Cast thin films

Another example of favorable synergistic effects in ionomer/homopolymer blends is evident from a study of the tensile properties of blends of an SPS ionomer with PS. Over most of the composition range these two polymers are incompatible. For small additions of the SPS ionomer to PS, TEM studies of cast thin films show that... 

Figure 11.21 Polyphosphazenes (a) processed into gaskets, O-rings and flexible hoses and (b) solution-cast thin films. Reproduced with permission from J. E. Mark, H. R. Allcock and R. West, Inorganic Polymers, 2nd edn., Oxford University Press, Toronto, 2005. ...

Microdomains of block copolymer/ homopolymer blends 25-A-diameter Pd clusters Metal-ion precursors, introduced into cast thin films of polymer microdomains, are reduced by high pressure hydrogen 60,61... 

It is possible to cast thin films from PVDF aqueous dispersions. They can be pigmented and used for decorative surfaces.20 PVDF aqueous dispersions alone or their blends with acrylic aqueous systems are used for coating fabrics or as decorative or protective coatings. 

Reticulate composites comprising needles of TTT-TCNQ (tetrathiotetra-cene-tetracyaiioquinodimethane) in poly(bisphenol-A-carbonate) were first described in the early 1980s. The composites were prepared by casting thin films from a solution of the components in o-dichloromethane. The composite contained a network of fine interconnected needle crystals of the CT salt and had a percolation threshold of 2-3 mass% of the CT salt, as shown in Fig. 8.22. 

Estane samples were compression molded at 110°C. The blends of Estane 5703 and NP (50 50 wt ratio) or Estane/NP and Irganox 1010 (49 49 2 wt ratio) were prepared by dissolving the components in MEK to cast thin films followed by air-drying at room temperature. The films were dried in vacuo for 2 days, followed by drying at 65°C for 16 hours at ambient pressure. Samples were compression molded at 85°C into approx. I mm thick sheets and placed in aging chambers for the various studies. 

A dilute solution of a preformed polymer can be separately cast onto water, preferably from a surface active spreading solvent such as cyclohexanone. The thin film is then laminated onto a porous support layer. This approach was originally developed by Camell and Cassidy (40) and was first utilized by Cadotte and Francis in 1964 to coat microporous CA membranes. Petersen also utilized this approach to cast thin films of ethyl xellulose perfluorobutyrate which were then laminated to CelgartT and Tyvek supports for use as blood oxygenation membranes (41). 

To date, a variety of lithographic techniques, including advanced soft- and photolithographic methods, have been extensively used for constructing molecular architectures at multiple length scales [100]. Thanks to their versatility, such approaches can be easily transferred to different substrates and molecular materials, including SMMs. For instance, solution-cast thin films of... 

Kim J-S, Ho PKH, Murphy CE, Friend RH (2004) Phase separation in polyfiuorene-based conjugated polymer blends lateral and vertical analysis of blend spin-cast thin films. Macromolecules 37 2861... 

While SEC aims to separate a polymeric mixture only with respect to size (hydro-dynamic volume), investigations of substituent distribution requires a separation with respect to the chemistry of the constituents. Spurlin, very early on, recognized this problem and fiactionated cellulose nitrate by repeated dissolution and precipita-tion. The fractions obtained showed increasing viscosities and, related to this, increasing flexibihty of solution-cast thin films. Saake et al. also made use of this common principle in polysaccharide isolation, in particular the (stepwise in this instance) precipitation of CMC by ethanol from aqueous solution. ... 

J.-S. Kim, P. K. H. Ho, C. E. Murphy, R. H. Friend, Phase Separation in Polyfluorene-Based Conjugated Polymer Blends Lateral and Vertical Analysis of Blend Spin-Cast Thin Films. Macromolecules 2004,37,2861-2871. 

X-Ray Diffraction. X-ray diffractometer scans of various atactic PPBA samples are shown in Figure 7. Sample A was obtained by precipitation from CHCI3 solution directly after polymerization. Samples B and C were obtained by casting thin films from CHCI3 solution onto clean flat substrates (lead and glass). 

The graph in Fig. 3.25 shows a plot of the visible transmittance of cast thin films of Aedotron -C that were dip-coated on polycarbonate from a propylene carbonate dispersion and dried at 80°C. The sheet resistance of each film is also shown in the graph. 

By chromophore-polymer composite materials, we refer to chromophores physically incorporated (dissolved) into commercially available polymer materials such as amorphous polycarbonate (APC) [58] finm Aldrich Chemicals. Chromophore and polymer are dissolved in a suitable spin-casting solvent, such as cyclopentanone. Spin-cast thin films are heated to near the glass transition temperature of the composite material (which will vary with chromophore concentration due to the plasticizing effect of the chromophore). Acentric chromophore order is induced by electric field poling. If one assumes that the presence of the polymer host does not stericaUy hinder the reorientation of the chromophores under the influence of the poling field, the order parameter can be readily calculated. We have already noted that if chromo-phore-chromophore intermolecular electrostatic interactions are neglected then (cos d) = fiF/5kT and the order parameter will be independent of chromophore concentration (or number density, N). Intermolecular electrostatic interactions can be treated at several levels of sophistication. 

Ramon et al [17] compiled a list of commercial and prototype osmotic membranes and evaluated the resulting theoretical power densities according to their characteristics. The analysis showed that prototype lab-cast thin-film composite membranes based on a selective polyamide active layer can achieve water permeability in the range of 5-7 m/s-Pa, which result in theoretical power density in the range of 5-6 W/m with seawater feed and over 15 W/m in plant fed with I.IM brine discharged from RO-based desalinization plants. Theoretical power densities achievable with commercial membranes are below 3 W/m with seawater feed. 

It was also reported that photoinduced alignment in cast thin films of liquid crystalline polymers, of 6-[4-(4-ethylphenyl)diazenylphenyloxy]hexyl... 

Solvent solutions of polyurethane elastomers and silicone elastomers are given in Table 4.10. These materials are helpful in casting thin films and odd or complex shapes. 

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