Polystyrene films monodisperse

Kajiyama, T., Tanaka, K. and Takahara, A. (1997) Surface molecular motion of the monodisperse polystyrene films. Macromohcules, 30, 280-285. 

For example, enhanced macromolecular mobility was observed at the surface of polystyrene films [33]. In 200 nm thick films of monodisperse PS on silicon, measurements of the lateral force (under a constant applied load of 10 nN) vs. 

In this paper we will compare different experiments in contact and with an oscillating tip to show their contribution for the study of soft material. In static contact mode, force curves and friction loops are recorded while in tapping a systematic investigation of approach-retract curves is presented. A model sample is used monodisperse polystyrene films of different molecular weights (MJ bulk mechanical properties and molecular weight dependence of the glass transition temperature. In order to emphasize the inherent difficulties encountered with an AFM, we begin with a detailed discussion of the technical conditions. 

Tanaka K, Taura A, Ge SR, Takahara A, Kajiyama T. Molecular weight dependence of surface dynamic viscoelastic properties for the monodisperse polystyrene film. Macromolecules 1996 29 3040-3042. 

In the same year, Fulda and Tieke [75] reported on Langmuir films of monodisperse, 0.5-pm spherical polymer particles with hydrophobic polystyrene cores and hydrophilic shells containing polyacrylic acid or polyacrylamide. Measurement of ir-A curves and scanning electron microscopy (SEM) were used to determine the structure of the monolayers. In subsequent work, Fulda et al. [76] studied a variety of particles with different hydrophilic shells for their ability to form Langmuir films. Fulda and Tieke [77] investigated the influence of subphase conditions (pH, ionic strength) on monolayer formation of cationic and anionic particles as well as the structure of films made from bidisperse mixtures of anionic latex particles. 

For the characterization of Langmuir films, Fulda and coworkers [75-77] used anionic and cationic core-shell particles prepared by emulsifier-free emulsion polymerization. These particles have several advantages over those used in early publications First, the particles do not contain any stabihzer or emulsifier, which is eventually desorbed upon spreading and disturbs the formation of a particle monolayer at the air-water interface. Second, the preparation is a one-step process leading directly to monodisperse particles 0.2-0.5 jim in diameter. Third, the nature of the shell can be easily varied by using different hydrophilic comonomers. In Table 1, the particles and their characteristic properties are hsted. Most of the studies were carried out using anionic particles with polystyrene as core material and polyacrylic acid in the shell. 

Monodispersed polystyrene sols are used as calibration standards for electron microscopes, light scattering photometers, Coulter counters, particle sieves, etc. Monodispersed silica is used for antireflection lens coatings. Monodispersity (even at a modest level) can usefully be exploited in photographic film, magnetic devices, pharmaceutical preparations and catalysis. 

Figure 2. Ratio of anthracene and carbazole emission intensities from freeze-dried mixtures of monodisperse polystyrene (M - 410,000) carrying 0.0092 moles/kg of the labels, relative to this ratio in films cast from solutions of a mixture of these polymers. Excitation at the carbazole absorption peak at 294 nm. Original solution in benzene dioxane (D) and cyclohexane (0). Arrows indicate l/iq] in the various solvents.

The same phenomenon was observed for ionic surfactant solutions (16, 55), such as a-olefin sulfonates (1), but here the height of the steps was close to the effective micellar diameter, which includes the electric double layer around the ionic micelles. Furthermore, foam films formed from concentrated monodisperse suspensions of polystyrene latexes (16) or silica particles (56) stratify in a similar way. 

Bartlett PN, Baumberg JJ, Birkin PR, Ghanem MA, Netti MC (2002) Highly ordered macroporous gold and platinum films formed by electrochemical deposition through templates assembled from submicron diameter monodisperse polystyrene spheres. Chem Mater 14 2199... 

Abstract In this review, we show the distribution of glass transition temperature (Tg) in monodisperse polystyrene (PS) films coated on silicon oxide layers along the direction normal to the surface. Scanning force microscopy with a lateral force mode revealed that surface T (Tl) was lower than the corresponding bulk T, (T ). 

An alternative approach to fabricate a superhydrophobic surface on a device is to utilize the nanoimprint technique to create nanostructures on the chip surfaces, which are coated with a thin film of hydrophobic materials. The fabrication scheme for a superhydrophobic surface using nanoimprint is illustrated in Fig. 2. To conduct nanoimprint lithography, the first step is to fabricate the stamp for nanoimprint. Previously [24-26], we demonstrated a simple technique to fabricate nanoimprint stamp by nanosphere lithography. In this process, a monodispersed polystyrene dispersion with 400 nm diameter beads (Bangs Laboratories, Inc., Fishers, IN) was... 

The mostly used methods to monitor LbL deposition on monodisperse PS-latex particles for various substances are SPLS method and microelectrophoresis. Inorganic (magnetite, silica, titania and fluorescent quantum dots) nanoparticles [32-34], lipids [35-37] and proteins (albumin, immunoglobulin and others) [29, 38, 39] were incorporated as building block for shell formation on colloidal particles. In paper [39] the construction of enzyme multilayer films on colloidal particles for biocatalysis was demonstrated. The enzyme multilayers were assembled on submicrometer-sized polystyrene spheres via the alternate adsorption of poly(ethyleneimine) and glucose oxidase. The high surface area bio-multilayer coated particles formed were subsequently utilized in enzymatic catalysis. The step-wise coating of different lipids alternated with polyelectrolytes was performed by adsorption of preformed vesicles onto... 

Experimental procedure used to fabricate two-dimensional arrays of polymeric microlenses on glass substrates, (a) Cross-sectional view of packing cell used to deliver monodispersed polystyrene beads into two-dimensional array of cylindrical holes patterned in thin film of PR spin coated on bottom glass substrate, (b) Fabrication of microlenses with hemispherical and mushroom-shaped profiles by annealing sample at temperatures above glass transition temperature of polystyrene ( 93°C). The formation of a hemispherical shape was driven by the minimization of the surface free energy. (Source Lu, Y., Y.D. Yin, and Y.N. Xia. 2001. Advanced Materials, 13(1), 34-37. With permission.)... 

Dried films of certain monodisperse polystyrene latexes display brilliant iridescent colors. These colors have been attributed to the diffraction of visible light by latex particle crystallites (46-48). When dried at room temperature, polystyrene latexes form opaque, white, friable, discontinuous films. Electron micrographs of surface replicas of these films show the monodisperse spheres packed in uniform hexagonal arrays without appreciable coalescence (49). If the distance between the particle centers is within a certain range, the crystallite diffracts visible light and the interference colors are observed. These color combinations are specific for the latex particle diameter (Table VII). 

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