Polymers gaseous environment, effects

Experiments involving hydrated polymers have been monitored using variable pressure SEMs (e.g., [214]), although recent evidence has shown extensive radiation damage [215, 216] occurs during these studies (see Section 5.5.2). Because the AFM can be operated in a wide range of environments, many other dynamic experiments are possible. The effect of hydration on polymer blends and membranes [135, 217] and the effect of UV irradiation in various gaseous environments on the friction of polymer films [218] are just a few examples of the himdreds of AFM dynamic studies on polymers. 

Following early ETEM investigations using environmental cells, environmental scanning electron microscopy (ESEM) has been developed for characterization of surface effects of bulk SEM samples in the presence of gaseous or wet environments (111-114). The method has been applied to the examination of food, wool fibers (111), and polymers (112) and in the conservation of cultural properties (113). Recently, fuel cell catalysts have been characterized using a low-voltage ESEM with a resolution capability of 2 nm (114). 

Cryochemically synthesized PPX films containing metal or semiconductor nanocrystals have a fine porous structure caused by features of solid-state polymerization. Due to this structure, molecules of gaseous substances readily penetrate into polymer film from the environment. Synthesized composite films demonstrate valuable strong sensor effects resulting from a marked influence of some low-molecular-weight molecules, diffusing into the polymer and adsorbed onto nanocrystals, on the film conductivity [4, 30, 62-64]. Such effects are characteristic of films whose conductivity is governed by electron transfer between nanoparticles. 

Exposure to gaseous and humid environments affects mechanical properties, friction, and wear of polymers. Synergistic effects between abrasion, wear, and corrosion result in amplified damage (59, 60). The dominant and synergistic influence of some factors may be noted as follows. 

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