Spontaneous adsorption on a hydrophobic surface governed by hydrogen bonding

Langmuir. 2009 Aug 18;25(16):9296-301. doi: 10.1021/la900850u.

Abstract

Spontaneous adsorption from solution onto solid surface is a common phenomenon in nature, but the force that governs adsorption is still a matter of considerable debate. (1, 2) We found that surfactants and cellulose adsorb from solution onto a poly(methyl methacrylate) (PMMA) surface in an ordered and cooperative way governed by hydrogen bonding. The glucose rings of n-dodecyl-beta-D-maltoside (DDM) and hydroxyethylcellulose (HEC) stand perpendicular to the surface, H-bond to the surface COOMe groups with their C=O and Me-O bonds parallel to the surface, and form a tight monolayer. The non-H-bonded COOMe groups orient their C=O bonds perpendicular to the surface. In contrast, the glucose rings of hydrophobically modified hydroxyethylcellulose (HMHEC) lie flat with the side chains perpendicular to the surface and H-bond to the perpendicular-oriented C=O groups. The non-H-bonded COOMe groups orient their C=O bonds parallel but Me-O bonds near-perpendicular to the surface for stabilizing HMHEC. The current work provides a detailed picture of how surface-active molecules interact with a solid surface and self-assemble into greatly different architectures.

MeSH terms

  • Adsorption
  • Carbohydrate Sequence
  • Cellulose / analogs & derivatives
  • Cellulose / chemistry*
  • Glucosides / chemistry
  • Hydrogen Bonding
  • Hydrophobic and Hydrophilic Interactions*
  • Microscopy, Atomic Force
  • Molecular Sequence Data
  • Molecular Structure
  • Polymethyl Methacrylate / chemistry*
  • Surface-Active Agents / chemistry*

Substances

  • Glucosides
  • Surface-Active Agents
  • dodecyl maltoside
  • Cellulose
  • hydroxyethylcellulose
  • Polymethyl Methacrylate