Polymer Science 1 Film-Forming Materials

For TG work it is generally recommended to use as little sample as possible within the limits of resolution of the microbalance. The homogeneity of a sample can sometimes limit how little sample can be used, e.g., in case of polymeric materials. Powdered samples, of small particulate size, have the ideal form for TG studies. However, in polymer science, samples are often also in the form of films, fibres, sheets, pellets, granules or blocks. The packing density should be as uniform as possible. 

Not all membrane materials can be made into a thin selective layer on a porous substrate in a hollow fiber form. Consequently, spiral-wound membranes, which can be made from a wider range of materials, usually have higher permeation rates. However, this is offset by the much higher packing density of hollow fiber modules, resulting in similar overall productivity per unit module volume for the two configurations. This situation could change if developments in polymer science lead to more effective thin films in a hollow fiber form. 

The stability of thin liquid films on solid surfaces is a major topic both in fundamental and in applied science. In flotation, the aqueous film formed between a particle and an approaching bubble determines the interaction and thus the efficiency of the process [695, 753, 813, 814]. Polymer films preserve, isolate, or decorate materials [815-820]. Thin metal films in microelectronics serve as electrodes [821-823]. When such films dewet, a solid surface complex pattern is formed (Figure 7.15) [824]. 

Polymer chemistry and technology form one of the major areas of molecular and materials science. This field impinges on nearly every aspect of modem life, from electronics technology, to medicine, to the wide range of fibers, films, elastomers, and structural materials on which everyone depends. 

In this electronic age, it is mandatory to use solid polymer electrolytes for different applications in science and technology. Polymer electrolytes can be shaped in the form of thin film, thereby reducing the internal resistance leading to application as gas sensing material. Few reports appeared on proton-conducting polymer films and their application to gas sensors [65]. 

The obtained patterned polymer surfaces can also be replicated by metal thermal evaporation to produce nanostructured metallic films with holes or asperities of controlled size, as illustrated in Fig. 11.10. After deposition of a sufficiently thick metal layer, the polymer layer can be cleaved or dissolved away. This procedure allows an efficient and precise control of the metallic surface structure, with possible applications in materials science and photonics. The roughness of polydimethylsiloxane (PDMS) surfaces can be tuned by this technique if the PDMS is treated while cross-linking, which may be of interest for microfluidic applications. We have also observed that substrates of poly(methyl methacrylate) (PMMA), PS in the form of colloidal spheres and bulk, and semiciystalline films of polyethylene (PE) are prrMie to be structured by this technique, evidencing the versatility and potential for its widespread use. It may find applications in many different scientific and technological fields like nanoUthography, microfluidics, or flexible electronics. 

The technology of membrane separations is a new and growing field where the polymer membrane contributes unique separation properties based on its structure and, to some extent, on its chemical composition. Various manufacturing processes are used to create special structures in forms such as flat films and hollow fibers. Lonsdale [143] provides a review of the history and current status of separation media and their applications, and a text [144] provides a discussion of the materials science of synthetic membranes. 

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