Interaction of proteins with ultrafiltration membranes: Development of a nonfouling index test

Ultrafiltration membranes were prepared from homopolymer [polyacrylonitrile (PAN), polyethersulfone (PES), and polyvivylidenefluoride (PVDF)] and acrylonitrile copolymers with increasing acrylamide content. The membranes containing acrylamide were more hydrophilic and had a smaller dispersive surface energy than those prepared from the acrylonitrile homopolymer. A new nonfouling index (NFI) test was devised and appears to distinguish well between ultrafiltration membranes of different hydrophilicity–hydrophobicity balance. The NFI indices of acrylamide containing copolymer membranes were much higher than those of membranes cast with commercial membrane materials such as PAN, PES, and PVDF. The NFI of ultrafiltration membranes increased as acrylamide substitution in the copolymer increased. The use of acrylamide containing copolymers substantially eliminated intrinsic fouling. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1600–1606, 2000     

Coating metal oxide particles via the combustion of deposited polymer precursors

Water-swellable chelated polymers were synthesized, starting either from (1) In(III) or In(III) and Sn(II) as central ions and N-trimethoxysilylpropylethylenediamine or ethylenediamine each together with ethylenediaminetetraacetic acid (EDTA) as coordination ligands, or from (2) Ag(I) as the central ion and ethylene glycol (EG) and EDTA as coordination ligands, as follows: The nitrate(s) of the above metal ions together with the corresponding ligands were dissolved in water, and the solution was concentrated by heating to carry out the chelating polymerization. After cooling, the polymer was dried and ground to a fine powder, which was then mixed with a metal oxide powder by grinding in the presence of a small amount of water. A paste was thus obtained, which, after drying, was calcined at 200°C and subsequently at 750°C. The polymer became a sticky gel at 200°C, which adhered to the surface of the metal oxide particles; it was converted to an inorganic coating, In₂O₃—SnO₂—SiO₂, In₂O₃—SnO₂, SnO₂, or Ag, during the subsequent calcination at 750°C. Two metal oxide powders, namely, the electrically conductive In₂O₃ and the nonconductive SnO₂, were used as substrates. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) indicated that the substrate particles were coated after calcination by a multicomponent oxide or silver layer. Temperature-resistant electrically antistatic film could be prepared by using the metal oxide coated In₂O₃ particles as pigments and polypropylsiloxane as the binder. The Ag-coated SnO₂ powder had a conductivity σ = 1.0 × 10⁻³ S cm⁻¹ at 8.6 vol % Ag, while the mechanically mixed powders of Ag and SnO₂ exhibited a conductivity of 2.0 × 10⁻⁷ S cm⁻¹ at 16 vol %. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1891–1903, 1998     

Flexible polyurethane foam. II. Fire retardation by tris(1,3-dichloro-2-propyl) phosphate. Part B. Examination of the condensed phase (the pyrolysis zone)

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) is used commercially as a fire retardant for flexible polyurethane foams. It was found to act both in the condensed (pyrolysis zone) and the vapor (flame) phases. The extent of its activity in the individual phases depends on the way in which the specimen is ignited. Under conditions of candle-like, top-down burning, retardation seems to occurs mainly in the condensed phase by a mechanism apparently based largely on the barrier properties of a phosphorus-containing carbonaceous layer that builds up on top of the liquid pyrolyzing layer beneath the flame. As the formation of this barrier requires time, extinguishment in this mode is relatively slow. Extinguishment is much faster in bottom-up burning, where the flame appears to be the main site of the retardation. In this mode, because of the orientation of the specimen relative to the flame, a disproportionately large amount of TDCPP enters the flame. It is proposed that TDCPP decomposition products, HCl and other low-fuel-value materials dilute the fuel vapors sufficiently to reduce their flame propagation velocity to below that at which they stream out of the pyrolysis zone. This pushes the flame away from the pyrolysis zone, uncoupling the thermal feedback mechanism that produces the fuel. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:231–254, 1998     

粘度法测定植物纤维素的聚合度

介绍了以饱和氢氧化铜的乙二胺溶液(CED)为溶剂,通过测定CED溶液和一定浓度的植物纤维素-CED溶液在粘度计毛细管中的流出时间,利用Martin公式计算出试样特性粘数后,由Mark方程计算植物纤维素的聚合度的方法。利用该方法测得的纤维素棉浆粕的平均聚合度为546-556;该法使用的仪器简单,且准确度较高,相对误差小于1．5％。     

Conductive coating films based on low density In2O3 powders and polymer latexes

Several kinds of conductive coating films were prepared from a low-density indium(III) oxide powder (which was employed because it provides a much higher volume for the same weight) and polymer latexes. The low-density In₂O₃, which is an electrically conductive pigment, was prepared by pyrolysis followed by the combustion of water-swellable polymer microspheres imbibed with In(NO₃)₃, the precursor of In₂O₃. Either acrylamide/N,N'-methylenebisacrylamide or poly(vinylalcohol)/glutaricdialdehyde was used to generate spherical hydrogel particles. The polymer latexes with which the In₂O₃ was mixed had a soft core and a hard shell structure to ensure that the coating film has suitable mechanical properties in addition to conductivity. Acrylonitrile/butadiene/styrene copolymer ABS or acrylonitrile/butylacrylate/styrene copolymer ABAS latexes were used as binders for the conductive pigment. The powder coating followed by hot pressing, the water-borne coating consisting of low-density In₂O₃ and polymer latexes followed by curing, or the colloidal dispersion coating was used to deposit flexible conductive coating films on polyester sheets. The conductive pigment density and the polymer latexes' size and flowability are the factors that affect the characteristics of the film. We found that the colloidal suspension coating procedure based on ABAS latexes achieves better electrical and mechanical properties for the coating films. © 1996 John Wiley & Sons, Inc.     

The concentrated emulsion approach to toughened polymer composites: A review

A series of tough polymers were prepared by combining flexible with rigid chains, using the method of concentrated emulsion polymerization. The tough materials obtained can be classified into four types: [a] those prepared via the polymerization of a monomer containing a dissolved elastomer, starting from its concentrated emulsion in water; [b] those prepared via heterogeneous (interfacial) crosslinking of two partially polymerized concentrated emulsion in water containing incipient latexes; [c] those prepared as semi-interpenetrating or AB network latexes, starting from a concentrated emulsion in water and [d] those prepared by mixing two partially polymerized concentrated emulsions and completing the polymerization. A concentrated emulsion differs from the conventional emulsion in that the volume fraction of the dispersed phase is higher than that of the most compact arrangement of monosize spheres (0.74) and can be as high as 0.99. The cells of a highly concentrated emulsion are no longer spherical, but polyhedral in shape, compactly packed and separated by thin films of continuous phase. As a result of such structure, a high polymerization rate and a high molecular weight can be achieved, the size (in the colloidal range) of the flexible phase can be controlled and the latter phase can be uniformly dispersed in the rigid one. Consequently, the concentrated emulsion method constitutes a suitable pathway to toughened composites. Owing to the compact packing of cells, the concentrated emulsion polymerization method is particularly suitable for cases in which reactions occur at the cell interface. For the materials of type [d], these reactions generate quasi-block copolymers, which compatibilize (via “auto-compatibilization”) the components of blends.     

Self-Assembly of Mixed-Dimensional GeS1−xSex (1D Nanowire)–(2D Plate) Van der Waals Heterostructures

The integration of dissimilar materials into heterostructures is a mainstay of modern materials science and technology. An alternative strategy of joining components with different electronic structure involves mixed-dimensional heterostructures, that is, architectures consisting of elements with different dimensionality, for example, 1D nanowires and 2D plates. Combining the two approaches can result in hybrid architectures in which both the dimensionality and composition vary between the components, potentially offering even larger contrast between their electronic structures. To date, realizing such heteromaterials mixed-dimensional heterostructures has required sequential multi-step growth processes. Here, it is shown that differences in precursor incorporation rates between vapor–liquid–solid growth of 1D nanowires and direct vapor–solid growth of 2D plates attached to the wires can be harnessed to synthesize heteromaterials mixed-dimensional heterostructures in a single-step growth process. Exposure to mixed GeS and GeSe vapors produces GeS_1−xSe_x van der Waals nanowires whose S:Se ratio is considerably larger than that of attached layered plates. Cathodoluminescence spectroscopy on single heterostructures confirms that the bandgap contrast between the components is determined by both composition and carrier confinement. These results demonstrate an avenue toward complex heteroarchitectures using single-step synthesis processes.     

Solution-processed high-performance organic light-emitting diodes containing a green-emitting multiresonant thermally activated delayed fluorescent dendrimer

A multi-resonance thermally activated delayed fluorescence (MR-TADF) dendrimer emitter and a related reference MR-TADF compound were designed, synthesized, and characterized for use as narrowband emitters in solution-processed OLEDs. The 1 wt% doped films in PMMA film revealed that the compounds MR-D1 and MR-D2 showed narrowband green emission at λ_PL of 490 and 495 nm and with FWHM of 23 and 29 nm, respectively. The 50 wt% doped films in mCP still show narrowband green emission at λ_PL of 495 and 499 nm and with FWHM of 28 nm for MR-D1 and MR-D2 , respectively, while conserving the small ΔE_ST of 0.14 and 0.13 eV, respectively. OLEDs containing an emissive layer consisting of 50 wt% MR-D1 and MR-D2 in mCP showed high EQE_max of 27.7% and 21.0%, respectively, and low efficiency roll-off of 19% and 30% at a luminance of 2000 cd/m⁻².     

“Magic Numbers” in Self-Faceting of Alcohol-Doped Emulsion Droplets

Oil-in-water emulsion droplets spontaneously adopt, below some temperature T_d, counterintuitive faceted and complex non-spherical shapes while remaining liquid. This transition is driven by a crystalline monolayer formed at the droplets' surface. Here, we show that ppm-level doping of the droplet's bulk by long-chain alcohols allows tuning T_d by >50 °C, implying formation of drastically different interfacial structures. Furthermore, “magic” alcohol chain lengths maximize T_d. This we show to arise from self-assembly of mixed alcohol:alkane interfacial structures of stacked alkane layers, co-crystallized with hydrogen-bonded alcohol dimers. These structures are accounted for theoretically and resolved by direct cryogenic transmission electron microscopy (cryoTEM), confirming the proposed structures. The discovered tunability of key properties of commonly-used emulsions by minute concentrations of specific bulk additives should benefit these emulsions' technological applicability.     

Synthesis and characterisation of antioxidant‐modified esters of dipentaerythritol as lubricating base oil

In this paper, five antioxidant‐modified esters were synthesised through two steps of simple esterification. Antioxidant‐modified multi‐hydroxyl compound was synthesised at the first step, and antioxidant‐modified esters were synthesised at the second step. This kind of esters is useful in many fields, such as lubricating oil and cutting compound, because of two important functions (antioxidant and lubricant) in the same compound. The active antioxidant group attached to these esters was 3‐(3,5‐di‐tert‐butyl‐4‐hydroxy‐phenyl)‐propionic acid. The esters were characterised with Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) analysis. The analytical results of FTIR demonstrates the changes of alcoholic hydroxyl and carboxyl and suggests that this synthesis was feasible. The TG analysis and rotating pressure vessel method show that this kind of esters has excellent oxidative stability. The physical properties of lubricating base oil, such as viscosity, viscosity index, pour point and flash point, suggested that this kind of esters can be used as lubricating base oil. Copyright © 2012 John Wiley & Sons, Ltd.