Hybrid surfactants containing separate hydrocarbon and fluorocarbon chains

Abstract

Two homologous series of double-tail hybrid surfactants containing a hydrocarbon chain and a fluorocarbon chain attached to the same hydrophilic head group have been synthesized. The micellar solutions of such hybrid surfactants have been studied by conductance, surface tension, 19F NMR and 'H NMR. The dependence of the cmc on the chain length follows Klcven's equation. The micellar aggregation numbers are 10-35 and become smaller as the chain length increases. When the hydrocarbon chain bears three carbons or more, both the fluorocarbon and the hydrocarbon chains are incorporated inside the micelle. IntroductionThere has been a continuous effort in industry to prepare new formulations of detergents by changing the compositions of the surfactants, builders, and additives. However, there is relatively little development in the synthesis and characterization of new surfactants that have unusual structures, properties, and applications. The hybrid surfactants described in this paper represent part of our effort in this direction. They are composed of a hydrocarbon (HC) chain and a fluorocarbon (FC) chain attached to the same hydrophilic head group and are a new category of compounds which have not been explored previously.Doubletail surfactants with two HC chains attached to a sulfate head group have been studied by Winsorl and Evans2 in the 1950s. These homologous compounds of sodium dialkyl sulfate have the structural formulae RR'CHOS03Na, in which R and R' are unbranched HC chains with R having a longer chain length than R'. The hybrid surfactants reported here have similar structures, except that one of the chains is an unbranched FC chain.It has long been noticed that fluorinated surfactants are particularly efficient in lowering surface tension. Normally, in the mixture of a FC surfactant with a suitable HC surfactant, the FC surfactant reduces the surface tension while the HC surfactant aids in the reduction of the interfacial tension. The net result can be a system that easily wets and spreads on otherwise hard-tewet ~urfaces.~ However, for ionic surfactants with the same headgroup charge, the application of this advantage of combined effect is limited because of the demixing of HC/FC mixed surfactants. To overcome this problem, some single-chain surfactants containing a FC segment and a HC segment were synthesized, and they show good wettability on solid substrates containing FC ~omponents.~ Recently, Abenin and Cambon reported the synthesis of a series of double-tail HC/FC surfactants R&&NHCH2CHOHCH2NRI "Rm5 Such surfactants are very effective in lowering the surface tension or interfacial ten~ion.~ To our knowledge, hybrid surfactants containing separate FC and HC chains attached to the same head group have not been reported. In the present work, the synthesis, characterization, and the micellar properties of a homologous series of novel double-tail hybrid surfactant are described:

Design and synthesis of a two compartment micellar system based on the self-association behavior of poly(N-acylethyleneimine) end-capped with a fluorocarbon and a hydrocarbon chain

“…The incompatibility is determined by the length of the two end groups and by the interaction energy of water with CF 2 and CH 2 groups. Experimentally a is determined for one CF 2 group to be 1.5 kT 47,48) and 1.1 kT for one CH 2 group 44) . This results in a volume fraction of U Gel = 0.058.…”

Fluorinated and semi-fluorinated surfactants

“…The increased unfavourableness of micelle formation is a result of a combination of the unfavourable energy of mixing of hydrocar- A series of hybrid surfactants of general structure F(CF 2)n'-CHS04Na. (CH2)mH (abbreviated to FnS04Hm) has been investigated by Guo et al [60]. The corresponding series of hydrocarbon surfactants (HnS04Hm) has been studied by Evans [61].…”

Synthesis and Solution Properties of Sulfate-Type Hybrid Surfactants with an Ethylene Spacer

“…It is known in NMR that if a nucleus is in a more polarized environment, the shielding effect on it is generally reduced to make the chemical shift larger (17), and the effect tends to increase in the order, fluorocarbon water hydrocarbon (5,18). When the CH 3 group of a monomeric hydrocarbon surfactant molecule in an aqueous environment is transferred into the micellar hydrocarbonaceous environment of the surfactant, the shielding effect of the group is reduced and the chemical shift is increased.…”