisphenol A (BPA) is found to serve also as the heterogeneous nuclei, whose superimposition on the polymerization induced phase separation creates the opportunities for the formation of the multicores encapsulated in the shell. A simple adjustment on the composition of the oil phase enabled the evolution of sphere internal structures from single void to multicores. Specifically, the reversibly incorporated BPA on the polymer spheres can be removed by extraction with the molecular information left and immobilized by crosslinking as the imprinted sites. The imprinted spheres can be used to selectively rebind BPA, which was comprehensively evaluated by a batch of rebinding experiments. The rattle-like microspheres recognized BPA molecules from their analogues and effectively removed them from the matrix with accelerated adsorption kinetics, which shows potential applications in the environmental or analytic fields where the removal or separation of BPA as an endocrine-disrupting chemical is in high demand.

The recent researches on waterborne polyurethane (WPU) have been much highlighted to fulfill the both requirements of environment and material performance. Herein, a simple copolymerization approach is demonstrated toward the tough, fluorescent and adhesive WPU elastomer films by the incorporation of para aromatic amide (aramid)-urea segments in the backbone of the polymer. The synthesis of the poly(amide-urea-urethane) was carried out through two steps of chain extension reactions, and the aramid motif, 4,4'-diaminobenzanilide (DABA) was used as the chain extender in the second step of chain extension before the polymer was neutralized and dispersed in water. The aramid-urea segments promoted the H-bonding association of the polyurethane matrix during the film formation of the WPU, which facilitated the microphase separation as well as the pronounced elevation of film performance. Under the DABA content of 4 wt%, the ultimate tensile strength increased to 73 MPa, 380% of that without DABA incorporation. Importantly, the WPU film showed remarkable toughness of 372 MJ·m-3 with the elongation at break of ~1250%. The water adsorption of the film was also suppressed to below 3% in 24 h of the water uptake test. Not only that, but the elastomer film also exhibited high adhesion to metal surfaces to withstand a hanging weight of 27.5 kg with the bonding area of 25 mm × 50 mm. Besides, the film was also able to emit bright blue fluorescence under the excitation of UV light. The combining of high strength, toughness, water resistance and photoluminescence in the WPU will provide the elastomer great potential as environmentally friendly multifunctional material.

To develop highly sensitive, stable and repeatable surface-enhanced Raman scattering (SERS) substrates is crucial for analytical detection, which is a challenge for traditional metallic structures. Herein, by taking advantage of the high surface activity of 1T' transition metal telluride, we have fabricated high-density gold nanoparticles (AuNPs) that are spontaneously in-situ prepared on the 1T' MoTe2 atomic layers via a facile method, forming a plasmonic-2D material hybrid SERS substrate. This AuNP formation is unique to the 1T' phase, which is repressed in 2H MoTe2 with less surface activity. The hybrid structure generates coupling effects of electromagnetic and chemical enhancements, as well as excellent molecule adsorption, leading to the ultrasensitive (4*10^-17 M) and reproducible detection. Additionally, the immense fluorescence and photobleaching phenomena are mostly avoided. Flexible SERS tapes have been demonstrated in practical applications. Our approach facilitates the ultrasensitive SERS detection by a facile method, as well as the better mechanistic understanding of SERS beyond plasmonic effects.

We report on design and fabrication of patterned plasmonic dimer arrays by using an ultrathin anodic aluminum oxide (AAO) membrane as a shadow mask. This strategy allows for controllable fabrication of plasmonic dimers where the location, size, and orientation of each particle in the dimer pairs can be independently tuned. Particularly, plasmonic dimers with ultrasmall nanogaps down to the sub-10 nm scale as well as a large dimer density up to 1.0 × 1010 cm–2 are fabricated over a centimeter-sized area. The plasmonic dimers exhibit significant surface-enhanced Raman scattering (SERS) enhancement with a polarization-dependent behavior, which is well interpreted by finite-difference time-domain (FDTD) simulations. Our results reveal a facile approach for controllable fabrication of large-area dimer arrays, which is of fundamental interest for plasmon-based applications in surface-enhanced spectroscopy, biochemical sensing, and optoelectronics.

The direct synthesis of polymer microspheres modified by aramid nanofibers (ANFs) is an interesting challenge. This work describes a simple aqueous process to prepare polystyrene (PS)/ANF composite microspheres, where the specific ANF network was "dressed" on PS. ANF was derived from the copolymerization of terephthaloyl chloride, p-phenylene diamine, and methoxypolyethylene glycol and could be dispersed in water stably. We applied the as-synthesized ANF as a Pickering emulsifier in the o/w emulsion of styrene monomer. Radical polymerization was subsequently initiated in the Pickering emulsion system. The combination of ANF with polymer spheres was revealed by scanning electron microscopy (SEM) and thermal gravity analysis. The role of ANF in the monomer emulsion as well as in the polymerization was studied through SEM, optical microscopy, optical stability analyzer, and pulse nuclear magnetic resonance combined with the polymerization kinetic analysis. Moreover, we investigated the effects of other synthesis parameters, such as monomer type, monomer content, pH value, and salt concentration.

The adsorptive materials which have the function of molecular recognition are becoming important as the fast emerging environmental requirements for the analysis and repair of target contaminants present at low concentrations in aqueous matrices. Here, we demonstrate a Pickering emulsion polymerization strategy to build bisphenol A (BPA) imprinted poly(methacrylic acid) microspheres without the traditional organic surfactant. In the synthesis, the only stabilizer is silica particles derived from Stober process. The molecularly imprinted polymer microspheres were prepared by radical polymerization in the Pickering oil/water emulsion. Both the solid stabilizers and the molecular templates were conveniently removed from the microspheres. The obtained microspheres are of regularly spherical structures and hydrophilic surfaces. The formation of molecularly imprinted sites on the microspheres was validated by the excellent recognition capability toward BPA in the rebinding and competitive binding experiments.

In order to enhance photocatalysis by broadening light harvesting, bundled TiO2 nanowire bundle arrays are encapsulated with indium tin oxide (ITO) by a self-assembly technique involving anodization, electrochemical etching, and ITO deposition. The plasmonic photocatalyst, which has a multiscale structure with variable nanoscale gaps as well as microscale funnels, shows broadband localized surface plasmon resonance absorption of 84% in the wavelength range between 400 and 2500 nm. The improved photocatalytic efficiency is demonstrated by methyl orange degradation under sunlight illumination. The improvement stems from enhanced light harvesting arising from the localized surface plasmon resonance of the ITO membrane which extends the light response to the visible and NIR regions and excites hot charge carriers.

A clean method for preparing ABCBA penta-block terpolymers was developed in a surfactant and organic solvent free emulsion system via one-pot RAFT polymerization. The prepared ABCBA penta-block terpolymers show large fracture tensile strain, low permanent set and potential application as elastomer materials. During the preparation process, polyacrylic acid (PAA) was firstly synthesized as the A block via RAFT polymerization in water in the presence of a dual-functional RAFT agent. Subsequently, we selected a partially water-soluble monomer 2,2,2-trifluoroethyl acrylate (TFEA) to synthesize the B block, and ABA tri-block copolymers could be obtained via organic solvent free RAFT emulsion polymerization. Using the ABA tri-block copolymers as a surfactant, the ABCBA penta-block terpolymers were further synthesized using 2,2,3,4,4,4-hexafluorobutyl acrylate (HFBA) as the third monomer in an organic solvent free system. It has been found that the emulsification efficiency of the ABA tri-block copolymers is higher than that of the corresponding AB di-block copolymers. The assembly mechanism of penta-block terpolymers to form a tri-layer core–shell latex particle was proposed and confirmed by TEM images. Finally, we obtained a transparent and hydrophobic elastomeric film by directly casting the synthesized penta-block terpolymer latexes and subsequent heat treatment. The films have excellent mechanical properties and water resistance.

Stability of the structure and redox state of ferricytochrome c during continuous changing of the hydration environment from dilute solution to condensed phase was studied based on real-time resonance Raman measurement. Our experimental results indicated that the structure and redox state of ferricytochrome c were sufficiently maintained during the entire desolvation process, which reflected that the stabilizing excluded-volume effect was stronger than the destabilizing crowder-protein interaction, at the case of globular mini-protein itself acting as the crowder. Rapid reduction of ferricytochrome c was observed at measurement sites at the time of solution to condensed phase transition. Similar phenomenon was observed on cytochrome c adsorbed on indium tin oxide surface. At present conditions, the rapid reduction was found to be derived mainly from thermal reduction under laser illumination and secondarily from photoreduction induced by the residual adsorbed ferrocyanide anions. After re-dissolved, the protein which had undergone sufficient desolvation recovered the structure and redox state in the initial solution phase, suggesting that the crowding effect in solution prevented large protein deformations observed in gas phase condition.

A feasible co-endcapping strategy has been developed for the synthesis of monofunctional polyhedral oligomeric silsesquioxanes (POSS) modified waterborne polyurethane (WPU). The work starts from the synthesis of di-isocyanate terminated PU prepolymer from isophorone di-isocyanate (IPDI), poly (1,4-butylene adipate) end-capped diol (PBAD), and 2,2-bis(hydroxymethyl) butyric acid (DMBA). The two kinds of modifiers of monofunctional aminopropyl isobutyl POSS (AIPOSS) and with (3-aminopropyl) triethoxysilane (APTES) were used together to block the PU chains. The hybrid dispersions of curable silane-co-modified WPU with 2–8 wt% of AIRPOSS could form continuous and homogenous films under ambient conditions. The morphology and structure of the dispersed particles and the films were characterized, as well as the mechanical property and surface performance. The results indicate that the incorporation of POSS moieties into the silane-modified PU can significantly improve the mechanical property of the films and the formation of additional physical crosslinking points upon the chemical crosslinking networks. Moreover, both the surface hydrophobicity and the dielectric performance have been promoted by the incorporation of POSS. Furthermore, fluorinated groups were introduced on the films by the treatment of the fluorosilane coupling agent. The fluoro-POSS-PU hybrid films exhibit notable surface hydrophobicity as well as low dielectric constant and loss.

A series of waterborne polyurethane (WPU) containing alkoxysilane side groups were synthesized by using the dihydroxy functionalized alkoxysilane. The diol with trimethoxysilane groups at the side chains was synthesized via Michael addition between 3-(methacryloxypropyl)trimethoxysilane (MAPTS) and diethanolamine (DEA). The silane diol was applied as the chain extender for the NCO-endcapped prepolymer of isophorone diisocyanate, polycarbonate diol, 2,2-bis(hydroxymethyl) butyric acid and 1,4-butanediol. The products with the silane content varied from 1.2 to 16.5 wt% were dispersed in water after neutralization. The effect of the silane diol on the particle size and morphology of the WPU dispersion was studied by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. X-ray photoelectron spectroscopy (XPS) characterization was carried out on the coating film of the WPU, revealing that the long flexible side chain is favorable for the silane components to emigrate toward the film surface and crosslink during the film formation process. As a result, both the surface contact angle to water and water adsorption of the WPU coating films increased with the silane content. Furthermore, the mechanical properties including the modulus and tensile strength of the films were also improved by the incorporation of silane diol.

Styrene (St) and maleic anhydride (MA) alternating copolymers with different molecular weights (MW) were synthesized via radical copolymerization. The copolymers were subsequently transferred into water-soluble maleic amic acid derivatives (SMAA) via the aminolysis of anhydride groups using (NH4)2CO3 as the ammonia sources. The synthesized polymers were applied as a new kind of macromolecular modifier and added into the reaction system during the synthesis of urea-formaldehyde (UF) resins via the traditional alkaline–acidic–alkaline three-step process. The UF resins modified with SMAA were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), 13C nuclear magnetic resonance (13C-NMR) spectroscopy, and thermal gravimetric analysis (TGA). All the results confirmed the successful incorporation of SMAA chains into the crosslinking network of the UF resins. The modified UF resins were further employed as wood adhesives and the effect of synthesis parameters on their performance was investigated. Meanwhile, the influence of SMAA molecular weight (MW) on the properties of the modified UF resins was also studied. When the UF resins were synthesized with a low molar ratio of formaldehyde/urea (F/U) and a predetermined amount of SMAA added into the reaction system at the second step, plywood bonded using these modified UF resins showed much improved bonding strength (BS) and depressed formaldehyde emission. Moreover, the as-modified UF resins showed good storage characteristics.

Poly(p-phenylene terephthalamide) (PPTA) nanofibers were prepared via a polymerization induced self-assembly process with the assistance of methoxy polyethylene glycol (mPEG) for stability and dispersity. In the traditional process of the solution polycondensation of p-phenylenediamine (PPD) and terephthaloyl chloride (TPC), PPTA will aggregate and precipitate with the chain growth due to the liquid crystalline characteristic. The introduction of mPEG can control the aggregation degree of PPTA molecules and stabilize the formed aggregates, which drives the self-assembly of PPTA molecules and results in the formation of nanofibers. The obtained nanofibers specialized by the great length–diameter ratio were characterized in detail. The effects of mPEG addition on the formation and the performance of the fibers were all studied in the work. The nanofibers can disperse in variety of organic solvents and water. Moreover, the nanofibers can be deposited for the formation of thin films with excellent transparency and thermal stability, which has great potential applications such as the separator of lithium ion battery.

We report a convenient nanotechnique to fabricate indium tin oxide (ITO) capped titanium dioxide (TiO2) nanolace arrays for plasmonic photocatalysis. The topography can be tuned to optimize the photocatalytic efficiencies by adjusting the anodic voltage or the time of ITO magnetron sputtering. Microstructural analysis and finite difference time domain simulations indicate the generation of ITO surface plasmon resonance in the near-infrared region and ITO–TiO2 heterojunctions. The enhanced photocatalytic performance of such ITO–TiO2 composite nanostructures could spur further interest in the utilization of the near-infrared region for plasmonic photocatalysis.

A facile method for preparing ABA tri-block functional elastomers via two-step RAFT emulsion polymerization is introduced in this work. Poly(acrylic acid)-b-poly(2,2,3,3,4,4,4-hexafluorobutyl acrylate)-b-poly(acrylic acid) (PAA-b-PHFBA-b-PAA) tri-block copolymers were synthesised, and transparent films were obtained by directly casting the synthesized latexes. The water contact angle (WCA) of the as-prepared films was dramatically improved after heat treatment at 120 °C for 4 h, and the films were changed from hydrophilic to hydrophobic. By using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), the surface structure of the films was investigated in this work, to illustrate the mechanism of the variation in the surface properties of the films upon heat treatment. Moreover, the synthesized tri-block copolymers behave as elastomeric materials, with a high elongation at break of around 1200% and a permanent deformation of below 25%.

Polypyrrole–polystyrene (PPy–PS) composite hollow microspheres with a dry-plum-like morphology were prepared via pseudo-multicomponent heterophase polymerization in an aqueous dispersion system. The monomers of pyrrole (Py) and styrene (St) were simultaneously added into the reactor with the existence of azodiisobutyronitrile. The oxidization polymerization of Py was first initiated by the addition of ammonium persulfate, and the radical polymerization of St was subsequently initiated by the elevated temperature. Finally, composite micron-sized spheres were obtained with hierarchical structures. The microspheres are hollow inside, with PPy nano-particles bound by a PS matrix for the building of the wall-shell. The decoration of tiny PPy particles at the surface leads the microspheres to be an effective adsorbent to isolate Cr(VI) ions from water. The adsorption kinetics and isotherm result of the microspheres agree well with the pseudo-second-order rate model and Langmuir isotherm mode, respectively.

The fixation of atmospheric dinitrogen to ammonia is one of the most essential processes for sustaining life. Since the N N bond in dinitrogen is one of the strongest bonds in chemistry, it remains a grand challenge to develop efficient catalysts for fixation of N2 under ambient conditions. Herein we report for the first time on visible-light-assisted photocatalytic nitrogen fixation by metal organic framework material at room temperature and pressure. The Ti3+ species induced by electron transfer from ligand-to-metal charge transfer process provide active sites for N2 reduction. Furthermore, visible-light-assisted photocatalytic N2 fixation is achieved by ligands functionalization which extend the light harvesting of the MOF to visible region. The integration of Ti sites and amine-functionalized linkers in NH2-MIL-125 (Ti) shows the highest visible light photocatalysis efficiency at a rate of 12.3 μmol g−1 h−1. This Ti MOF system therefore shows a potential as a new design of combining light-harvesting and catalytic components in a single solid platform for green NH3 production.

Inspired by the growing demand for smart and environmentally friendly polymer materials, we employed 2,2&prime, disulfanediyldianiline (22DTDA) as a chain extender to synthesize a waterborne polyurethane (WPUR). Due to the ortho-substituted structure of the aromatic disulfide, the urea moieties formed a unique microphase structure in the WPUR, its mechanical strength was enhanced more 180 times relative to that of the material prepared without 22DTDA, and excellent self-healing abilities at body temperature in air or under ultrasound in water were obtained. If the self-healing process was carried out at 37 &deg, C, 50 &deg, C or under ultrasound, the ultimate tensile strength and elongation at break of the healed film could reach 13.8 MPa and 1150%, 15.4 MPa and 1215%, or 16 MPa and 1056%, respectively. Moreover, the WPUR films could be re-healed at the same fracture location over three cutting&ndash, healing cycles, and the recovery rates of the tensile strength and elongation at break remained almost constant throughout these cycles.

Graphene exhibits great potential as a functional building block in modern protective material aiming to high anti-corrosion performance. Herein, we demonstrate a concept for graphene based integrated intelligent inhibitor nanocontainer (IIIN), which can provide multifunctional anti-corrosion protection when be applied as a modifier in waterborne coating. The synthesis of IIIN was started from the nanocomposite of halloysite nanotubes (HNTs) and reduced graphene oxide (rGO). Then, L-histidine (L-His) was loaded on HNTs-rGO for the formation of ternary nanocomposite via electrostatic adsorption. IIIN has the excellent compatibility with waterborne coatings. Importantly, L-His@HNTs-rGO can provide an integrated anticorrosion function: in addition to the role of “passive protection” of rGO, IIIN not only extends the diffusion distances of the corrosive molecules, interrupts the possible formation of conductive pathways, but also serves an intelligent container to release L-His. The comprehensive result is the effective prolongation on the protection life of the coating from 7, 67 and 22 days of the unmodified waterborne coating, to 42, 116, and 69 days of the IIIN modified coating in H2SO4, NaOH, NaCl solution respectively. The electrochemical impedance spectroscopy (EIS) has been applied to monitor the corrosion process for different coatings, which confirms the synergism effect of IIIN.

As a powerful analytical tool of molecular detection, surface-enhanced Raman spectroscopy (SERS) has attracted great attention in varied fields. However, it has seriously impeded the development of SERS that the preparation process is generally complicated and traditional substrates lack eco-friendliness, economy and flexibility. Herein, we fabricated the inkjet-printed paper-based semiconducting SERS substrates for the first time via an inexpensive office inkjet printer with representative two-dimensional MoO3-x nanosheets ink. Compared with conventional substrates, these paper-based semiconducting substrates not only could meet the requirements of simple and large-scale preparation, but also realize efficient sample collection by merely swabbing the surface. We obtained the detection limit concentration of rhodamine 6G as low as 10-7 M. Furthermore, these flexible paper-based substrates were successfully applied to detect crystal violet and malachite green on the fish surface by swabbing. With immense potentiality in practical applications, the inkjet-printed paper-based semiconducting SERS substrates are expected to open a new prospect for SERS.

The conformations and redox states of ferricytochrome c, before and after adsorption onto the surface of the indium tin oxide (ITO) nanoparticles, are studied to reveal the interaction nature between the cytochrome c and the conducting metal oxide surface. The characterizations with resonance Raman scattering and UV–Vis absorption reveal that the change of pH at moderate ionic strength induces transitions of conformations and redox-states, which suggests that there is intramolecular electron transfer. The conformations of the cytochrome c species are maintained after adsorption onto or collision with the ITO surface, but the redox states change significantly, and the change depends on the surface structure of the ITO nanoparticle. The adsorption or collision processes are governed by the pH-dependent electrostatic interaction between the proteins and the buffer anions bound to the ITO surface. This adsorption scenario differs from the conventional ones.

Polycaprolactone (PCL) networks with disulfide bonds are synthesized through a thiol-ene "click" reaction. The PCL networks have various functional properties, including self-healing, shape memory, reprocessability, and degradability. Pronouncedly, a healing efficiency of 92% on the yield strength of the PCL network is obtained after heating for 1 h at 60 °C. Meanwhile, the PCL networks show shape memory property with fixing ratio (R f ) and recovery ratio (R r ) at 98% and 95%, respectively. The PCL network still retains good mechanical properties after reprocessing cycles and can be fast-decomposed through a thiol-disulfide exchange reaction.

Herein, we report a facile synthesis of nano-TiO2@carbon microspheres (TiO2@C) with enhanced photocatalytic performances. The spherical resorcinol–formaldehyde (RF) hydrogels were firstly prepared and then in-situ loaded with TiO2 via a one-pot protocol. The target products were obtained after the composite hydrogels were carbonized at high temperatures. The whole protocol was carried out under atmospheric pressure in no need of special high pressures. The as-prepared TiO2@C is unique, which is characterized by the well-controlled sub-micron morphology, highly crystalline anatase nano-TiO2, and the hierarchically micro–mesoporous structure. The composite spheres could be applied as a new kind of photocatalyst, and the excellent performance was evaluated in the photodegradation of chlorobenzene in water. The enhanced photocatalytic activity of TiO2@C could be explained by the synergistic effect of the RF–C supporting with the anatase nano-TiO2.

The limitation and regulation of formaldehyde emissions (FE) now shows great importance in wood-based materials such as plywood and particle board manufactured for building and furnishing materials. The widely used formaldehyde-based adhesives are one of the main sources of FE from the wood products. In this work, a new kind of long-term effective formaldehyde scavenger in the microcapsule form was prepared by using an intra-liquid desiccation method. The characterizations of the capsule (UC) were performed including the morphologies, the yields, the loading efficiency as well as its sustained-release of urea in aqueous conditions. The prepared UC could be integrated in urea-formaldehyde resins by simply physical blending, and the mixtures were available to be applied as the adhesives for the manufacture of plywood. The bonding strength (BS) and the FE of the bonded plywood in both short (3h) and long (12 week) period were evaluated in detail. It was found that the FE profile of the plywood behaved following a duple exponential law within 12 week. The addition of UC in the adhesive can effectively depress the FE of the plywood not only in a short period after preparation but also in a long-term period during its practical application. The slow released urea would continuously suppress the emission of toxic formaldehyde in a sustained manner without obviously deteriorating on the BS of the adhesives.

A convenient technique is reported to fabricate Ag-SiOx hyperbolic metamaterials (HMMs) as robust surface-enhanced Raman scattering (SERS) substrates based on roll-up nanotechnology. As an illustration, dramatic enhancement is achieved using Rhodamine 6G as a molecular probe, which indicates that a larger plasmonic density of states exist, leading to a greatly enhanced local electromagnetic (EM) field when the sample is irradiated with a laser beam. Optimized results are obtained by controlling the thickness of alumina coating onto Ag-SiOx HMMs using atomic layer deposition. Finite-difference time-domain simulations further illustrate the excitation of localized surface plasmon modes by calculating the EM field properties on the surface of Ag-SiOx HMMs. This efficient method of producing Ag-SiOx HMMs with highly SERS-active properties could spur expanding applications in metamaterials and bioanalysis.

A convenient technique was developed to fabricate gold-capped TiO 2 nanocomposites as robust, cost-efficient and recyclable surface-enhanced Raman scattering (SERS) substrates. The morphologies of obtained nanocomposites exhibit nanotube, nanolace, and nanopore nanostructures by adjusting TiO 2 anodization parameters. As an illustration, dramatic enhancement is achieved using Rhodamine 6G as a molecular probe. Owing to activation by the incident laser beam, the localized electromagnetic field on the nanocomposite surface can be enhanced subsequently amplifying the Raman signal. The topography can be further tuned to optimize the enhancement factor by adjusting the time of gold evaporation. Finite-difference time-domain calculations indicate the nanopore structure may possess excellent SERS characteristic due to the high density of hot spots. In addition, the substrate can be self-cleaned under ultraviolet irradiation due to the superior photocatalytic capacity of the Au–TiO 2 nanocomposites. Our Au–TiO 2 nanocomposites with highly SERS-active properties and recyclability shows promising applications in the detection and treatment of pollutants.

This work reports a facile method to fabricate gold coated copper(II) hydroxide pine-needle-like micro/nanostructures for surface-enhanced Raman scattering (SERS) application. The effects of reaction parameters on the shape, size and surface morphology of the products are systematically investigated. The as-prepared 3D hierarchical structures have the advantage of a large surface area available for the formation of hot spots and the adsorption of target analytes, thus dramatically improving the Raman signals. The finite difference time domain calculations indicate that the pine-needle-like model pattern may demonstrate a high quality SERS property owing to the high density and abundant hot spot characteristic in closely spaced needle-like arms.

This work reports a simple yet highly efficient method to fabricate transparent substrates for surface enhanced Raman scattering (SERS) application. Our technique is based on a fume etching process for commercial ITO-glass (ITO film on glass substrate) with atmospheric fume of hydrochloric acid (HCl). Surface analyses suggested that the spontaneously evaporated HCl molecules chemically reacted with ITO and formed island-like nanostructures. The topography of the ITO surface can be tuned to optimize the SERS efficiency by adjusting the etching parameters. On-line SERS spectra of the R6G solution concentration variation were also obtained to study the adsorption behavior of R6G on ITO surface. This convenient, simple, and low-cost method of making transparent SERS-active substrates potentially opens a way toward rapid, nondestructive and quantitative bioanalysis, particularly in microfluidics.

Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization was utilized to synthesize poly(methacrylic acid)-b-poly(butyl acrylate) (PMAA-b-PBA) amphiphilic block copolymer dispersions in methanol by using the PMAA homopolymer with dithiobenzoate end-group as macro-RAFT agent. And the PMAA macro-RAFT agent was synthesized first by using 4-cyanopentanoic acid dithiobenzoate (CADB) as RAFT agent, where the intermolecular hydrogen bondings can be formed between the MAA units. With the formation of solvophobic PBA block by propagating BA monomer on the PMAA homopolymer chain, the PMAA-b-PBA block copolymer in situ self-assembled into core/shell sphere with PBA and PMAA blocks as core and shell matrix, respectively. The repulsive steric interaction within the PMAA block on shell matrix stabilized the copolymer particles in methanol dispersion, which further resulted in the formation of wrinkly surface pattern on the PMAA-b-PBA copolymer film. During the film formation process, the core/s...

The core–shell polyphenylsilsesquioxane-poly (styrene–butyl acrylate) hybrid latex paticles with polyphenylsilsesquioxane as core and poly (styrene–butyl acrylate) as shell were successfully synthesized by seeded emulsion polymerization using polyphenylsisesquioxane (PPSQ) latex particles as seeds. X-ray diffraction (XRD) indicated that the polyphenylsilsesquioxane (PPSQ) had ladder structure, and PPSQ had incorporated into the hybrid latex particles. Transmission electron microscopy (TEM) confirmed that the resultant hybrid latex particles had the core–shell structure. TEM and dynamic light scattering (DLS) analysis indicated that the polyphenylsisesquioxane latex particles and obtained core–shell hybrid latex particles were uniform and possessed narrow size distributions. X-ray photoelectron spectroscopy (XPS) analysis also indicated that the PPSQ core particles were enwrapped by the polymer shell. In addition, compared with pure poly (styrene–butyl acrylate) latex film, the polyphenylsilsesquioxane-poly (styrene–butyl acrylate) hybrid latex film exhibited lower water uptake, higher pencil hardness and better thermal stability.

Diglycidyl ether of bisphenol A (DGEBA)/fluoro-terminated hyperbranched poly(phenylene oxide) (FHPPO) composites with improved mechanical and dielectric performances were prepared by blending a FHPPO with DGEBA. The low-polarity building blocks, abundant fluorinated terminal groups, and the inherent free volume brought by FHPPO efficiently lowered the dielectric constant and the dissipation factor. The free volumes of the cured DGEBA/FHPPO composites, which were quantified by positron annihilation lifetime spectroscopy, increased with the FHPPO loading. The moisture absorption of composites also decreased after the introduction of FHPPO due to the hydrophobicity of fluorinated substituents. Dynamic mechanical analysis tests and scanning electron morphology revealed that FHPPO phase separated from the composites during the curing process. The average diameter of dispersed FHPPO particles increased proportionally with the FHPPO loading. Composites with dispersed particle size of around 150 nm showed the best comprehensive mechanical performance. In addition, incorporation of FHPPO, which has lots of aromatic structures, into DGEBA also increased the thermal stabilities. POLYM. COMPOS., 34:1051-1060, 2013. (c) 2013 Society of Plastics Engineers

Platinum thin films are deposited on anodic aluminium oxide (AAO) templates by atomic layer deposition (ALD). The highly ordered island-like platinum nanostructures formed on the AAO template produce a high Raman scattering signal because of the periodical hexagonal arrangement. As an illustration, dramatic enhancement is achieved using Rhodamine 6G (R6G) as a molecular probe.Field-emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) show that the gap between the island-like structures is below 10 nm. Owing to activation by the incident laser beam, the localized electromagnetic field on the platinum island surface can be dramatically enhanced by the sub-10 nm regime subsequently amplifying the Raman signal. Finite-difference time-domain (FDTD) calculation matches the experimental phenomena suggesting that the excellent surface-enhanced Raman scattering (SERS) characteristics of the platinum structure arise from the high density and abundance of hot spots. Because the platinum film is inert in air, the SERS enhancing substrate can be used reliably in many trace chemical and biological detection applications.