Solution cast films

The first five of these techniques involve deformation and this has to be followed by some setting operation which stabilises the new shape. In the case of polymer melt deformation this can be affected by cooling of thermoplastics and cross-linking of thermosetting plastics and similtir comments can apply to deformation in the rubbery state. Solution-cast film and fibre requires solvent evaporation (with also perhaps some chemical coagulation process). Latex suspensions can simply be dried as with emulsion paints or subjected to some... 

The release of steroids such as progesterone from films of PCL and its copolymers with lactic acid has been shown to be rapid (Fig. 10) and to exhibit the expected (time)l/2 kinetics when corrected for the contribution of an aqueous boundary layer (68). The kinetics were consistent with phase separation of the steroid in the polymer and a Fickian diffusion process. The release rates, reflecting the permeability coefficient, depended on the method of film preparation and were greater with compression molded films than solution cast films. In vivo release rates from films implanted in rabbits was very rapid, being essentially identical to the rate of excretion of a bolus injection of progesterone, i. e., the rate of excretion rather than the rate of release from the polymer was rate determining. 

Spectra of solution cast films of the hydrogenated NBR were recorded on a Nicolet 520 FT-IR spectrophotometer. The final degree of olefin conversion was confirmed by infrared analysis.9... 

SEM micrographs of two members of these polymers (HB and HBIB-50) are shown in Figure 7 to provide further evidence for superstructure on the micron level within the solution cast films. One can directly observe the surface of the spherulitic structure of the HB homopolymer as well as in that of the copolymer HBIB-50. Clearly, the level of structure (-5 pm) is well above that of the individual domains of either HB or HI and reflects the possible primary nucleation and subsequent growth behavior common to spherulitic semicrystalline polymers. The Hv patterns shown in... 

A comparison of the dynamic mechanical properties of our HB at 35 Hz has been made to that of LDPE in Figures 14 A and B. The thermal and sample preparative history affects the mechanical properties of HB films to such an extent that in order to make a meaningful comparison one has to describe the exact history of the samples. Such a thermal history dependence has been examined for LDPE(54,57) and recently for HB.(12) Shown in Figures A and B are the mechanical spectra for HB-PQ, HB-Tol, and LDPE-PQ films. The compression molded films were prepared 1 to 2 days prior to the test. The solution cast film (from toluene), HB-Tol, was annealed at 80°C for 2-3 days and stored at room temperature for 1 week... 

Solution-cast films of polyaniline optical quality transparent electrodes... 

Y Cao, GM Treacy, P Smith, and AJ Heeger, Solution-cast films of polyaniline optical-quality transparent electrodes, Appl. Phys. Lett., 60 2711-2713, 1992. 

Fig. 6 Electron time-of-flight photocurrent transients of solution-cast film of EHO-OPPE (L=8 pm), measured at 295 K and an electric field of 2.5-10 V cm in (a) linear and (b) double logarithmic plots. Reproduced with permission from [61]...

Fig. 7 Room temperature FET-mobility of P3HT in different microstructures. Downward triangles, spin-coated regioregular film, upward triangles, solution cast film. From [83] with permission. Copyright (1999) by Macmillan Publishers...

Solution-cast film is produced on a larger scale for medical applications, battery separators, or other specialty uses with machinery of the type shown in Figure 3.2 [2], Viscous film is made by this technique. The solution is cast onto the surface of a rotating drum or a continuous polished stainless steel belt. These machines are generally enclosed to control water vapor pickup by the film as it dries and to minimize solvent vapor losses to the atmosphere. 

Figure 3.2 Machinery used to make solution-cast film on a commercial scale...

The first successful application of this method was reported by Mullen and coworkers [18]. The removal of their solubilizing group occurs thermally at temperatures as low as 180 °C, yielding pentacene and a volatile tetrahalobenzene. The tetrachloro compound 4 (Fig. 3.3) formed good-quality films from spin-cast solution, and heating the film of the soluble precursor at 200 °C for 5 s yielded the desired acene film. FET properties for devices made from solution-cast films were quite good - measured mobilities were as high as 0.2 cm2 V-1 s-1 with on/off current ratios of 106. 

In the case of solution-crystallized UHMW-PE, it is possible to make solution-cast films in which the lamellar crystals are regularly stacked,... 

Fig.8 (a) Electron micrograph and (b) schematic representation for the regular lamellar structures formed within solution-cast films of UHMW-PE... 

A well-defined amount of co-crystallization is possible across the interface of two adjacent crystals by annealing two stacked, completely wetted, solution-cast films of UHMW-PE [32]. It was found that doubling of the lamellae across the interface enhances the peel energy to such a level that the films could not be separated anymore. By contrast, pre-annealing one side of the film prohibited co-crystallization across the interface and these films could still be separated easily. It was therefore concluded that a limited amount of chain diffusion across the interface occurs during doubling of the lamellae, as facilitated by the well-defined structure of the interphase due to the adjacent reentry that occurs upon crystallization from solution. 

Fig. 7. Miscibility door for 50/50 blends of PB and SB as a function of copolymer composition. The circles refer to experimentally determined LCSTs and UCSTs. The curve was calculated using the equation-of-state theory discussed in Sect. 2.1. Miscibility occurs to the left of the curve. Inside the dashed area, solution cast films are transparent [39]...

Electron diffraction of solution cast films annealed at 52°C (which is just below the melting point of PCL homopolymer) shows soft-segment... 

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