Hydrophobe partially fluorinated

Lee HS, Roy A, Lane O, Lee M, McGrath JE. Synthesis and characterization of multiblock copolymers based on hydrophilic disulfonated poly(arylene ether sulfone) and hydrophobic partially fluorinated poly(arylene ether ketone) for fuel cell applications. J Polym Sci Part A Polym Chem 2010 48(l) 214-22. 

The above results demonstrate that partially fluorinated nonionic surfactants, having a fluorinated hydrophobic chain and a nonfluorinated poly(ethylene oxide) polar chain, can be successfully used to obtain mesoporous materials with controlled morphology and pore size. The specific surface areas can be high, similar to MCM-41 materials obtained using hydrocarbon surfactants. 

Chu et al. [166] prepared sulfonated and partially fluorinated block copolymers of high thermal stability containing 6F-BPA and perfluorobiphenylene units. Block copolymers were synthesized from the hydrophilic (29,000 g/mol) and hydrophobic parts (ll,000g/mol) with decafluorobiphenyl, the structure of which are shown in Scheme 2.37 (0 1 1 ratio for block 0, 1 9 10 raho for block 10, 3 7 10 raho for block 30, and 5 5 10 raho for block-50). The of the copolymers was in the range 15,000-90,000g/mol, with D values 1.3. 4. 

Li Y, Roy A, Badami AS, Hill M, Yang J, Dunn S, McGrath JE (2007) Synthesis and characterization of partially fluorinated hydrophobic-hydrophilic multiblock copolymers containing sulfonate groups for proton exchange membrane. J Power Sources 172 30... 

The practical applications of fluoropolymer membranes especially in the areas of purification and separation related to potable water production, wastewater treatment and bioprocessing, have been limited to some extent by their hydrophobic and inert surface properties. Among the different modification techniques, graft copolymerization of hydrophilic monomers, or inimers for further surface reactions, from fiuoropolymers has been useful and effective in improving the physicochemical properties of the parent fluoropolymer with minimum alteration of their desirable bulk properties. Apart from fiilly fluorinated polymers, most of the partially fluorinated polymers can dissolve in polar organic solvents, such as Ai,Ai-dimethylformamide (DMF), A,A-dimethylacetamide (DMAc), NMP, and dimethyl sulfoxide (DMSO), but are insoluble in water, alcohols, and hydrocarbons. 

The structure of the hydrophobe of an anionic fluorinated surfactant can be varied more extensively than the structure of the hydrophile. The hydrophobe can be a fully or partially fluorinated alkyl group having a linear or a branched alkyl chain. The hydrophobe can have an aromatic group or contain other elements (O, N, Cl, S, and Si) as well, as shown with the following examples ... 

The hydrophobes of partially fluorinated surfactants contain both fluorine and hydrogen atoms. Unlike the hydrophobe of hydrocarbon surfactants, the partially fluorinated hydrophobe consists of two mutually phobic parts which are not compatible. Partially fluorinated surfactants therefore exhibit anomalies in macroscopic characteristics, such as the critical micelle concentration (cmc), and in microscopic phenomena as well. 

The fluorinated hydrophobe can be a perfluoroalkyl group or a partially fluorinated alkyl group. Some fluorinated surfactants have hydrophobes containing... 

The same inverse gas chromatography technique was used to determine the solubility parameters of nonionic surfactants with a oxyethylene chain and a partially fluorinated hydrophobe [50]. The solubility parameter, the corrected solubility parameter, and its polar components increased with increasing polarity of the surfactants. 

The same procedure has been employed to increase the hydrophobic character of cellulose, by introducing fluorine-containing groups, e.g., 2,2-difluoroethoxy 2,2,2-trifluoroethoxy and octafluoropentoxy. Incorporation of hydrophobic moieties into cellulose is expected to increase the polymer compatibility with other materials, e.g., synthetic polymers. Note that an important part of incompatibility is due to the highly hydrophilic character of cellulose. Decreasing this character is expected to affect Tg of the derivative, as shown by cellulose propionate/octafluoropentoxy acetate (total DS = 3.0, partial DS in each moiety = 1.5), whose Tg is only 53 °C. The products are more stable than their fluorine-free counterparts, and the terminal CF2 - H group affects Tg much less than OH-substituted trifluoroethoxy celMose derivatives [196,197]. 

Polyfluorinated compounds comprise hundreds of chemicals characterized by hydrophobic linear alkyl chains partially or fully fluorinated (as the perfluorinated compounds [PFCs]) and containing different functional groups. Polyfluorinated compounds include perfluoroalkyl sulfonamides (PFASAs), fluorotelomer alcohols (FTOHs), polyfluorinated alkyl phosphates (PFAPs), fluorotelomer unsaturated carboxylic acids (FTUCAs), perfluoroalkyl acids (PFAAs), and their salts. The most common PFAAs are perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFASs). In particular, PFASs contain one or more fluorinated alkyl chains bonded to a polar head, which at neutral pH can be charged (anionic, cationic, and amphiphilic surfactants) or noncharged (nonionic surfactants). 

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