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Updated: Apr 26, 2026

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Published on: September 9, 2022
Interfacial Inversion of Stealth Surfactants
Hong-Gyu Seong1, Pan Sun2, Jan-Michael Y Carrillo3
1Polymer Science & Engineering Department, Conte Center for Polymer Research, University of Massachusetts, Amherst, Massachusetts 01003, United States.
Core-shell bottlebrush polymers act as pH-responsive stealth surfactants. These polymers undergo structural inversion at liquid-liquid interfaces, altering their configuration to reduce interfacial tension and free energy.
Area of Science:
- Polymer Science
- Surface Chemistry
- Materials Science
Background:
- Amphiphilic macromolecular surfactants reduce interfacial tension by adsorbing at liquid-liquid interfaces.
- Core-shell bottlebrush polymers with pH-responsive diblock copolymer side chains offer tunable solubility and interfacial behavior.
Purpose of the Study:
- To investigate the interfacial behavior and surfactant properties of pH-responsive core-shell bottlebrush polymers.
- To understand the structural inversion mechanism and its influence on interfacial tension.
- To explore the design of advanced polymeric surfactants and compatibilizers.
Main Methods:
- Synthesis and characterization of core-shell bottlebrush polymers.
- Interfacial tension measurements over time.
- Sum-frequency generation vibrational spectroscopy (SFG-VS) for interfacial configuration analysis.
- Coarse-grained molecular dynamics (CGMD) simulations.
Main Results:
- Polymers exhibit a structural inversion at liquid-liquid interfaces, with hydrophilic cores moving to the aqueous phase and hydrophobic shells to the oil phase.
- Interfacial tension shows a nonmonotonic dependence on time, attributed to progressive structural inversion.
- SFG-VS confirmed pH-dependent configurational changes and interfacial coverage.
- CGMD simulations supported experimental findings, revealing time-averaged orientations of polymer components.
Conclusions:
- pH-responsive core-shell bottlebrush polymers function as effective "stealth surfactants" through a pH-induced structural inversion.
- The study elucidates the kinetics and thermodynamics of this interfacial reconfiguration.
- Findings enable the design of stimuli-responsive polymeric surfactants for diverse applications.
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