A Structural X-ray Study on Semifluorinated Alkanes (SFA):  SFA Revisited

Abstract

We present an X-ray scattering study on a series of semifluorinated n-alkane (F12Hn) powder samples, with even-numbered hydrocarbon chains n ) 6-18. At elevated temperatures the samples appear to have a simple lamellar structure consisting of single-layered stacks. At ambient temperature three different rather complex bulk structures were observed as a function of the chain length of the hydrocarbon molecular moiety. Our results are compared to structure models for F12Hn found in the literature, and some new features of the structure of the room temperature phase are disclosed.

Semifluorinated chains in 2D-(perfluorododecyl)-alkanes at the air/water interface

“…Compounds with the general formula F(CF 2 ) 12 (CH 2 ) m H, where m = 6, [8][9][10][11][12][13][14][15][16]18, and 20, were synthesized following a procedure described elsewhere [5]. Perfluorododecyl iodide was supplied by Exfluor (USA) and purified by vacuum sublimation prior to use.…”

“…Despite numerous options for molecular structure and composition, the most investigated SFAs are those with long perfluorinated chains. They were characterized in solid state [8][9][10][11], in solutions [12][13][14][15][16], and as Langmuir monolayers [17][18][19].…”

SAFT-γ force field for the simulation of molecular fluids: 8. Hetero-segmented coarse-grained models of perfluoroalkylalkanes assessed with new vapour–liquid interfacial tension data

“…PFAA molecules are known to aggregate in solvents with a propensity for one of the chain segments [2,3], and to form smectic (layered) liquid-crystalline phases [4][5][6], as well as molecular films displaying surprising patterns at the nanometric scale [7,8]. Organisation into layered structures in the solid state and surface freezing has also been described [9][10][11][12][13][14].…”

Perfluoroalkanes and perfluoroalkylalkane surfactants in solution: Partial molar volumes in n-octane and hetero-SAFT-VR modelling

“…Aggregation of PFAA in solvents selective for one of the chains [1,2], the observation of smectic liquid crystalline phases [3][4][5], and the formation of nanoscale patterns in molecular films of either pure [6] or mixed perfluoroalkylalkanes have all been reported [7]. Organization in the solid state into layered structures has also been described [8][9][10][11].…”