Langmuir Monolayers and the Transferred Films of Fluorinated Amphiphiles Containing Vinyl Groups

Abstract

The monolayer behavior of long-chain esters of acrylic and methacrylic acids containing perfluoro or partially fluorinated carbon chains at the air/water interface was studied by surface pressure–area isotherm measurements and Brewster angle microscopy. It has been found that a minor change in the chemical structures of these fluorinated amphiphiles, such as a hydrogen substituted at the ω-position of the hydrophobic fluorocarbon tails instead of a fluorine as well as hydrophilic vinyl ester groups inserted between acrylates and methacrylates, induces a drastic change in the isotherms for the monolayers, suggesting different molecular orientation and packing in the films. The monolayers were transferred by horizontal lifting, Langmuir–Blodgett, and surface-lowering methods to give the X-, Y-, and Z-type films, respectively. These films were characterized by scanning probe microscopy, to clarify the mesoscopic surface structures of the molecular films exposed with the hydrophilic or hydrophobic moieties in air, depending upon the dipping methods. The Z-type films with the outermost surface of the fluorinated substituents were examined in relation to the frictional properties that strongly depend upon the fluorine and the hydrogen atoms at the end of the hydrophobic fluorocarbon chains, which is controllable at the atomic level.