对聚合物玻璃化转变的几点新认识

基于聚合物玻璃化转变的定义,探讨了聚合物宏观单晶体和聚合物单链单晶的玻璃化转变问题,指出玻璃化转变的温度依赖性不服从普适的Arrhenius方程,可以把WLF方程看作是聚合物玻璃化转变的特有温度依赖关系。介绍了二维状态下聚合物可能的玻璃化转变。     

Preparation of refractive index matching polymer film alternative to oil for use in a portable surface-plasmon resonance phenomenon-based chemical sensor method

In order to simplify the procedure for assembling a surface-plasmon resonance (SPR) sensor, a refractive index matching polymer film was prepared as an alternative to the conventionally used matching oil. The refractive index matching polymer film, the refractive index of which was nearly equal to the prism and sensor chip material (a cover glass) of the SPR sensor, was prepared by casting a tetrahydrofuran solution of poly (vinyl chloride) (PVC) containing equal weights of dioctyl phthalate and tricresyl phosphate. The refractive index matching polymer film was found to have a refractive index of 1.516, which is identical to that of the prism and the cover glass used for the present SPR sensor. The utility of the matching polymer film for the SPR sensor was confirmed by the detection of anti-human albumin, based on an antigen-antibody reaction.     

Electrohydrodynamic effect on phase separation morphology in polymer blend films

We have investigated the effect of electrohydrodynamic (EHD) convection on the domain structure in a polystyrene (PS)/polyvinyl acetate (PVA) blend film to demonstrate the feasibility of using the EHD effect as a means of mixing and morphology control in a polymer blend film prepared by solvent evaporation. Here, polymers-toluene solutions were spread on a glass substrate with patterned electrodes to apply a dc electric field, and well-defined structures of EHD convection were formed in the polymer solutions. As a result, regular patterns were formed in the PS/PVA polymer blend film in which PVA-rich domains were confined within each unit of patterned electrodes, i.e., between positive and negative electrodes, at an appropriate electric voltage. In addition, it was demonstrated that such novel morphology is not due to the wetting/dewetting effect of polymer components to the Pt electrodes deposited on the glass substrate, by experiments with a SiO2-covered substrate.     

Mechanism of plasma-initiated polymerization: Concerning the nature of solvent effects on the lifelike polymerization of water-soluble vinyl monomers

To provide a satisfactory basic understanding of the solvent effect of plasma-initiated polymerization, we have carried out several kinds of polymerizations of various water-soluble vinyl monomers. It has been shown that aqueous solution of such vinyl monomers underwent the polymerizations induced by methyl isobutyrate (MIB) plasma-exposed glass surface. The invisible ultrathin polymer film trapping an active radical species deposited on the plasma-exposed glass surface apparently induced the polymerizations. The efficiency, however, was largely dependent on the solvent used: the solvent can be considered to act as “an initiation-activator” for the lifelike postpolymerization. The nature of the solvent effect was ascribed to the physicomechanical property such as swelling ability and/or solubility toward the ultrathin film formed on the glass surface. Thus it has been suggested that the choice of good-balanced combination between the structural feature of the plasma-induced ultrathin polymer film and the solvent as an initiation-activator is important to achieve activity of a desired solution polymerization.     

Substrate- and time-dependent photoluminescence of quantum dots inside the ultrathin polymer LbL film

The photoluminescence of CdSe/ZnS quantum dots (QDs) in different configurations at solid surfaces (glass, silicon, PDMS, and metals) is considered for three types of organization: QDs directly adsorbed on solid surfaces, separated from the solid surface by a nanoscale polymer film with different thickness, and encapsulated into a polymer film. The complete suppression of photoluminescence for QDs on conductive metal surfaces (copper, gold) indicated a strong quenching effect. The temporal variation of the photoluminescent intensity on other substrates (glass, silicon, and PDMS) can be tuned by placing the nanoscale (3-50 nm) LbL polymer film between QDs and the substrate. The photooxidation and photobleaching processes of QD nanoparticles in the vicinity of the solid surface can be tuned by proper selection of the substrate and the dielectric nanoscale polymer film placed between the substrate and QDs. Moreover, the encapsulation of QD nanoparticles into the polymer film resulted in a dramatic initial increase in the photoemission intensity due to the accelerated photooxidation process. The phenomenon of enhanced photoemission of QDs encapsulated into the ultrathin polymer film provides not only the opportunity for making flexible, ultrathin, QD-containing polymer films, transferable to any microfabricated substrate, but also improved light emitting properties.     

聚藏红T修饰电极的制备及对多巴胺的电催化性能

用循环伏安法在石墨电极和ITO导电玻璃上制备了藏红T聚合物薄膜修饰电极,研究了电聚合过程及循环伏安性质.聚藏红T膜修饰石墨电极在pH 6.81的PBS中循环扫描,有两对氧化还原峰,峰电位分别为Ep,a(P1)=-0.5 V,Ep,c(P1)=-0.575 V,Ep,a(P2)=-0.36 V,Ep,c(P2)=-0.425 V,而且聚合物较稳定.测定了聚藏红T膜的可见光谱性质.实验表明,聚藏红T膜修饰电极对多巴胺有明显的催化作用.     

Solute diffusion in relation to the glass transition temperature of solute-polymer blends

The transport of various dye solute molecules from amorphous donor polymer films to an amorphous acceptor polymer film has been investigated. Dye diffusion was studied by laminating dye-donor and dye-acceptor films under controlled pressure and temperature. The acceptor medium was kept constant, whereas a wide range of polymer structures were used as binders in the donor system. At constant dye concentration, the transport of the dye molecules from the donor sheet was found to be controlled by the glass transition temperature of the dye-polymer mixture in the donor film. This relationship was ubiquitous for all types of chromophore and polymer studied. The data was found to fit well with free volume considerations and the Williams-Landel-Ferry equation by using the glass transition as that of the dye-polymer blend in the donor matrix.     

Thermally activated nanowear modes of a polymer surface induced by a heated tip

We report on nanoscale wear induced by atomic force microscopy using a heated cantilever/tip on a 20 nm thick film of polystyrene. Wear modes dependent on tip temperature characteristics were identified. Below the glass transition temperature of the polymer, the formation of quasi one-dimensional surface ripples with a typical period on the order of 100 nm was observed. We found that the ripple height typically saturates at 20 nm and that the buildup rate depends on temperature and load. From these observations we can calculate an activation energy for the ripple formation, which is on the order of 0.4 eV, at temperatures close to but below the glass transition temperature of the polymer. In the glass transition regime the ripple formation is strongly enhanced. An abrupt change of the wear mode is observed as the polymer in contact with the tip is heated above the glass transition temperature. Here, polymer material is transported along with the propagating tip.     

Polystyrenes with structurally different oligosiloxanes as p-substituents for oxygen permeable membrane materials

Polystyrenes with structurally different oligosiloxanes as p-substituents were synthesized and the selective oxygen permeation through the polymer film was studied. It was found that the structure of the p-oligosiloxane substituents had great effects not only on the glass transition temperature of the polymer but also on the oxygen permeation behavior through the polymer film. Trimethylsiloxyl groups, especially, were shown to play an essential role in enhancing the permeability.     

界面张力在基板诱导共混物分散相粒子粗化生长加速现象中的作用

通过相差显微镜和计算机图像处理来研究两相聚合物体系的粗化过程 .将具有不同聚比的乙烯 聚醋酸乙烯酯 (EVAc)共聚物与聚丙烯 (PP)共混 ,制备不同相界面张力的系列共混物薄膜 .观察了在玻璃基板的作用下 ,不同界面张力体系的分散相粒子粗化行为 ,发现界面张力在约 0 4 8·1 0 - 5N cm以上的体系中分散相粒子的粗化有明显的加速现象 ,粒子体积生长与时间关系的指数大于 1 0 ;而两相界面张力较低的情况下 ,选择具有不同表面极性的基板对同一体系试验 ,我们均未发现有粗化加速现象产生 ,且采用不同基板之间的试验结果差异很小 ,亦即当高分子共混物的相界面张力大于一定值时 ,仅与基板存在有关 ,粒子的粗化行为被加速     

A novel method of preparing of glass capillary columns: Low-temperature plasma etching and polymerization

A novel method is described for the preparation of stable glass capillary columns (glass open tubular columns), including the etching and formation of a polymer film on the inner glass capillary surfaces. The approach used here is based on low-temperature plasma etching and polymerization. Under the influence of a field of radio frequency discharge, low pressure gases of fluoric compounds, introduced into the glass capillary tube, generate excited fluorine radicals which etch the inner surface. The plasma of organosilicone monomer in the glass capillary yields a uniform polymerized film on the inner surface. The resultant material functions as a good stationary phase for glass capillary gas chromatography (GC²). The inner surfaces treated with such a plasma, can be studied by means of a scanning electron microscope (SEM). The flexibility of this method permits the use of various stationary phases and surface modification.     

The influence of different factors on exploitation properties of nonlinear optical polymeric materials based on an epoxy matrix doped with flavonoids

The paper is devoted to investigations of exploitation properties of nonlinear-optical (NLO) polymer film materials based on an epoxy matrix doped with flavonoids. Adhesion of the polymer films to a glass substrate is investigated. Also, the influence of photoinduced destruction on functional properties of these polymer composites by UV–Vis spectroscopy method is studied. Effect of various microorganisms such as mold fungi of Aspergillus niger (A. niger) and Pinicillum chrysogenum (P. chrysogenum) species on the polymer NLO materials are analyzed by evaluation of the fungistatic effect and fungicidal resistance and using the FTIR spectroscopy. As a result it is established that the NLO polymer film materials based an epoxy matrix doped with flavonoids have a very good adhesion to the glass substrate, and they are stable to the photoinduced destruction. These materials do not have the fungistatic effect but they demonstrate some fungicidal resistance. This phenomenon is explained by the presence of flavonoids, which are natural antiseptics.     

An investigation on the influence of a vinyl pyrrolidone/vinyl acetate copolymer on the moisture permeation, mechanical and adhesive properties of aqueous-based hydroxypropyl methylcellulose film coatings

Polymers for aqueous film coating, such as hydroxypropyl methylcellulose (HPMC), often require the inclusion of a plasticizer to reduce brittleness and increase flexibility and ductility. A vinyl pyrrolidone/vinyl acetate copolymer (S630) was investigated for its influence on HPMC film coating parameters, comparing the results with a commonly used plasticizer, polyethylene glycol and another copolymer, polyvinyl alcohol. The viscous properties of the solutions and the glass transition temperatures of the equivalent polymer films were evaluated. Its effect on the film properties, such as appearance, surface roughness, moisture permeation and mechanical properties, as well as its ability to promote better adhesion of the film coat to the core surface, was compared. S630 was able to reduce the viscosity of the polymer solution and glass transition temperature of HPMC, as well as, enhance the mechanical properties of the cast film. The moisture permeation was slightly reduced but not to the same extent as polyethylene glycol. A 10% concentration of S630 increased the adhesive strength and toughness of the HPMC film coat. In conclusion, S630 was effective as a film-former, substrate adhesive and plasticizer. It has the potential to be used to replace the more volatile plasticizers which have problems of loss or migration.     

A Brush‐Gel/Metal‐Nanoparticle Hybrid Film as an Efficient Supported Catalyst in Glass Microreactors

A polymer‐brush‐based material was applied for the formation and in situ immobilization of silver and palladium nanoparticles, as a catalytic coating on the inner wall of glass microreactors. The brush film was grown directly on the microchannel interior by means of atom‐transfer radical polymerization (ATRP), which allows control over the polymer film thickness and therefore permits the tuning of the number of nanoparticles formed on the channel walls. The wide applicability of the catalytic devices is demonstrated for the reduction of 4‐nitrophenol and for the Heck reaction.     

Application of Polyaniline Film as a Sensor for Stimulant Nerve Agents

Abstract

Methyl phosphonic dichloride (MPDC) and dimethyl methyl phosphonate (DMMP) are two important organophosphorus compounds used in the preparation of many toxic organophosphorus compounds such as nerve agents. This paper deals with the application of polyaniline coated on a glass slide surface as a sensor for the detection of some of the stimulant nerve agents such as MPDC and DMMP. The sensing behavior of polyaniline films toward MPDC and DMMP vapors via electrical conductivity changes of the polymer film using the standard four-point probe technique was investigated. The effects of the chemical concentration and the polymer thickness on the conductivity and conductivity stability of the polymer were also studied. The vapors of nerve agent stimulants affect the PANi film by the p-doping mechanism and lead to an increase in the conductivity of the polymer. The response times of the PANi film to MPDC and DMMP vapors are very fast, and the conductivity of the polymer increases with the increase in the concentration of the samples.     

Demonstration of a novel,flexible, photocatalytic oxygen-scavenging polymer film

The preparation of a novel, flexible, photocatalytic, oxygen-scavenging polymer film is described. The film incorporates nanocrystalline titania particles in an ethyl cellulose polymer film, with or without an added sacrificial electron donor of triethanolamine. When coated on the inside of a glass vessel its UV-driven light-scavenging action is demonstrated by platinum octaethyl porphyrin coated glass beads sealed inside, since their luminescence increases with increasing UV-irradiation time. When used as a flexible film, work with an oxygen electrode shows that the film is able to scavenge oxygen at an average rate of 0.017 cm³ O₂ h⁻¹ cm⁻² over a 24 h period, which compares favourably to other, well-established oxygen-scavenger systems. The potential of using such as system for oxygen scavenging in packaging is discussed briefly.     

Fabrication of Ordered Arrays of Biodegradable Polymer Pincushions Using Self-Organized Honeycomb-Patterned Films

Nano- and micropatterned structures of tissue engineering scaffolds made of biodegradable and biocompatible polymers profoundly influence cell behavior. The present study describes a technically simple and inexpensive method to rapidly fabricate hexagonal arrays of biodegradable polymer pillars (pincushions). As precursors to these polymer pincushion arrays, highly regular porous biodegradable polymer films (self-organized honeycomb-patterned films, called honeycomb films) were prepared on a glass substrate using a simple casting technique. Scanning electron microscope observations revealed that the honeycomb film was composed of a top and bottom layer. This double-layered structure is attributable to the self-organization of hexagonally packed arrays of water droplets that form the template. When we peeled off the top layer of the honeycomb film under ambient conditions using adhesive tape, we obtained arrays of polymer pincushions on both side of the glass substrate and on the adhesive tape. Each air hole is surrounded by six pincushions, each with a diameter of 0.1-1 µm. We also studied factors that determine the morphology of the pincushions, such as the thermal and mechanical properties of the polymers used. It was shown that the heights, widths, and distances of separation between the pincushions could be controlled by the choice of polymer and the pore structure of the original honeycomb film. Such well-ordered, biologically inspired pincushion structures could find application in biomedical, photonic, and electronic materials.     

Drying dissipative structures of aqueous solution of poly(ethylene glycol) on a cover glass, a watch glass, and a glass dish

Drying dissipative structures of aqueous solution of poly(ethylene glycol) (PEG) of molecular weights ranging from 200 to 3,500,000 were studied on a cover glass, a watch glass, and a glass dish on macroscopic and microscopic scales. Any convectional and sedimentation patterns did not appear during the course of drying the PEG solutions. Several important findings on the drying patterns are reported. Firstly, the crystalline structures of the dried film changed from hedrites to spherulites as the molecular weight and/or concentration of PEG increased. Secondly, lamellae were formed along the ring patterns especially at high concentrations and high molecular weights. The coupled crystalline patterns of the spherulites and the lamellae were observed in a watch glass along the ring structures, supporting the important role of the convection by the gravity during the course of dryness. The coupled patterns were difficult to be formed on a cover glass and a glass dish, except at the outside edge of the dried film. Thirdly, the size of the broad ring at the outside edge of the dried film especially on a cover glass and a watch glass increased sharply as the molecular weight increased and also as the polymer concentration increased. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Temperature effect on the rubbing-induced optical phase retardation of a side group liquid crystalline polymer film

Recently we observed an unusual temperature dependence of the pretilt angle of a nematic liquid crystal generated at the rubbed surface of a side group liquid crystalline polymer film. To understand the mechanism, a detailed investigation of the temperature effect on the rubbing-induced optical phase retardation of a side group liquid crystalline polymer film has been carried out. On heating the film above the glass transition temperature of the polymer, a clear change is seen in the temperature dependence of the optical phase retardation. We infer from this investigation that the thermal variation of the rubbing-induced optical phase retardation results in a change in the temperature variation of the pretilt angle.     

High‐Density Liquid‐Crystalline Polymer Brushes Formed by Surface Segregation and Self‐Assembly

High‐density polymer brushes on substrates exhibit unique properties and functions stemming from the extended conformations due to the surface constraint. To date, such chain organizations have been mostly attained by synthetic strategies of surface‐initiated living polymerization. We show herein a new method to prepare a high‐density polymer brush architecture using surface segregation and self‐assembly of diblock copolymers containing a side‐chain liquid‐crystalline polymer (SCLCP). The surface segregation is attained from a film of an amorphous base polymer (polystyrene, PS) containing a minor amount of a SCLCP‐PS diblock copolymer upon annealing above the glass‐transition temperature. The polystyrene portion of the diblock copolymer can work as a laterally mobile anchor for the favorable self‐assembly on the polystyrene base film.