Structure Change of Chemically Adsorbed Monolayer Having Many Kinds of Alkyl Chain Lengths

Abstract

FTIR spectra, the static contact angles, the sliding angles, and the ellipsometric thicknesses were measured on some monolayers prepared from n-alkyltrichlorosilane by a chemical adsorption (CA) technique. The molecular arrangement in the monolayer formed by the CA technique, CA monolayer, was found to be random or bulk-like when the carbon number of the alkyl group was 4 or 5, and the CA molecules were arranged along the substrate surface when the carbon number became 3, 8, and over. The arranged CA molecules were found to stand with the tilt angle of about 28° from the normal of the substrate surface when the carbon number was 8, and the tilt angle became smaller as the carbon number was above 8. It was proved that the CA molecules stood with the tilt angle of about 20 degrees when the carbon number was 20. These tilt angles were obtained by the ellipsometric thickness of the CA monolayer and the molecular length of the all trans-zigzag CA molecular model calculated by AM1.

Keywords:

• Chemical adsorption
• chlorosilane
• contact angle
• ellipsometry
• FTIR
• monolayer
• SAM
• self-assembly
• sliding angle
• surfactant