Fluorocarbon-modified water-soluble cellulose derivatives

Abstract

dihydroperfluorooctyl, and octyl derivatives of (hydroxyethyl)cellulose (HEC) were prepared by reaction of the Na salt of HEC in aqueous isopropyl alcohol with 1,1dihydroperfluorobutyl or octyl p-toluenesulfonate (4 or 5), with 1,1-dihydroperfluorobutyl or octyl glycidyl ether or (8 or 9), and with octyl glycidyl ether (12). The degrees of substitution of HEC were determined using 19F NMR and varied between 0.023 and 1.20 mol % of anhydroglucose units (AGU). The HEC derivatives modified with 4,5, and 8 were sparingly soluble or insoluble, and their aqueous solutions were generally low in viscosity. In contrast solutions of HEC modified with 9 did have significantly enhanced viscosities with respect to unmodified HEC or compared to HEC modified with the octyl glycidyl ether, having the same chain length as 9. The Brookfield viscosity plotted against perfluorocarbon content of aqueous solutions of HEC modified with 9 was shown to go through a maximum at about 0.42 mol % (0.92 wt %) with respect to AGU's. The solutions of this and similar polymers were shown to be highly pseudoplastic. Furthermore, increases in viscosity were observed upon addition to NaCl. These observations are consistent with the very strong intermolecular hydrophobic association of the perfluorocarbon groups.

Polysoaps with fluorocarbon hydrophobic chains

“…Still, it is evident that the hydrophobized copolymer series 3a-3c and 4b-4c exhibit substantially lower t] ni values than poly-1 There is no indication of thickening effects as observed fo watersoluble copolymers with a very small fluorocarbon hydrophobe content [5][6][7][8][9][10][11]25]. Though effects due to strongly differing degrees of polymerization cannot be rigorously excluded as the molar masses are unknown, they are highly improbable as the polymerization conditions for the polymers were virtually identical.…”

“…In particular, the use of fluorocarbon hydrophobic chains in polymers has so far been very limited. The few studies have been restricted basically to water-soluble polymers which are weakly substituted with fluorocarbon chains to provide efficient thickeners [5][6][7][8][9][10], or to block copolymers [11][12][13][14][15] or oligomers [16,17] respectively. Examples for water-soluble polymers which are heavily substituted with fluorocarbon chains, as needed for polysoaps to enable intramolecular aggregation, are virtually missing.…”

Molecular concepts, self-organisation and properties of polysoaps

“…Viscosity studies on perfluoroctyl substituted hydroxyethyl cellulose suggest that the CAC values are considerably lower for fluorocarbons than for hydrocarbons [297]. The lower CAC values can be explained by the increased hydrophobicity of fluorocarbon tails.…”

“…This borderline is very important, as slightly hydrophobized water-soluble polymers are known to aggregate mtermolecularly thus acting e.g. as thickeners [77,151,162,218,222,285,[294][295][296][297], whereas even lesser hydrophobized polymers do not aggregate at all. This is in contrast to the intramolecular aggregation of polysoaps producing solutions of very low viscosity (see Sects.…”

19F-nuclear magnetic resonance spectroscopy as a tool to investigate host-guest complexation of some antidepressant drugs with natural and modified cyclodextrins

“…Fluorine ( 19 F) NMR has been used to demonstrate the complexation of natural β-CD with perfluorinated ends of telomeric polymers [9][10][11] and fluorinated amino acid derivatives [12]. Fluorine as a group is rare in natural compounds, but is a relatively common substitute in drugs.…”