Related Experiment Video
Updated: May 8, 2026

Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy
Published on: July 18, 2014
Chunks of charge: effects at play in the assembly of macromolecules at fluid surfaces
Ellen J Robertson1, Geraldine L Richmond
1Department of Chemistry, University of Oregon, Eugene, Oregon 97403, USA.
Abstract:
Large macromolecules with hydrophobic backbones are known to assemble at the interface between immiscible liquids. This assembly is often unpredictable because of the subtle interplay among hydrophobic interactions, hydrophilic solvation, structural constraints, and the thermodynamics of adsorption. In these studies, we employ vibrational sum frequency spectroscopy and interfacial tension measurements to study the assembly of a simple polyelectrolyte, poly(methacrylic acid), as it assembles at the interface between two immiscible liquids, specifically, carbon tetrachloride and water. By adjusting the polyelectrolyte charge through pH studies and the polymer size through molecular weight studies, we demonstrate that charge accumulation in segments of the polymer chains is a critical factor in macromolecular interfacial adsorption and desorption. The results have implications for related charged macromolecules whose ability to assemble between two immiscible fluid media is essential for many biological processes, water remediation efforts, and enhanced oil recovery.
Related Concept Videos
Continuous Charge Distributions
The electric charge can also be subjected to an analogical...
The Electrical Double Layer
Micelles
Surface Tension of Fluid
Surface tension varies with...
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...
The Fluid Mosaic Model

