Fig. 2. Detailed reactions and experimental conditions of for the surfactants heads (A) and tail (B). Treatment of PFPE carboxylic acid with 3.0 equiv. (COCl)2 in refluxing HFE 7100 yields the reactive PFPE acid chloride intermediate (7). Amidation of (7) is performed in ∼3 : 1 FC 3283 : THF in the presence of 1.5 equiv. TEA with the desired amine coupling partner at RT to obtain (8, 9). During/or in preparation of the amidation reaction, reactive intermediate (7) is subject to hydrolysis reforming the parent carboxylic acid. The resultant carboxylic acid then undergoes acid–base reaction with available amines to form ammonium salts (10). Ammonium salts (10) can also undergo decarboxylation to PFPE-HEC (11) on heating.
