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Multilayer membranes prepared via microlayer coextrusion have attracted wide attention due to their unique properties and broad applications. In present study, the foam/film alternating multilayer sheets based on ethylene-vinyl acetate copolymer (EVA) and high-density polyethylene are successfully prepared via microlayer coextrusion. The cells in the sheets are single-cell-array along the foamed EVA layers with uniform cell size. In addition, the effects of layer number and foam relative thickness on morphology, mechanical properties, damping and heat insulation properties are investigated. The cell size decreases significantly with increasing layer number due to the enhanced confine effects. The tensile strength, elongation at break, and heat insulation also increase significantly. However, the mechanical damping properties change little in the observed frequency. Meanwhile, with higher relative thickness of EVA foam, the sheets have lower tensile strength and lower thermal conductivity, while the damping properties are enhanced in a specific frequency scope. The elongation at break of the optimized sample comes to 800% and the thermal conductivity decreases to 61 mW·m−1·K−1, which shows high toughness and low thermal conductivity, indicating a possible method for preparing materials with high toughness and heat-insulating properties.

The intramolecular cross-linking of single polymer chains can form single-chain nanoparticles (SCNPs), which have many applications. In this study, styrenic copolymers with pendent triphenylphosphine as the coordination site for platinum ions (Pt(II)) and benzocyclobutene as the latent reactive groups are synthesized. Triphenylphosphine groups in the chains can coordinate Pt(II) and aid slight single-chain folding in dilute solution. The intramolecular cross-linking caused by the ring-open reaction of benzocyclobutene completes the single-chain collapse and forms stable SCNPs in dilute solution. Pt(II) embedded in SCNPs can be further reduced to platinum atoms (Pt(0)). Pt(0) steadily and atomically dispersed in SCNPs exhibits better catalytic properties than normal polymer carried platinum particles do for the reduction of p-nitrophenol to p-aminophenol.

The ring-forming behavior of polymers with an odd number of arms in highly dilute solutions has been studied using tri-arm polystyrene (PSt3) as a model through combining atom transfer radical polymerization (ATRP) and atom transfer radical coupling (ATRC) technologies. The star polymer, PSt3, with three arms and a central core was obtained by ATRP of styrene using a designed initiator with three active Br terminals and ester groups, followed by the Br terminal–Br terminal radical coupling of PSt3, which was implemented via intramolecular ATRC under high dilution conditions. A tadpole-shaped cyclic polymer (tadpole-PSt) was successfully prepared, proving that there no intermolecular side reactions that occur during the intramolecular ATRC of PSt3. Interestingly, the tadpole-PSt not only possesses a cyclic topology, but also contains a living chain, in contrast to other cyclic analogues that have been previously reported. Finally, the tadpole-PSt was used as a building block to construct a type of barbell polymer (barbell-PSt) by removing most of the solvent via vacuum distillation at the end of the intramolecular ATRC of PSt3. Size exclusion chromatography, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, 1H nuclear magnetic resonance spectroscopy and hydrolysis experiments proved that high-purity cyclic polymers (tadpole-PSt and barbell-PSt) were successfully prepared. The thermal properties of the cyclic and star polymers were analyzed using differential scanning calorimetry and thermogravimetric analysis. The results demonstrated that the formation of a cyclic topology makes a huge contribution to the increase in the glass transition temperature (Tg) and thermal stability of the polymer.

In this work, polyvinylpyrrolidone (PVP) coated Ag-rich Ag2Te nanowires (NWs) were synthesized by a wet chemical method using PVP coated Te NWs as templates, and a flexible PVP/Ag/Ag2Te ternary com...

Anion exchange membranes with high ionic conductivity and dimensional stability attract a lot of research interests. In present study, a series of fluorene-containing poly(arylene ether sulfone)s containing imidazolium on the flexible long side-chain are synthesized via copolycondensation, Friedel-Crafts reaction, ketone reduction, and Menshutkin reaction sequentially. The membranes used for characterization and membrane electrode assembly are obtained by solution casting and ion exchange thereafter. The morphology of the membranes is studied via transmission electron microscopy, and the microphase separation is observed. The long side-chain structure is responsible for the distinct hydrophilic-hydrophobic microphase separation, which facilitates the transport of hydroxide ions in the membranes. The incorporation of imidazolium on the flexible long side-chain is favorable for the ionic aggregation and transport in the membranes. The resulted membranes exhibit high hydroxide conductivities in the range of 48.5–83.1 mS cm−1 at 80 °C. All these membranes show good dimensional stability and thermal stability. The single cell performance shows a power density of 102.3 mW cm−2 at 60 °C using membrane electrode assembly based-on one of the synthesized polymers.

A typical multicyclic branched-topology polystyrene (c-BPS) with high molecular weight (30 K ≤ Mw MALLS ≤ 300 K g mol−1) and narrow dispersity (1.2 ≤ Đ ≤ 1.3) was efficiently synthesized by combining atom transfer radical polymerization (ATRP) and atom transfer radical coupling (ATRC) techniques. The topological constraints imposed by the presence of cyclic units and branch points had a marked influence on the entanglement behaviors of the polymer chains in solution. Therefore, c-BPS possesses the lowest loss modulus (G′′) and viscosity (η), the highest diffusion coefficient (D0), the largest mesh size (ξ) and the fastest terminal relaxation (TR), compared with branched and linear precursors.

In recent years, volatile organic compound (VOC) gases have caused potential harm to people's health. This study reveals the preparation of polyethylene porous fiber membrane with excellent low-concentration VOCs filtration performance via laser irradiation technology. A neodymium-doped yttrium aluminum garnet (Nd:YAG) pulsed laser beam was used to scan the laser-sensitive low-density polyethylene/carbon black (LDPE/CB) fibers prepared by nanolayer coextrusion in the air. The controllable thermal energy generated by laser irradiation makes the surface of the fiber membrane to produce a porous carbon layer in situ. Laser power and scanning speed are important parameters for controlling laser-induced carbonization. The results indicate that the rich "fluffy" carbon structures on the surface of the porous fiber membrane can efficiently adsorb xylene gas. This study can provide a positive reference for the large-scale preparation of polyolefin porous fiber membrane with VOCs filtration by simple and efficient laser irradiation method.

In this study, novel shape memory composite of polyolefin elastomer (POE)/lauric acid (LA)/carbon black (CB) nanoparticles with triple-stimuli responsive shape memory effect (SME) is investigated. Crystalline small molecule LA, replacing the commonly used semi-crystalline polymers, is utilized to cooperate with POE and acts as the fixing phase. CB nanoparticles are specifically dispersed in the POE phase, resulting in the formation of intensive conductive pathways and an improvement in the recovery force. The composites can be deformed into arbitrary temporary shapes, and exhibit high shape recovery and fast response to thermo-, electro-, and solvent-stimuli. In our hands, 10 V is capable of triggering shape recovery of the POE/LA/CB (50/50/20) composite, which is undoubtedly safe for a wide range of applications. Excitingly, the electroactive SME of the composites can be conveniently regulated by the CB content and the applied voltage.

This work reports the application of the microwave-assisted solvothermal process to synthesize Pt-Ni alloy polyhedral nanoparticles for oxygen reduction reaction (ORR). Well-faceted nanoparticles, mainly octahedral and tetrahedral ones were generated. All the as-prepared Pt-Ni nanocrystals are uniformly dispersed on the carbon support. HR-TEM images confirm that the polyhedral nanoparticles are exposed by (111) facets. When the number of pulses is 12, rotating disk electrode (RDE) demonstrate ORR activities of the as-prepared catalysts with the highest mass activity of 1.217 A·mgPt−1 and specific activity of 4.41 mA cm−2Pt at 0.9ViR-free, which is over 11 and 25 times than that of Pt/C catalyst, respectively. Even after being prepared into MEA, the catalyst prepared by 12 microwave pulses still possesses higher performance than commercial Pt/C. Thus, this method can greatly shorten the preparation time to expand the scale of production of the high-performance electrocatalyst.

To improve the chemical stability and acid doping levels of proton exchange membranes, a series of sulfonated polybenzimidazole multiblock copolymers containing pyridine rings (sPBI40-b-PyPBI5-b-PIx) was synthesized. All the copolymers exhibited excellent solubility. The proton exchange membranes were prepared using a solvent casting method. All the membranes were characterized by thermal stability, a tension test, chemical stability, dimensional stability, PA-doping ability, and proton conductivity. All of the membranes had good thermal stability, mechanical properties, and dimensional stability. The proton conductivity of sPBI40-b-PyPBI5-b-PI5 (ion exchange capacity, IEC = 1.83 mmol g−1) was 0.018 S cm−1 at 105 °C and 100% relative humidity. The proton conductivity of the sPBI40-b-PyPBI5-b-PI5 membrane with the highest PA uptake (199.8%) reached 0.23 S cm−1 at 180 °C. The high doping level and the proton conductivity were due to the pyridine group which increased the basicity of the copolymer. The chemical stability of the membranes, which was also a consequence of introducing the pyridine group, was better than that of sPBI-b-PI which does not have a pyridine group. This series of block copolymers have a promising application in proton exchange membranes.

The effects of layer thickness on the compatibility between polycarbonate (PC) and polystyrene (PS) and physical properties of PC/PS multilayered film via nanolayer coextrusion are studied. The morphology of multilayered structure is observed using a scanning electron microscope. This multilayered structure may have a negative impact on the transparency, but it can improve the water resistance and heat resistance of film. To characterize the compatibility between PC and PS, differential scanning calorimetry is used to measure the glass transition temperature. The compatibility is found to be improved with the decrease of layer thickness. Therefore, the viscosity of multilayered film is also reduced with the decrease of layer thickness. In addition, the multilayered structure can improve the tensile strength with the increase of layer numbers. Because of the complete and continuous layer structure of PC, the PC/PS multilayered film can retain its mechanical strength at the temperature above Tg of PS.

Poly(ethylene glycol) methyl ether acrylate (PEGMEA) is copolymerized with 2-(ferrocenecarboxylate ethyl) methacrylate (EMA-Fc) and 4-(propoxy urethane ethyl acrylate) azobenzene (EMA-Azob), respectively. The nanoparticles can be obtained via the single-chain folding of these amphiphilic copolymers with hydrophilic poly(ethylene glycol) (PEG) side chains and hydrophobic ferrocene (or azobenzene) pendant groups in dilute aqueous solution via intramolecular hydrophobic interaction. After the addition of cyclodextrin, the inclusion complex can be formed between cyclodextrin and ferrocene (or azobenzene) pendant groups, which makes the amphiphilic copolymers hydrophilic and triggers the chain unfolding of the nanoparticles in aqueous system. Such kind of process has potential application in the fields of drug delivery systems and their controlled release, sensors, controllable catalysis, mimicry of biomacromolecules, as well as other fields.

Polypropylene (PP)/polyethylene (PE) multilayer separators with cellular-like submicron pore structure for lithium-ion battery are efficiently fabricated by the combination of multilayer coextrusion (MC) and thermal induced phase separation (TIPS). The as-prepared separators, referred to as MC-TIPS PP/PE, not only show efficacious thermal shutdown function and wider shutdown temperature window, but also exhibit higher thermal stability than the commercial separator with trilayer construction of PP and PE (Celgard® 2325). The dimensional shrinkage of MC-TIPS PP/PE can be negligible until 160 °C. In addition, compared to the commercial separator, MC-TIPS PP/PE exhibits higher porosity and electrolyte uptake, leading to higher ionic conductivity and better battery performances. The above-mentioned fascinating characteristics with the convenient preparation process make MC-TIPS PP/PE a promising candidate for the application as high performance lithium-ion battery separators.

The agglomeration of powder photocatalysts for water remediation can reduce the catalytic efficiency, and the difficulty to be recycled will cause the secondary pollution. A facile method suitable for volume production of polyvinylidene fluoride (PVDF)-based nanofibers as well as mat with high photocatalytic activity is proposed via nanolayer coextrusion, which is a new top-down method. Hydrophilic TiO2 and acidified multi-walled carbon nanotubes (MWCNTs) are used for the preparation of highly active PVDF photocatalysts. The preparation process is eco-friendly, and no organic solvents are used. The morphology and structure of PVDF/(TiO2/MWCNTs) composite nanofibers are investigated on scanning electron microscope and transmission electron microscope. X-ray diffraction patterns confirm that TiO2 is still anatase on nanofiber surface after melting processing. PVDF/(TiO2/MWCNTs) composite nanofibers exhibit high photocatalytic efficiency for the degradation of methylene blue in water. In photoluminescence and ultraviolet spectra, the red shift phenomenon of the absorption peak of the nanofibers is observed. It is found that MWCNTs can improve the photocatalytic efficiency of TiO2 in PVDF composite nanofibers, in which MWCNTs can be aligned along the naofibers and play a role as the bridge among TiO2 particles and enhance the transfer of electrons. This facile and high efficient method can be widely used for the volume production of various kinds of similar functional nanofibers in the future.

A facile and continuous method to prepare porous polypropylene (PP)/polyethylene (PE) multilayer membranes as separators for lithium-ion batteries via multilayer coextrusion and CaCO3 template method is proposed. Scanning electron microscopy (SEM) images indicate that the membrane exhibits abundant and well-connected sub-micron porous structure. Besides, the physical and electrochemical properties of the membranes, such as thickness, porosity, electrolyte uptake, ionic conductivity, electrochemical stability, thermal stability, and battery performance, are characterized and compared with the commercial separators with trilayer construction of PP and PE (e.g., Celgard® 2325). The results indicate that the multilayer PP/PE separators exhibit higher porosity as well as higher electrolyte uptake and retention than Celgard® 2325, which will definitely increase the ionic conductivity, and consequently improve the battery performances. More importantly, the PP/PE multilayer separators not only show effective thermal shutdown function, but also shows significant advantages of high thermal stability up to 160 °C. The thermal shutdown function of PP/PE multilayer membranes can be adjusted widely in the temperature range from 127 °C to 165 °C, which is wider than that of the commercial separators. The above results combined with the convenient and cost-effective preparation process makes porous PP/PE multilayer membranes a promising alternative to the commercialized trilayer lithium-ion battery separators.

Three novel types of thiophene‐containing oxime sulfonates with a big π‐conjugated system were reported as non‐ionic photoacid generators. The irradiation of the newly synthesized photoacid generators using near UV–visible light‐emitting diodes (LEDs) (365–475 nm) results in the cleavage of two weak NO bonds in single molecules, which lead to the generation of different sulfonic acids in good quantum and chemical yields. The mechanism for the NO bond cleavage for acid generation was supported by the UV–visible spectra and real‐time ¹H NMR spectra. They are developed as high‐performance photoinitiators without any additives for the cationic polymerization of epoxide and vinyl ether upon exposure to near‐UV and visible LEDs (365–475 nm) at low concentration. In the field of photopolymerization, especially visible light polymerization, it has great potential for application. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 776–782

In this study, a novel superhydrophobic and superoleophilic polystyrene/carbon nanotubes foam (PCF) for oil/water separation was fabricated via a facile two-step strategy. The combination of phase inversion and porogen leaching generated hierarchical porous structure with high porosity. Carbon nanotubes (CNTs) were firmly immobilized on the polystyrene (PS) skeleton, constructing a nanoscale-rough surface with superhydrophobicity and superoleophilicity. The PCF displayed large absorption capacity, fast absorption rate, and strong preference for organic liquids, capable of removing oil efficiently from water surface and surfactant stabilized oil-in-water emulsion. The PCF shows great potentials in oil spill treatment and chemical accident remediation. In addition, the raw PS used in PCF fabrication was from recycled packages, providing a feasible path for reducing the environmental pollution and changing waste into valuable resources.

Sulfonated polybenzimidazole-polyimide block copolymers are synthesized through condensation polymerization at high temperature. The length of the polyimide chain is varied to give a series of block copolymers with various block lengths. The as-synthesized block polymers are used to prepare the corresponding membranes through the solvent evaporation method. The structure of the block copolymers is characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Their mechanical strength, thermal behavior, water uptake, swelling ratio, and proton conductivity, as well as oxidative stability are also investigated. All the block copolymers exhibit good thermal stability, dimensional stability, mechanical strength, and proton conductivity. Compared to the random sulfonated polyimide-containing benzimidazole membranes with the same degree of sulfonation, the membranes prepared from the block copolymers show higher proton conductivities. The proton conductivities of the block copolymer membranes range from 6.2 × 10−4 to 1.1 × 10−2 S cm−1 at 105 °C. The block copolymer membrane doped with phosphoric acid exhibits proton conductivity higher than 0.2 S cm−1 at 160 °C, indicating its potential applications in proton exchange membrane fuel cells operated under high temperature and low humidity conditions.

Novel thioxanthone (TX) derivatives are used as versatile photoinitiators upon visible light-emitting diode (LED; e.g., 405, 425, and 450 nm) exposure. The mechanisms for the photochemical generation of reactive species (i.e., cations and free radicals) produced from photoinitiating systems based on the photoinitiator and an iodonium salt, tris(trimethylsilyl)silane, or an amine, were studied by UV–vis spectroscopy, fluorescence, cyclic voltammetry, steady-state photolysis, and electron spin resonance spin-trapping techniques. The reactive species are particularly efficient for cationic, free radical, hybrid, and thiol-ene photopolymerizations upon LED exposure. The optimized photoinitiating systems exhibit higher efficiency than those of reference systems (i.e., isopropyl TX-based photoinitiating systems), especially in the visible range. According to their beneficial features, these photoinitiating systems have considerable potential in photocuring applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

Triple-shape memory polymers (triple-SMPs) have one permanent and two temporary shapes, which enable more complex actuation than traditional dual-SMPs. This work reports a novel polyolefin elastomer (POE)/stearic acid (SA) composite with excellent triple-shape memory and dual-responsive properties. SA displays two well-separated thermal transitions when melt-blending with POE, and is capable of memorizing two temporary shapes under different temperatures. It is found that the robust “house of cards” structure formed by the flake-like SA crystals in the composite is the key player behind the unique behavior. In addition, the actuation of the POE/SA composite can also be triggered upon exposing the material to the appropriate chemical vapor at room temperature. The triple-shape memory and dual-responsive ability atop the simple preparation process dramatically widen the applications of this fantastic material.

The effects of matrix viscosity on alignment of multi-walled carbon nanotubes (MWCNTs) and physical properties of high density polyethylene (HDPE)/MWCNTs composite nanofibers via nanolayer coextrusion are studied. The alignment states are altered depending upon the matrix viscosity of the composite nanofibers. The morphology and nano-sized diameter of the nanofibers are observed on scanning electron microscope. To characterize the prioritized alignment and dispersion of MWCNTs in the matrix, transmission electron microscopy, polarized Raman spectra, and high resolution optical microscopy are used. It is found that the alignment of MWCNTs in higher viscosity matrix of the nanofibers is better than that in lower viscosity. The aligned MWCNTs composite nanofibers have smaller slope variations of rheological curves with increasing content of MWCNTs. In addition, the higher aligned HDPE/MWCNTs composite nanofibers exhibit higher decomposition temperature and enhanced mechanical properties. However, the poorly aligned nanofibers have higher electrical and thermal conductivities due to the easily formed three-dimensional network.

The degradation of membranes in proton exchange fuel cells by chemical oxidation is one of the main factors limiting their lifetime. The effect of electric field on the oxidative degradation of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole] (PBI) was investigated using electro-Fenton tests. The degraded PBI was characterized by measuring the sample's intrinsic viscosity (ηint) and weight loss and using thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance spectroscopy (1H NMR), and X-ray photoelectron spectroscopy (XPS). When the intensity of the electric field was increased from 0 V/m to 5000 V/m, the membrane's weight decreased, while the ηint of PBI decreased rapidly. Meanwhile, a larger number of larger pores formed on the PBI membranes, according to SEM images. The thermal stabilities of the degraded PBI membranes decreased significantly when the intensity of the electric field increased. FTIR, 1H NMR, and XPS spectra revealed that an electric field accelerated the formation of amide and amino groups after the breakdown of benzimidazole rings in PBI. The amino groups were stabilized by protonation in the acidic Fenton reagent. A possible mechanism for the increased oxidative degradation of PBI in an electric field was proposed.

A method for large-scale processing of low density polyethylene (LDPE) nanofibers reinforced by aligned multi-walled carbon nanotubes (MWCNTs) is achieved via nanolayer coextrusion. The morphology and nano-sized diameter of the nanofibers are observed on scanning electron microscope. The prioritized alignment and dispersion of MWCNTs along the fiber axis are determined by transmission electron microscopy, polarized Raman spectra, and high resolution optical microscopy. The dispersion of MWCNTs in nanofibers is better than that in homologous micron-fibers. In addition, MWCNTs can promote the crystallization of LDPE in varying degrees which depend on the fiber diameter and MWCNTs content. As a result of the alignment of MWCNTs, the nanofibers exhibit enhanced mechanical properties. The tensile strength of LDPE(1 wt% MWCNTs) nanofibers is more than twice of pure nanofibers (without MWCNTs). The volume resistivity of the LDPE(MWCNTs) nanofiber mats containing 9 wt% MWCNTs can be reduced to 100 Ω cm.

International audience; The effect of surface chemical heterogeneity and hydrodynamics on particle transport and deposition in porous media was investigated by microscale simulations using a colloidal particle tracking model, called 3D-PTPO (Three-dimensional particle tracking model by Python® and OpenFOAM®) code. This work is aimed as a step toward modeling of transport and deposition in porous media idealized as a bundle of straight capillary tubes. Therefore, our focus is put upon a three-dimensional capillary with periodically repeating chemically heterogeneous surfaces namely crosswise strips patterned and chess board patterned. The main feature of this recent model is to renew the flow field by reconstructing the pore structure, to take the pore surface modification induced by the volume of the deposited particles into account. The dependency of the deposition probability and the dimensionless surface coverage (Γ/ΓRSA) on the frequency of the pitches (λ), the Péclet number (Pe) and the favorable area fraction (θ), as well as the distribution of the spatial density of deposited particles along the capillary tube were studied. The results indicate that particles tend to deposit at the leading and trailing edges of the favorable strips, and the deposition is more uniform along the patterned capillary compared to the homogeneous one. In addition, for the chemically heterogeneous capillary, in a similar manner as for the homogeneous one, a definite plateau exists for the Γ/ΓRSA at low Péclet values. For high Pe values, the declining trend for Γ/ΓRSA versus Pe is in good agreement with the derived power law dependence already observed in the literature for fully adsorbing surfaces. Moreover, for fixed θ the deposition probability is linearly correlated with λ and for given λ, such a deposition probability is also a linear function of θ.

In this work, polyvinylpyrrolidone (PVP) coated Ag-rich Ag

The microlayer or nanolayer coextrusion of hundreds or thousands of alternating low density polyethylene (LDPE)/polystyrene (PS) microlayers or nanolayers were used to study the orientation of LDPE crystals in the confined quasi-two-dimensional or two-dimensional space. The clear and continuous layer structures from microscale to nanoscale can be found in SEM images. The morphology evolution of LDPE crystals in the confined microlayer or nanolayer can be varied from 3D spherulites, 2D spherulites, stacked edge-on lamellar, to single edge-on lamellar. Due to the orientation of the LDPE crystals, the tensile strength of the films increases obviously when the layer thickness reduces to nanoscale. The 2D small angle X-ray scattering (SAXS) patterns can reflect the average degree of orientation of LDPE in the confined layers. The stacking of LDPE lamellae is suppressed in interlamination and oppositely in parallel to the extrusion direction. The specific orientation function f can be calculated from the patterns. The infrared dichroism further confirms the mutation of the orientation of LDPE crystals from microscale to nanoscale in the confined space.

A simple and efficient technique was developed to generate continuous polymer nanofibers by combining multilayer co-extrusion with a unique exit cutting die. This is an environment-friendly approach and is capable of converting multilayered films to fibers through a simple physical cutting process. Poly(lactic acid) (PLA) fibers with down to 50 nm width were successfully produced using this new technique. Interestingly, the obtained PLA nanofibers had single crystal structure, which previously formed only in dilute solutions. This new approach creates a highly efficient, versatile, and economic pathway for large-scale fabrication of polymer nanofibers. In principle, it is applicable to any melt-processable polymer, and the obtained nanofibers can be used in wide areas such as transparent nanosheets, membranes, filters, tissue scaffolds, etc.

An efficient strategy for comprehensive utilization of the conjugated sulfonium salt photoacid generator (PAG), namely, 3-{4-[4-(4-N,N′-diphenylamino)-styryl]phenyl}phenyl dimethyl sulfonium hexafluoroantimonate, was developed through photoinitiated cationic photopolymerization (CP) of epoxides and vinyl ether upon exposure to near-UV and visible light-emitting diodes (LEDs; e.g., 365, 385, 405, and 425 nm). Photochemical mechanisms were investigated by UV–vis spectra, molecular orbital calculations, fluorescence, cyclic voltammetry, and electron spin resonance spin-trapping analyses. Compared with commercial PAGs, the prepared conjugated sulfonium salt generated H+, which can be used as photoinitiator. Moreover, the fluorescent byproducts from photodecomposition can be used as photosensitizer of commercial iodonium salt in the photoinitiating systems of CP. These novel D-π-A type sulfonium-based photoinitiating systems are efficient (epoxide conversion = 85–90% and vinyl conversion >90%; LEDs upon exposure to 365–425 nm) even in low-concentration initiators (1%, w/w) and low curing light intensities (10–40 mW cm−2). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2722–2730

A feasible method to prepare single-chain polymer nanoparticles (SCNPs) loading metal catalysts via intramolecular collapse of the linear polymers is proposed. Styrene sulfonyl azide/acrylonitrile copolymers are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Acrylonitrile moieties in the copolymers can adsorb cupric ions and form SCNPs via the thermal decomposition of pendant sulfonyl azide and subsequent intramolecular cross-linking. Then L(+)-ascorbic acid sodium salt is used to reduce these cupric ions into cuprous nanoparticles in SCNPs. The mean diameter of composite SCNPs is in the range of 10–30 nm, in which cuprous moieties (diameter 5–10 nm) are implanted. The size of SCNPs has significant influences on the diameter of loaded cuprous moieties. It is indicated that these single-chain polymer nanoparticles carried cuprous exhibit better catalytic properties for the click reaction of alkyne and azide.

To meet highly conductive and chemical stable anion exchange membranes (AEMs), a series of multi-block poly(ether sulfone)s with long side chains densely terminated by piperidinium (bPES-Pip-X-Y) are synthesized. The multi-block structure and the aggregation of ionic groups on the flexible side chains are responsible for the distinct hydrophilic/hydrophobic microphase separation, which can be observed via transmission electron microscopy (TEM). The resulted membranes achieve the high conductivity (in-plane) of 48.5–105.4 mS cm−1 at 80 °C. Moreover, the AEMs prepared exhibit good alkaline stability due to the presence of cation-terminated long side chain structure. The bPES-Pip-10-5 membrane still maintains 88% of the original conductivity after treated in 1 M KOH solution at 60 °C for 336 h. The membrane electrode assembly based on bPES-Pip-10-5 with a power density of 136.9 mW cm−2 at a current density of 292.5 mA cm−2 is obtained.

A new monomer, propargyl-1-methylimidazolium bromide, is synthesized. A series of poly(ether sulfone)s with pendent imidazolium (PES-Im-x) are synthesized from poly(ether sulfone)s with azide via nucleophilic polycondensation, bromination, and azidation, which are then reacted with propargyl-1-methylimidazolium bromide via click chemistry. The membranes are prepared sequentially via solution casting and ion exchange, which exhibit good alkaline stability under basic and elevated temperature conditions. The micro-phase separation of the membranes is observed on transmission electron microscopy. The conductivities of the membranes achieve in the range of 3.53 × 10−2 to 5.76 × 10−2 S cm−1 at 80 °C, which are related to the introduction of dense imidazolium groups on the side chains of the polymers. The designed structure facilitates the aggregation and transport of the ions in the membranes. The membrane electrode assembly based on PES-Im-38 with a power density of 18.0 mW cm−2 at 60 °C is obtained. In addition, all these membranes show good dimensional stability and thermal stability. It is demonstrated that click reaction may provide a viable strategy for the further preparation of high performance anion exchange membranes.

Single-chain nanoparticles can be obtained via single-chain folding assisted by intramolecular crosslinking reversibly or irreversibly. Single-chain folding is also an efficient route to simulate biomacromolecules. In present study, poly(N-hydroxyethylacrylamide-co-4'-(propoxy urethane ethyl acrylate)-2,2':6',2''-terpyridine) (P(HEAm-co-EMA-Tpy)) is synthesized via reversible addition fragmentation chain transfer polymerization. Single-chain folding and intramolecular crosslinking of P(HEAm-co-EMA-Tpy) are achieved via metal coordination chemistry. The intramolecular interaction is characterized on ultraviolet/visible spectrophotometer (UV-vis spectroscopy), proton nuclear magnetic resonance ((1)H NMR), and differential scanning calorimetry (DSC). The supramolecular crosslinking mediated by Fe(2+) plays an important role in the intramolecular collapsing of the single-chain and the formation of the nanoparticles. The size and morphology of the nanoparticles can be controlled reversibly via metal coordination chemistry, which can be characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), and atomic force microscope (AFM).

Nanoclay attapulgite (ATP) was first activated with hydrochloric acid to enhance the surface reactivity, and was then allowed to react with a synthetic aromatic tertiary amine coupling agent to introduce electron-donor groups. Subsequently, the surface-initiated reversible addition–fragmentation chain transfer (SI-RAFT) polymerization of methyl methacrylate (MMA) was carried out in the presence of a free RAFT agent cyanoisopropyl dithiobenzoate (CPDB) initiated by a redox pair made up of benzoyl peroxide (BPO) and aromatic tertiary amine functionalized ATP (ATP-ATA). The grafting process was verified by 1H nuclear magnetic resonance, UV-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, thermo gravimetric analysis, transmission electron microscopy and gel permeation chromatography. Kinetic behavior indicated that polymerization using this redox initiation system displayed a living/controlled nature. Both the grafted and free polymers were grown in a controlled manner, and the RAFT polymerization proceeded with 37.6% monomer conversion achieved within 10 h at 50 °C, yielding about 47.4% grafting ratio of polymer relative to hybrid particles with high affinity to organic media.

The surface grafting of attapulgite (ATP) with polystyrene (PS) was established via a simultaneous reverse and normal initiation atom transfer radical polymerization (SR&NIATRP). 4-(chloromethyl)phenyltrimethoxysilane (CMPTMS) chemical bounded on the surface of ATP (ATP-Cl, Cl-I) was prepared via one-step self-assembly. SR&NI ATRP of styrene was conducted using CuCl2 complex tris(2-(dimethylamino)ethyl)amine (Me6-TREN) as the catalytic system, initiated by 2,2-azobis(isobutyronitrile) (AIBN) and ATP-Cl. FT-IR, XRD, XPS, TGA and TEM data were consistent with the grafting of benzyl chloride groups and PS chains on ATP surface. The controllability of polymerization was investigated by the kinetics behavior under different molar ratio of AIBN and CuCl2. The obtained polymer possessed a uniform distribution of molecular weights with a lower polydispersity index of 1.2∼1.4. The relationship between polymerization on the surface of ATP and in solution was discussed in detail based on TGA data of hybrid particles and GPC trace of free polymer in solution. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015

Silica-supported branched polyethylenimine (Sil@PEI) is a conventional adsorbent and shows a limited affinity to anionic surfactants and small dyes (K = 106–107 L/mol). If the PEI is alkylated with cetyl groups (C16), the K of the resulting adsorbents (Sil@PEI@C16-x, where x is the fraction of PEI units being alkylated) is significantly improved. Optimization shows that Sil@PEI@C16-0.15 can best reduce aqueous surfactants to a residue around 10−10 mol/L; while Sil@PEI@C16-0.6 can reduce even small aqueous dyes to a residue below 10−10 mol/L, nearly 105-fold lower than that by Sil@PEI. The adsorbents are well recyclable. It is believed that in the case of dyes, the dense cetyl shell can isolate the PEI from the bulky water and thus suppress the competitive binding by water; while in the case of surfactants, the semiclosed cetyl shell can simultaneously meet electrostatic complement and hydrophobic complement to the surfactants.

Electrochemical oxidation of acetone, 2-propanol, and 1-propanol on Pt was studied by slow scan rate voltammetry at 170 °C using fuel cell with the membrane of the H3PO4 doped polybenzimidazole. Reaction rate orders with respect to partial pressures of the aliphatic compounds and water vapors were determined at E = 0.5 V and at E = 0.9 V, which correspond to low and high surface oxide coverages on Pt. At E = 0.5 V close to zero reaction rate orders in respect to vapor pressures of aliphatic reactants were found. At E = 0.5 V reaction, rate orders with respect to water vapor pressure were slightly higher than unity in all cases. At E = 0.9 V oxidation, reaction rate orders with respect to aliphatic reactant vapor pressure ranged within 0.6–1. Close to zero reaction rate orders with respect to water vapor pressure were found in all cases at E = 0.9 V.

Single-chain folding via intramolecular noncovalent interaction is regarded as a facile mimicry of biomacromolecules. Single-chain folding and intramolecular crosslinking is also an effective method to prepare polymer nanoparticles. In this study, poly(methyl methacrylate-co−2-ureido-5-deazapterines functionalized ethylene methacrylate) (P(MMA-co-EMA-DeAP)) is synthesized via free radical polymerization. The single-chain folding of P(MMA-co-EMA-DeAP) and the formation of the nanoparticles in diluted solution (concentration

Sulfonated polyimides containing benzimidazole (SPIBI) with varies sulfonation degree (DS) are synthesized by 1, 4, 5, 8-naphthalenetetracarboxylic dianhydride (NTDA), 5-amino-2-(4-aminophenyl) benzimidazole (APABI) and 4, 4′-diaminodiphenyl ether-2, 2′-disulfonic acid (ODADS). The cross-linked SPIBI membranes can be prepared with 3, 3′, 5, 5′-tetramethyl-diphenyl diglycidyl ether (TMBP) as cross-linker during the following thermal treatment process. By adjusting the DS of SPIBI and the weight ratio of the crosslinker, a series of the cross-linked membranes are obtained. All the obtained membranes exhibit good cross-linking densities for the gel fractions higher than 75%. Compared to pure SPIBI membranes, the mechanical properties, oxidative and hydrolytic stabilities of the cross-linked membranes are improved significantly. For instance, the tensile strength of the cross-linked membranes is in the range of 53.6–108.4 MPa, the anti-free oxidative stability of SPIBI-80-15 (with a cross-linker content of 15 wt% and DS of 80%) is almost four times of the data of the uncross-linked SPIBI-80 which is tested by Fenton′s reagent (3% H2O2, 3 ppm Fe2+) at 80 °C. SPIBI-80-15 also exhibits much higher hydrolytic stability for more than 1440 h, while that of SPIBI-80 is 27 h in the same condition. The proton conductivity of the cross-linked membranes ranges from 10−3 to 10−2 S cm−1.

Researchers have developed many types of nanoscale materials with different properties. Among them, nanofibers have recently attracted increasing interest and attention due to their functional versatility and potential applications in diverse industries, including tapes, filtration, energy generation, and biomedical technologies. Nanolayer coextrusion, a novel polymer melt fiber processing technology, has gradually received attention due to its environmental friendliness, efficiency, simplicity and ability to be mass-produced. Compared with conventional techniques, nanolayer coextruded non-woven nanofibrous mats offer advantages such as a tunable fiber diameter, high porosity, high surface area to volume ratio, and the potential to manufacture composite nanofibers with different components to achieve desired structures and properties. Dozens of thermoplastic polymers have been coextruded for various applications, and the variety of polymers has gradually continued to increase. This review presents an overview of the nanolayer coextrusion technique and its promising advantages and potential applications. We discuss nanolayer coextrusion theory and the parameters (polymer and processing) that significantly affect the fiber morphology and properties. We focus on varied applications of nanolayer coextruded fibers in different fields and conclude by describing the future potential of this novel technology.

The microscale simulation of colloidal particle transport and deposition in porous media was achieved with a novel colloidal particle tracking model, called 3D-PTPO (Three-Dimensional Particle Tracking model by Python® and OpenFOAM®), using a Lagrangian method. Simulations were performed by considering the elementary pore structure as a capillary tube with converging/diverging geometries (tapered pipe and venturi tube). The particles are considered as a mass point during transport in the flow and their volume is reconstructed when they are deposited. The main feature of this novel model is to renew the flow field by reconstructing the pore structure by taking the volume of the deposited particles into account. The influence of the particle Peclet number (Pe) and the pore shape on the particle deposition therein is investigated. The results are analyzed in terms of deposition probability and dimensionless surface coverage as a function of the number of injected particles for a vast range of Peclet numbers thus allowing distinguishing the behavior in diffusion dominant and advection dominant regimes. Finally, the maximum dimensionless surface coverage Γfinal/ΓRSA is studied as a function of Pe. The declining trend observed for high Pe is in good agreement with experimental and simulation results found in the literature.

Few adsorbents with a macroscopic size can combine well with a 3D microscopically well-tailored surface. Herein, we show that a dendritic amphiphile can directly lead to such an adsorbent, which can simultaneously eliminate anionic dyes, anionic surfactants and hydrophobic polycyclic aromatic hydrocarbons (PAHs) from water.

A new series of organic–inorganic hybrid proton exchange membranes (PEMs) were prepared using sulfonated polyimides containing benzimidazole (SPIBIs) and glycidyl ether of polyhedral oligomeric silsesquioxanes (G-POSS). SPIBIs were synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 5-amino-2-(4-aminophenyl) benzimidazole (APBIA) and 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODADS). The organic–inorganic cross-linked membranes can be prepared by SPIBIs with G-POSS by a thermal treatment process. The cross-linking density of the membranes was evaluated by gel fractions. The water uptake, swelling ratio, mechanical property, thermal behavior, proton conductivity, oxidative and hydrolytic stability of the cross-linked organic–inorganic membranes were intensively investigated. All the cross-linked membranes exhibit high cross-linking density for the gel fraction higher than 70%. Compared to pristine membranes (SPIBIs) and membranes without benzimidazole groups (SPI), the anti-free-radical oxidative and hydrolytic stabilities of cross-linked membranes are significantly higher. The anti-free-oxidative stability of SPIBI-100-P (cross-linked SPIBI membrane with 100% degree of sulfonation) is nearly four-fold higher than that of SPIBI-100. The proton conductivity of the cross-linked membranes ranges from 10−3 S cm−1 to 10−2 S cm−1 depending both on the degree of sulfonation (DS) of the SPIBI and temperature.

Styrenic copolymers with fluorescent anthracene and crosslinkable groups are prepared from styrene (St)/methyl methacrylate (MMA)/1-(azidomethyl)-4-vinylbenzene copolymers (PS-N3), 9-((prop-2-ynyloxy)methyl) anthracene, and 3-(4-ethoxyphenyl)-3,4-dihydro-2H-benzo[e] [1] , [3] oxazine via click chemistry. The fluorescence-labeled nanoparticles are thus prepared via single-chain folding and intramolecular crosslinking in the ultradiluted solution of the polymers with anthracene and benzoxazine functionalities. MMA in the nanoparticles are then hydrolyzed into methacrylic acid, and the nanoparticles become partially hydrophilic. The dimension of the nanoparticles can be controlled in 5–20 nm. Such kind of nanoparticles exhibits excellent fluorescence performance at 412 nm when irradiated under the light of 367 nm.

Fluorine-containing polyimide (FPI) with hydroxyl groups is synthesized from 4,4′-(hexafluoro isopropylidene) diphthalic anhydride (6FDA), 2,2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FAP), and 4,4′-diaminodiphenyl ether (ODA) via high temperature polycondensation. Thereafter, alkynyl groups are introduced into FPI. During the preparation of the composite membrane, alkynyl groups on FPI react with azido methyl of 4,4′-bis(azido methyl) biphenyl via click chemistry and form semi-interpenetrating polymer network (semi-IPN) structure within the composite membranes. The mechanical properties, thermal behavior, water uptake, swelling ratio, proton conductivity, oxidative stability, as well as the performance in single cell operation are investigated. Compared to pure perfluorosulfonic acid (PFSA) polymer membrane, the composite membranes based on semi-IPN of FPI and PFSA exhibit improved mechanical properties, excellent thermal and dimensional stabilities, and suitable proton conductivity. The tensile strength of the composite membranes ranges from 28.0 to 67.0 MPa. With increasing FPI content in the membranes, the dimensional stability of the composite membranes increases. The composite membranes have the proton conductivity from 4.3 × 10 −2 S·cm −1 to 1.0 × 10 −1 S·cm −1 at 100 °C and also have good performances as proton exchange membrane (PEM) in single cell at 80 °C.

O-alkylation of highly polar polyglycerol with alkyl bromides, promoted just by sodium hydroxide in dimethyl sulfoxide (DMSO), is reported. Zimmermann–Dathe type Williamson etherification, which can be carried out by a mild base in DMSO, is very useful in preparing ethers. However, it is always limited to alkyl chlorides or methyl halides due to the elimination reaction. In this contribution, this reaction is promoted to alkyl bromides and iodides just by decreasing the reaction temperature and then it is further applied in preparing a series of O-alkylated hyperbranched polyglycerol (PG). It is found per-alkylation of PG is possible regardless of its dense hydroxyl groups. In addition, the modified method shows selectivity over the halogen species. The resulting core–shell amphiphilic macromolecules (CAMs) can be used for dye encapsulation and they show core-dependent selection over the dye species. For example, the ether-based CAM 1b (PG–O–(C16) 0.61 , 61% of OH groups are O-alkylated by cetyls) is with limited difference from the ester-based CAM 2a ( PG–COO–(C16) 0.60 ), but they show very different guest selection. Controlled release is also available by core design of the CAMs.

Charge-selective separation and recovery of organic ionic dyes by polymeric micelles (PMs) are reported. Branched polyethylenimine (PEI) functionalized with 4-cetyloxybenzaldehyde (CBA) via Schiff-base bonds (PEI@CBA) can extract an anionic dye from cationic contaminants, and transfer it from an aqueous phase into an apolar oil phase, and thus leading to separation. While a physical micelle of PAA@PS, with polyacrylic acid (PAA) as core and polystyrene (PS) as shell, can selectively extract a cationic dye from anionic contaminants. When polar, yet nonionic groups are eliminated from the core of a PM, charge selectivity can be significantly enhanced. Although many anionic–cationic dyes can form a poorly water-soluble complex or precipitate, separation is still feasible with a reasonably designed PM. Finally, entrapment of a guest by a PM is found easy but release may be difficult; in this case, PEI@CBA with an acid-sheddable shell, can recover the entrapped guest. It is also found the encapsulation of a dye is usually accompanied with dye stacking, resulting in a changed UV/vis spectrum. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 872–881