Dual‐Layer Superamphiphobic/Superhydrophobic‐Oleophilic Nanofibrous Membranes with Unidirectional Oil‐Transport Ability and Strengthened Oil–Water Separation Performance

Thin porous membranes with unidirectional oil‐transport capacity offer great opportunities for intelligent manipulation of oil fluids and development of advanced membrane technologies. However, directional oil‐transport membranes and their unique membrane properties have seldom been reported in research literature. Here, it is proven that a dual‐layer nanofibrous membrane comprising a layer of superamphiphobic nanofibers and a layer of superhydrophobic oleophilic nanofibers has an unexpected directional oil‐transport ability, but is highly superhydrophobic to liquid water. This novel fibrous membrane is prepared by a layered electrospinning technique using poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP), PVDP‐HFP containing well‐dispersed FD‐POSS (fluorinated decyl polyhedral oligomeric silsesquioxanes), and FAS (fluorinated alkyl silane) as materials. The directional oil‐transport is selective only to oil fluids with a surface tension in the range of 23.8–34.0 mN m^–1. By using a mixture of diesel and water, it is further proven that this dual‐layer nanofibrous membrane has a higher diesel–water separation ability than the single‐layer nanofiber membranes. This novel nanofibrous membrane and the incredible oil‐transport ability may lead to the development of intelligent membrane materials and advanced oil–water separation technologies for diverse applications in daily life and industry.     

Natural rubber/epoxidised natural rubber-25 blends: morphology, transport phenomena and mechanical properties

Blends of natural rubber (NR)/epoxidised natural rubber (ENR) were prepared and their morphology, transport behaviour and mechanical properties have been studied. Ebonite method was used to study the blend morphology. Transport behaviour of pentane, hexane, heptane and octane was studied in the temperature range 27–60 °C. Different transport parameters such as rate constant, diffusion and permeation coefficients, and sorption coefficient have been calculated. Temperature dependence of diffusion has been used to estimate the activation parameters. The improved performance of NR/ENR blends has been established from the mechanical studies of unswollen, swollen and deswollen samples.     

3D Porous Hydrogel/Conducting Polymer Heterogeneous Membranes with Electro‐/pH‐Modulated Ionic Rectification

Heterogeneous membranes composed of asymmetric structures or compositions have enormous potential in sensors, molecular sieves, and energy devices due to their unique ion transport properties such as ionic current rectification and ion selectivity. So far, heterogeneous membranes with 1D nanopores have been extensively studied. However, asymmetric structures with 3D micro‐/nanoscale pore networks have never been investigated. Here, a simple and versatile approach to low‐costly fabricate hydrogel/conducting polymer asymmetric heterogeneous membranes with electro‐/pH‐responsive 3D micro‐/nanoscale ion channels is introduced. Due to the asymmetric heterojunctions between positively charged nanoporous polypyrrole (PPy) and negatively charged microscale porous hydrogel poly (acrylamide‐co‐acrylic acid) (P(AAm‐co‐AA)), the membrane can rectify ion transmembrane transport in response to both electro‐ and pH‐stimuli. Numerical simulations based on coupled Poisson and Nernst–Plank equations are carried out to explain the ionic rectification mechanisms for the membranes. The membranes are not dependent on elaborately fabricated 1D ion channel substrates and hence can be facilely prepared in a low‐cost and large‐area way. The hybridization of hydrogel and conducting polymer offers a novel strategy for constructing low‐cost, large‐area and multifunctional membranes, expanding the tunable ionic rectification properties into macroscopic membranes with micro‐/nanoscale pores, which would stimulate practical applications of the membranes.     

Effect of Cloisite® 30B on the Diffusion of Irganox 1076 in HDPE

The diffusion of a thermal stabilizer, Irganox 1076, is studied both in pure high‐density polyethylene (HDPE) and HDPE matrix filled with 1 wt% of Cloisite® 30B. The diffusion experiments are carried out by using the Roe method formed by a stack of several polymer films of 120 ± 01 μm in thickness. In this study, a simple method is used to measure the diffusion coefficient, with the aid of Fourier Transform InfraRed spectroscopy without any extraction or refining steps in the analysis. The diffusion coefficient (D_p) of both materials are obtained in the temperature range 80–100°C using the second Fick's law. By applying the Arrhenius equation to the calculated D_p coefficients, an estimation of activation energies of the diffusion process is also achieved. The results indicate that the diffusion coefficient of Irganox 1076 in HDPE has been decreased by adding 1% of Cloisite® 30B.     

Wide‐Range Tunable Dynamic Property of Carbon‐Nanotube‐Based Fibers

A carbon nanotube (CNT) fiber is formed by assembling millions of individual tubes. The assembly feature provides the fiber with rich interface structures and thus various ways of energy dissipation, as reflected by the nonzero loss tangent (>0.028–0.045) at low vibration frequencies. A fiber containing entangled CNTs possesses higher loss tangents than a fiber spun from aligned CNTs. Liquid densification and polymer infiltration, the two common ways to increase the interfacial friction and thus the fiber's tensile strength and modulus, are found to efficiently reduce the damping coefficient. This is because the sliding tendency between CNT bundles can also be well suppressed by a high packing density and the formation of covalent polymer cross‐links within the fiber. The CNT/bismaleimide composite fiber exhibits the smallest loss tangent, nearly the same as that of carbon fibers. At a higher level of the assembly structure, namely a multi‐ply CNT yarn, the interfiber friction and sliding tendency obviously influence the yarn's damping performance, and the loss tangent can be tuned within a wide range, similar to carbon fibers, nylon yarns, or cotton yarns. The wide‐range tunable dynamic properties allow new applications ranging from high quality factor materials to dissipative systems.     

Sorption and diffusion of chlorinated aliphatic hydrocarbon penetrants into diol chain extended polyurethane membranes

Sorption and diffusion of a number of chlorinated alkanes through a diol chain extended polyurethane (PU) membranes have been investigated at 25, 40 and 60 degrees C, based on an immersion weight gain method. From the sorption result, the diffusion (D) and permeation (P) coefficients of halogenated hydrocarbon penetrants have been calculated. Molecular transport data depends on membrane-solvent interactions, size of the penetrants, temperature and also morphology of the chain extended PUs. The temperature dependence of the transport coefficient has been used to estimate the activation parameters for the process of diffusion (E(D)) and permeation (E(P)) from the Arrhenius plots. Furthermore, the sorption results have been interpreted interms of the thermodynamic parameters such as enthalpy and entropy.     

Smart Microcapsules with Molecular Polarity‐ and Temperature‐Dependent Permeability

Microcapsules with molecule‐selective permeation are appealing as microreactors, capsule‐type sensors, drug and cell carriers, and artificial cells. To accomplish molecular size‐ and charge‐selective permeation, regular size of pores and surface charges have been formed in the membranes. However, it remains an important challenge to provide advanced regulation of transmembrane transport. Here, smart microcapsules are designed that provide molecular polarity‐ and temperature‐dependent permeability. With capillary microfluidic devices, water‐in‐oil‐in‐water (W/O/W) double‐emulsion drops are prepared, which serve as templates to produce microcapsules. The oil shell is composed of two monomers and dodecanol, which turns to a polymeric framework whose continuous voids are filled with dodecanol upon photopolymerization. One of the monomers provides mechanical stability of the framework, whereas the other serves as a compatibilizer between growing polymer and dodecanol, preventing macrophase separation. Above melting point of dodecanol, molecules that are soluble in the molten dodecanol are selectively allowed to diffuse across the shell, where the rate of transmembrane transport is strongly influenced by partition coefficient. The rate is drastically lowered for temperatures below the melting point. This molecular polarity‐ and temperature‐dependent permeability renders the microcapsules potentially useful as drug carriers for triggered release and contamination‐free microreactors and microsensors.     

Insight into the flow‐condition‐based interpolation finite element approach: solution of steady‐state advection–diffusion problems

The flow‐condition‐based interpolation (FCBI) finite element approach is studied in the solution of advection–diffusion problems. Two FCBI procedures are developed and tested with the original FCBI method: in the first scheme, a general solution of the advection–diffusion equation is embedded into the interpolation, and in the second scheme, the link‐cutting bubbles approach is used in the interpolation. In both procedures, as in the original FCBI method, no artificial parameters are included to reach stability for high Péclet number flows. The procedures have been implemented for two‐dimensional analysis and the results of some test problems are presented. These results indicate good stability and accuracy characteristics and the potential of the FCBI solution approach. Copyright © 2005 John Wiley & Sons, Ltd.     

High temperature creep measurements in equiatomic Ni‐Ti shape memory alloy

High temperatures creep rates in equiatomic NiTi alloys at three different stress levels and at different temperatures have been measured. It was obtained that the creep rate can be well described by the Dorn equation with n=3. The activation energy of the effective diffusion coefficient, D_c (characterizing the Herring‐Nabarro bulk creep) is Q_c= 226 kJmole^‐1. From comparison of this value with the activation energy of Ni tracer diffusion (155 kJmol^‐1) it was concluded that the Ti is the slower component with high diffusion activation energy close to Q_c.     

Flexible Metal–Organic Framework‐Based Mixed‐Matrix Membranes: A New Platform for H2S Sensors

Metal–organic framework (MOF)–polymer mixed‐matrix membranes (MMMs) have shown great potential and superior performance in gas separations. However, their sensing application has not been fully established yet. Herein, a rare example of using flexible MOF‐based MMMs as a fluorescent turn‐on sensor for the detection of hydrogen sulfide (H₂S) is reported. These MOF‐based MMMs are readily prepared by mixing a highly stable aluminum‐based nano‐MOF (Al‐MIL‐53‐NO₂) into poly(vinylidene fluoride) with high loadings up to 70%. Unlike the intrinsic fragility and poor processability of pure‐MOF membranes, these MMMs exhibit desirable flexibility and processability that are more suitable for practical sensing applications. The uniform distribution of Al‐MIL‐53‐NO₂ particles combined with the permanent pores of MOFs enable these MMMs to show good water permeation flux and consequently have a full contact between the analyte and MOFs. The developed MMM sensor (70% MOF loading) thus shows a highly remarkable detection selectivity and sensitivity for H₂S with an exceptionally low detection limit around 92.31 × 10^?9m , three orders of magnitude lower than the reported powder‐form MOFs. This work demonstrates that it is feasible to develop flexible luminescent MOF‐based MMMs as a novel platform for chemical sensing applications.     

Constructing Connected Paths between UiO‐66 and PIM‐1 to Improve Membrane CO2 Separation with Crystal‐Like Gas Selectivity

Most metal–organic‐framework‐ (MOF‐) based hybrid membranes face the challenge of low gas permeability in CO₂ separation. This study presents a new strategy of interweaving UiO‐66 and PIM‐1 to build freeways in UiO‐66‐CN@sPIM‐1 membranes for fast CO₂ transport. In this strategy, sPIM‐1 is rigidified via thermal treatment to make polymer voids permanent, and concurrently polymer chains are mutually linked onto UiO‐66‐CN crystals to minimize interfacial defects. The pore chemistry of UiO‐66‐CN is kept intact in hybrid membranes, allowing full utilization of MOF pores and selective adsorption for CO₂. Separation results show that UiO‐66‐CN@sPIM‐1 membranes possess exceptionally high CO₂ permeability (15433.4–22665 Barrer), approaching to that of UiO‐66‐NH₂ crystal (65–75% of crystal‐derived permeability). Additionally, the CO₂/N₂ permeation selectivity for a representative membrane (23.9–28.6) moves toward that of single crystal (24.6–29.6). The unique structure and superior CO₂/N₂ separation performance make UiO‐66‐CN@sPIM‐1 membranes promising in practical CO₂ separations.     

Reduced‐order modeling of parameterized PDEs using time–space‐parameter principal component analysis

This paper presents a methodology for constructing low‐order surrogate models of finite element/finite volume discrete solutions of parameterized steady‐state partial differential equations. The construction of proper orthogonal decomposition modes in both physical space and parameter space allows us to represent high‐dimensional discrete solutions using only a few coefficients. An incremental greedy approach is developed for efficiently tackling problems with high‐dimensional parameter spaces. For numerical experiments and validation, several non‐linear steady‐state convection–diffusion–reaction problems are considered: first in one spatial dimension with two parameters, and then in two spatial dimensions with two and five parameters. In the two‐dimensional spatial case with two parameters, it is shown that a 7 × 7 coefficient matrix is sufficient to accurately reproduce the expected solution, while in the five parameters problem, a 13 × 6 coefficient matrix is shown to reproduce the solution with sufficient accuracy. The proposed methodology is expected to find applications to parameter variation studies, uncertainty analysis, inverse problems and optimal design. Copyright © 2009 John Wiley & Sons, Ltd.     

Uniaxial Alignment of Conjugated Polymer Films for High‐Performance Organic Field‐Effect Transistors

Polymer semiconductors have been experiencing a remarkable improvement in electronic and optoelectronic properties, which are largely related to the recent development of a vast library of high‐performance, donor–acceptor copolymers showing alternation of chemical moieties with different electronic affinities along their backbones. Such steady improvement is making conjugated polymers even more appealing for large‐area and flexible electronic applications, from distributed and portable electronics to healthcare devices, where cost‐effective manufacturing, light weight, and ease of integration represent key benefits. Recently, a strong boost to charge carrier mobility in polymer‐based field‐effect transistors, consistently achieving the range from 1.0 to 10 cm² V^?1 s^?1 for both holes and electrons, has been given by uniaxial backbone alignment of polymers in thin films, inducing strong transport anisotropy and favoring enhanced transport properties along the alignment direction. Herein, an overview on this topic is provided with a focus on the processing–structure–property relationships that enable the controlled and uniform alignment of polymer films over large areas with scalable processes. The key aspects are specific molecular structures, such as planarized backbones with a reduced degree of conformational disorder, solution formulation with controlled aggregation, and deposition techniques inducing suitable directional flow.     

Ultrathin and Switchable Nanoporous Catalytic Membranes of Polystyrene‐b‐poly‐4‐Vinyl Pyridine Block Copolymer Spherical Micelles

An easy fabrication of close‐packed and block copolymer micelles‐based ultrathin membranes for water purification, separation, catalytic, and dye degradation applications is reported. Nanoporous membranes based on the self‐assembly of 2‐(4′‐hydroxybenzeneazo) benzoic acid (HABA)‐polystyrene‐b‐poly(4‐vinylpyridine) (PS‐b‐P4VP) diblock copolymers supramolecular complexes are prepared by simple spin coating on pore‐filled polyethylene terephthalate (PET) track‐etched membranes. The prepared membranes are characterized by scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and water permeation studies. The separation performance is studied by lysozyme protein rejection. The prepared membranes are also used to in situ synthesize gold nanoparticles in the corona of PS‐b‐P4VP spheres for catalytic activity towards the reduction of p‐nitrophenol and degradation of congo red dye in flow through operation mode in a stirred cell membrane reactor. More than 95% reduction for p‐nitrophenol and >98% degradation of Congo red at a sufficiently high flux indicates its suitability for catalytic transformation and environmental remediation applications.     

Diketopyrrolopyrrole (DPP)‐Based Donor–Acceptor Polymers for Selective Dispersion of Large‐Diameter Semiconducting Carbon Nanotubes

Low‐bandgap diketopyrrolopyrrole (DPP)‐based polymers are used for the selective dispersion of semiconducting single‐walled carbon nanotubes (s‐SWCNTs). Through rational molecular design to tune the polymer–SWCNT interactions, highly selective dispersions of s‐SWCNTs with diameters mainly around 1.5 nm are achieved. The influences of the polymer alkyl side‐chain substitution (i.e., branched vs linear side chains) on the dispersing yield and selectivity of s‐SWCNTs are investigated. Introducing linear alkyl side chains allows increased polymer–SWCNT interactions through close π–π stacking and improved C–H–π interactions. This work demonstrates that polymer side‐chain engineering is an effective method to modulate the polymer–SWCNT interactions and thereby affecting both critical parameters in dispersing yield and selectivity. Using these sorted s‐SWCNTs, high‐performance SWCNT network thin‐film transistors are fabricated. The solution‐deposited s‐SWCNT transistors yield simultaneously high mobilities of 41.2 cm² V^?1 s^?1 and high on/off ratios of greater than 10⁴. In summary, low‐bandgap DPP donor–acceptor polymers are a promising class of polymers for selective dispersion of large‐diameter s‐SWCNTs.     

Proteolytically Degradable Photo‐Polymerized Hydrogels Made From PEG–Fibrinogen Adducts

We develop a biomaterial based on protein–polymer conjugates where poly(ethylene glycol) (PEG) polymer chains are covalently linked to multiple thiols on denatured fibrinogen. We hypothesize that conjugation of large diacrylate‐functionalized linear PEG chains to fibrinogen could govern the molecular architecture of the polymer network via a unique protein–polymer interaction. The hypothesis is explored using carefully designed shear rheometry and swelling experiments of the hydrogels and their precursor PEG/fibrinogen conjugate solutions. The physical properties of non‐cross‐linked and UV cross‐linked PEGylated fibrinogen having PEG molecular weights ranging from 10 to 20 kDa are specifically investigated. Attaching multiple hydrophilic, functionalized PEG chains to the denatured fibrinogen solubilizes the denatured protein and enables a rapid free‐radical polymerization cross‐linking reaction in the hydrogel precursor solution. As expected, the conjugated protein‐polymer macromolecular complexes act to mediate the interactions between radicals and unsaturated bonds during the free‐radical polymerization reaction, when compared to control PEG hydrogels. Accordingly, the cross‐linking kinetics and stiffness of the cross‐linked hydrogel are highly influenced by the protein–polymer conjugate architecture and molecular entanglements arising from hydrophobic/hydrophilic interactions and steric hindrances. The proteolytic degradation products of the protein–polymer conjugates proves to be were different from those of the non‐conjugated denatured protein degradation products, indicating that steric hindrances may alter the proteolytic susceptibility of the PEG–protein adduct. A more complete understanding of the molecular complexities associated with this type of protein‐polymer conjugation can help to identify the full potential of a biomaterial that combines the advantages of synthetic polymers and bioactive proteins.     

An All‐Integrated Anode via Interlinked Chemical Bonding between Double‐Shelled–Yolk‐Structured Silicon and Binder for Lithium‐Ion Batteries

The concept of an all‐integrated design with multifunctionalization is widely employed in optoelectronic devices, sensors, resonator systems, and microfluidic devices, resulting in benefits for many ongoing research projects. Here, maintaining structural/electrode stability against large volume change by means of an all‐integrated design is realized for silicon anodes. An all‐integrated silicon anode is achieved via multicomponent interlinking among carbon@void@silica@silicon (CVSS) nanospheres and cross‐linked carboxymethyl cellulose and citric acid polymer binder (c‐CMC‐CA). Due to the additional protection from the silica layer, CVSS is superior to the carbon@void@silicon (CVS) electrode in terms of long‐term cyclability. The as‐prepared all‐integrated CVSS electrode exhibits high mechanical strength, which can be ascribed to the high adhesivity and ductility of c‐CMC‐CA binder and the strong binding energy between CVSS and c‐CMC‐CA, as calculated based on density functional theory (DFT). This electrode exhibits a high reversible capacity of 1640 mA h g^?1 after 100 cycles at a current density of 1 A g^?1, high rate performance, and long‐term cycling stability with 84.6% capacity retention after 1000 cycles at 5 A g^?1.     

Amino‐Functionalized ZIF‐7 Nanocrystals: Improved Intrinsic Separation Ability and Interfacial Compatibility in Mixed‐Matrix Membranes for CO2/CH4 Separation

Highly permeable and selective, as well as plasticization‐resistant membranes are desired as promising alternatives for cost‐ and energy‐effective CO₂ separation. Here, robust mixed‐matrix membranes based on an amino‐functionalized zeolitic imidazolate framework ZIF‐7 (ZIF‐7‐NH₂) and crosslinked poly(ethylene oxide) rubbery polymer are successfully fabricated with filler loadings up to 36 wt%. The ZIF‐7‐NH₂ materials synthesized from in situ substitution of 2‐aminobenzimidazole into the ZIF‐7 structure exhibit enlarged aperture size compared with monoligand ZIF‐7. The intrinsic separation ability for CO₂/CH₄ on ZIF‐7‐NH₂ is remarkably enhanced as a result of improved CO₂ uptake capacity and diffusion selectivity. The incorporation of ZIF‐7‐NH₂ fillers simultaneously makes the neat polymer more permeable and more selective, surpassing the state‐of‐the‐art 2008 Robeson upper bound. The chelating effect between metal (zinc) nodes of fillers and ester groups of a polymer provides good bonding, enhancing the mechanical strength and plasticization resistance of the neat polymer membrane. The developed novel ZIF‐7 structure with amino‐function and the resulting nanocomposite membranes are very attractive for applications like natural‐gas sweetening or biogas purification.     

Diffusion and Interaction Dynamics of Individual Membrane Protein Complexes Confined in Micropatterned Polymer‐Supported Membranes

Micropatterned polymer‐supported membranes (PSM) are established as a tool for confining the diffusion of transmembrane proteins for single molecule studies. To this end, a photochemical surface modification with hydrophobic tethers on a PEG polymer brush is implemented for capturing of lipid vesicles and subsequent fusion. Formation of contiguous membranes within micropatterns is confirmed by scanning force microscopy, fluorescence recovery after photobleaching (FRAP), and super‐resolved single‐molecule tracking and localization microscopy. Free diffusion of transmembrane proteins reconstituted into micropatterned PSM is demonstrated by FRAP and by single‐molecule tracking. By exploiting the confinement of diffusion within micropatterned PSM, the diffusion and interaction dynamics of individual transmembrane receptors are quantitatively resolved.     

General model of hydrogen transport through nanoporous membranes

A general model of transport of gases in solid nanoporous membranes was established. The model was developed based on Dusty Gas Model (DGM), solution diffusion and surface diffusion. As a result, solutions of the model for different transport conditions were derived. In this investigation, parameters of hydrogen gas transport of vinyl film (polymer) and vycor glass membranes were used to calculate semi-empirical solutions of the general model. In other words, the solutions of the general model were analytically obtained for different transport conditions, using experimentally obtained parameters of hydrogen gas transport in vinyl film (polymer) and vycor glass membranes. The obtained solutions of the general model were for the hydrogen transport of the membranes in the non-porous, nanoporous, microporous, and to macroporous range. The model was found useful for predictions of hydrogen transport through solid membranes. Additionally the model can be ready used for other gases for predictions of the transport of gases in nanoporous membranes.