Spin-cast specimens

Figure 1. Cyclic tensile stress-strain behavior of the spin-cast specimens, TR-41-1647, TR-41-1648, and TR-41-1649, at 25°C at a constant rate of tensile train, 50% /min. The tensile stress is expressed in terms of true stress. The specimens were air dried...

Figure 3. Electron micrographs of ultrathin sections of film specimens spin-cast from 10% solutions of a series of tri-block copolymers (a) TR-41-1647, (b) TR-41-1648, and (c) TR-41-1649, all in a mixture of THF and methylethyl-ketone in volume ratio of 90/10 and stained by OsOA...

Sample preparation In order to measure the interfacial thickness, always bilayer specimens were prepared containing a thick substrate (about 1mm) and a thin film on top (in the range from 15 to 100 nm). The substrates were melt-pressed between two silicon wafers at 200 °C. The thin films were prepared by spin-casting of the polymer solutions onto a silicon wafer and the resulting films were floated off onto a water surface. The floating films were then picked up with the substrate and dried at elevated temperatures in a vacuum oven. 

Figs. 5 and 6 show electron micrographs of ultrathin sections of film specimens of an SBS block copolymer and its blend with PS. The average molecular weights of the SBS and PS are 14-30-14 and 20.4 in units of thousands. The film specimens were spin-cast from 10% solutions of SBS and its blend with 20% PS in a mixed solvent of tetrahydrofuran and methyl ethyl keton (90/10 by volume). As can be seen in the figures, both specimens have alternating lamellar domains of the two components, oriented randomly. The styrene lamellae of the SBS-PS blend specimen are found to be thicker than those of the SBS specimen, due to solubilization of the PS into styrene lamellar domains of the SBS. 

The present discussion [47] deals with the formation of natural self-assembly of CuS nanoclusters in dielectric substrates of gum Arabica biopolymer. Low concentration of ammonium complex of copper oxide solution was dissolved in gum Acacia Arabica solution at 60°C and stirred. H2S gas was passed in the same environment for 1 minute. Heating the resulting solution to about 100°C evaporates any possible trace of ammonia. The resulting nanocomplex was caste in the form of very thin film by spin coating technique. The developed specimen was used for experimental investigations, namely TEM, XRD, and electrical experiments such as impedance spectroscopy, and the Arrhenius plot and I-V characteristics were measured in the applied field direction perpendicular to the 2-D plane. 

The free surfaces of samples are studied using SEM and AFM. The smooth specimen surfaces which are required for this purpose are prepared either by ultramicrotomy or by solution-casting procedures (e.g., spin-coating). The free surface can also be etched by reactive ions via a process known as reactive ion etching (RIE) [49-51], or by using chemicals as in the case of permanganic etching [52-55]. 

Thick (1-2 mm) and thin (100 nm) film specimens were prepared by solvent casting and spin-coating of particle bmsh solutions followed by thermal annealing in vacuum above the softening temperature of the polymer. Figure 10 depicts the results of both microstmctural characterization and mechanical deformation of the sparse bmsh nanocomposite film samples. 

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