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Interfacial water

Interfacial water and ice at organic and biological surfaces

This is a fundamental research project concerning the structure, phase behaviour and morphology of ultrathin water layers on model organic and biological surfaces. A large part of the work is performed at low pressures and temperatures, meaning that we are talking about thin ice layers. SAMs are used to generate model surfaces with different properties, e.g., controlled wettability, charge polarity etc.. The analytical tools used to characterize these thin layers of ice are FT-IR spectroscopy and temperature programmed desorption (TPD) in UHV. We are especially interested in finding collelations between the macro(liquid drops)- and microscopic(ice clusters) wetting behaviour of such surfaces. Theoretical work aiming at improving the understanding of IR spectra of ice i performed in collabortaion with Prof. D.L. Allara at Penn State University, USA. So far, the model experiments have been performed on relatively simple SAMs, but more complex ones bearing polyethylene-glycol and saccharide entities are currently investigated. We have recently also initiated a biomimetic project on anti-freeze surfaces and materials. Winter flounder is a flat fish living in the arctic oceans. A protein referred to as AFP (anti-freeze polypeptides) showing antifreeze activity has been isolated in serum of this flo under. This protein consists of a repetitive structure, a 37-mer, which has been identified as the critical domain leading to a lowering of the freezing point (about 1-2 ?C). The 37-mer is generated from a repeating alanine-rich 11-amino acid unit where threonines are separated in a well-defined manner. One model used to explain the antifreeze activity, the “ice binding model”, postulates that the distribution of threonines forms a unique hydrogen bonding pattern with the ice surface preventing further nucleation and growth. Others claim that substitution of the threonines with other amino acids, also result in a lowering of the freezing point. Thus, the role of hydrogen bonding is not clear. Another type of heavily glycosylated polypeptides, AFGP’s, also exhibits antifreeze activity. This polypeptide is composed of an (Ala-Ala-Thr) repeating tripeptide unit, where a disaccharide is linked to the threonine OH residue. The disaccharide residues form a hydrophilic domain (face) that can interact (hydrogen bond) with the ice surface. We are developing two different strategies for the preparation of prototype anti-freeze surfaces:
  • a minimum sequence approach to investigate the possibilility of using the 37-mer, or smaller segments thereof, as building blocks for anti-freeze surfaces.

  • self-assembled monolayers of w-substituted alkanethiols bearing amide linked residues like -CH3 to mimic alanine and -CHCH3OH to mimic threonine will be assembled on gold substrates


During recent years, an increasing number of studies have been dealing with the potential applications of self-assembled monolayers (SAMs), in such diverse areas as molecular recognition, surface biology and biochemistry, chemical force microscopy, metallization of organic materials, corrosion protection, molecular crystal growth, alignment of liquid crystals, pH-sensing devices, patterned surfaces on the µm scale, and lithographic resists. In several of these areas, a fundamental understanding of the interaction between SAMs and secondary adsorbates is crucial. For example, in biochemical applications where water-organic interfaces are ubiquitous and in studies of the molecular basis of wetting and of hydrogen bonding interactions, the importance of water as the secondary adsorbate cannot be overestimated. As a matter of further interest, the formation, ordering, and phase behavior of interface-confined solid water films, i.e., ice, constitute a research topic in its own right, with possible applications in astrophysical research, biochemistry, and in the fundamental understanding of liquid water. For these reasons, we are performing a series of model experiments to systematically evaluate the interactions of water with a large set of SAMs of single and mixed chemical functionalities.


The SAMs are mounted in a UHV system where they are cooled, dosed with water (D2O in most cases) and then examined with IRAS and TPD. Typically, water doses yielding a 1-10 Å overlayer (average thickness) are used. Some of the SAM functionalities that have been or currently are being investigated are:

  • -CH3

  • -OH

  • -(C=O)OCH3

  • -O(C=O)CH3

  • -O(C=O)CF3

  • -O(C=O)C6H5

  • mixtures of -CH3 and -OH

  • different kinds of gradient samples


Results of these investigations can be found in the following papers.

"Temperature-Programmed Desorption and Infrared Studies of D2O Ice on Self-Assembled Alkanethiolate Monlayers: Influence of Substrate Wettability"
Isak Engquist, Ingemar Lundström and Bo Liedberg
J. Phys. Chem. 99 (1995) p. 12257

"Hydrogen Bond Interaction between Self-Assembled Monolayers and Adsorbed Water Molecules and Its Implications for Cluster Formation"
Isak Engquist, Magnus Lestelius and Bo Liedberg
J. Phys. Chem. 99 (1995) p. 14198

"Infrared Characterization of Amorphous and Polycrystalline D2O Ice on Controlled Wettability Self-Assembled Alkanethiolate Monolayers"
Isak Engquist, Atul N. Parikh, David L. Allara, Ingemar Lundstršm and Bo Liedberg
J. Chem. Phys., accepted for publication

"D2O Ice on Controlled Wettability Self-Assembled Alkanethiolate Monolayers: Cluster Formation and Substrate-Adsorbate Interaction"
Isak Engquist and Bo Liedberg
J. Phys. Chem. 100 (1996) p. 20089

Responsible for this page: Erik Martinsson
Last updated: 05/16/06