Related Experiment Video
Updated: Jun 7, 2026

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification
Published on: April 7, 2017
Thin but Strong Versus Thick but Soft: Contrasting Interfacial Water Barriers on Zwitterionic and Nonionic
Zhentao Zhao1, Elisa Margarita Mendoza Zamarripa1, Shigeaki Morita2
1Department of Materials Science and Engineering, School of Materials and Chemical Technology, Institute of Science Tokyo, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8502, Japan.
Abstract:
Both antibiofouling nonionic and zwitterionic self-assembled monolayers (SAMs) resist protein and cell adhesion similarly, despite having different chemical structures. This work elucidates their antibiofouling mechanisms by integrating surface force measurements with atomic force microscopy (AFM) and surface-enhanced infrared absorption (SEIRA) spectroscopy. The findings show that a very thin (<1 nm) water barrier near zwitterionic sulfobetaine (SB)-terminated SAMs causes strong short-range repulsion, whereas a thicker (>4 nm) water layer on nonionic hydroxy-terminated tri(ethylene glycol) (EG3-OH) SAMs results in long-range repulsion. SEIRA spectroscopy identified different hydrogen-bonding states in interfacial water: intense interactions with SB groups and weaker bonds with EG3-OH groups. These SEIRA insights clarify the nature of surface forces influenced by interfacial water. The study discusses how variations in hydration, SAM-water interfacial interactions, and the role of interfacial water molecules contribute to the antibiofouling effectiveness of these two SAM types.
Related Concept Videos
Intermolecular Forces
Surface Tension, Capillary Action, and Viscosity
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
Solubility
A solution is a homogeneous mixture composed of a solvent, the major component, and a solute, the minor component. The physical state of a solution—solid, liquid, or gas—is typically the same as that of the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration).
In a solution, the solute particles (molecules, atoms, and/or ions)...
Colloids
Surface Active Agents
Surface Membrane Barriers
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...

