Messungen zum Aggregationsverhalten perfluorierter Alkansäuren

Abstract

With the use of various techniques an attempt was made to characterize the aggregates that exist in micellar surfactant solutions of salts of the perfluornonanoic acid. The cmc values of the investigated systems were determined by conductivity and surface tension measurements. Conclusions about the shape of the micellar aggregates were drawn from rheologic and electric birefringence measurements. For the lithium, the ammonium and the tetramethylammonium surfactants the existence of normal micelles with spherical shape and with all surfactant ions lying at the micellar surface was found. The perfluornonanoate surfactants with the ammonium counterions that are partially substituted by alkyl groups showed in all investigations a behaviour that was different from the normal case. It was postulated that these solutions contain emulsion-droplet-like giant micelles with the surfactant ions and counterions solubilized as ion pairs in the interior of the micelles. Some of these giant micelles d o not have spherical shape; these solutions showed electric birefringence. In most cases the giant micelles disappeared at higher temperatures. Only normal small micelles with spherical symmetry could then be detected and the measured values were again in, the range for values of normal C8-perfluordetergents. On the basis of the investigated systems reasons and models for the formation of giant micelles are discussed.

Molecular Orientation and Morphology of Organized Molecular Films for Fluorinated Comb Copolymers

“…These polymers form the layer structure along the direction of c-axis. According to the previous work, it seems that this long spacing peak in the profile of Poly-FF 10 EMA were defined at (002) reflection, [30] because Poly-FF 10 EMA form the double layer structure, and also because the calculated length of fluorocarbon sidechain are estimated about 21 Å . The d-spacing from (001) reflection peak of Poly-OMA was estimated at 30.3 Å .…”

“…Figure 5 displays 2 nd -heating processes of DSC thermograms for each homopolymer and copolymers. On going from Poly-OMA to FF 10 EMA:OMA ¼ 1:1 copolymer, the peak positions in the low temperature side hardly move with a variation in FF 10 EMA ratios. In the case of peaks in the high temperature side, those don't shifted with OMA ratios except the one of FF 10 EMA:OMA ¼ 1:1 and 1:2 copolymers, although these peaks sprit within the region of 90-130 8C, which mean the existence of different thickness of 'lamellae' (in this case, this term is able to exchange to the 'layers').…”

“…Plots of fusion enthalpy of side-chain crystals vs. FF 10 EMA ratio in fluorinated comb copolymers estimated from DSC thermograms. fluorinated region is corresponding to the expand phase, and hydrogenated region is condensed phase with highly order molecular orientation.…”

“…Plots of peak top and on set temperature vs. FF 10 EMA ratio in fluorinated comb copolymers estimated from DSC thermograms.…”

“…For the last quarter of a century, fluorinated functional materials have been synthesized to compare with corresponding hydrocarbon derivatives. [5][6][7][8][9][10] Surfactants with fluorocarbons in solutions are known to exhibit different behaviors from those of the corresponding amphiphiles with hydrocarbons. [11] Fluorinated amphiphiles and polymerizable lipids were synthesized for formation of biomembrane models.…”