Fluorinated sulfonated polyamides

The maximum pore size used to separate phospholipid micelles, in which color pigments and other impurities are physically bound, can be in the range of 10,000-50,000 Da depending on the polymer type. Considerable swelling occurs with poly-sulfone membranes, which, in turn, affects the membrane chemistry drastically and reduces flow rates and in some cases totally closes the pores. Similar results have also been observed with polyamide and fluorinated polymers. 

A variety of polymers are used in engineering and medical applications which have relatively little impact on the environment. These are mainly high performance and relatively expensive polymers such as the silicones in rubbers, the specialised polyamides referred to above in gear wheels, polycarbonates (in office equipment), chlorinated and sulfonated rubbers, fluorinated polymers such as poly tetrafluoroethylene) Teflon ) in metal coating and the polyimides which, owing to their ladder structure, are extremely stable in high temperature apphcations. Since these polymers are high-cost durable materials, they rarely appear in the waste stream. 

To tackle the problem of fuel loss through the tank walls, polar barrier layers were tested. Among the methods tried were fluorination and sulfonation, as well as epoxy resin or polyamide powder coatings on the fuel tank walls. Again, cost and process safety were the issues begging for solutions, and fluorination and sulfonation proved to be the processes of choice for enhancing barrier properties. Both inline and offline processing approaches were tested, and fluorination with fluorine... 

Figure 4.25 Sulfonated fluorinated polyamides containing pyridine moiety [23].

Figure 4.26 Sulfonated fluorinated polyamides containing fluorene moiety [53],...

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