Fluoropolymer membranes physical properties

Surface modification of the polymeric membranes via molecular design is one of the most versatile means to improve the surface properties without affecting bulk properties. Surface modification of fluoropolymer membranes, especially for fully fluorinated polymer membranes, such as PTFE membranes, has been of particular interest, due to their physical and chemical inertness. Surface modification of fluoropolymer membranes can be classified into two categories surface coating and surface grafting. 

Due to their physical and chemical inertness, fluoropolymers are resistant to UV irradiation in the wavelength range of 100-400 nm. It is difficult to directly activate the fluoropolymer membrane surface via UV initiation due to its inert property. A photo-initiator, such as benzophenon, is usually needed to initiate the photo graft polymerization process from the fluoropolymer membrane surfaces [130]. Benzophenon was decomposed into radicals. The free radicals are transferred to the fluoropolymer membrane and hydrogen abstraction leads to the generation of initiating radicals. Benzophenon can be coated onto the membrane surface by dipping the membrane in benzophenon solution in an adsorption process [130,131]. This method could... 

Like many other fluoropolymers, Nafion is quite resistant to chemical attack, but the presence of its strong perfluorosulfonic acid groups imparts many of its desirable properties as a proton exchange membrane. Fine dispersions (sometimes incorrectly called solutions) can be generated with alcohol/water treatments. Such dispersions are often critical for the generation of the catalyst electrode structure and the MEAs. Films prepared by simply drying these dispersions are often called recast Nafion, and it is often not realized that its morphology and physical behavior are much different from those of the extruded, more crystalline form. 

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