Interfacial reactivity of block copolymers : understanding the amphiphile-to-hydrophile transition
Block copolymers offer an interesting platform to study chemically triggered transitions in self-assembled structures. We have previously reported the oxidative degradation of vesicles made of poly(propylene sulfide)-poly(ethylene glycol) (PPS-PEG) copolymers. Here we propose a mechanism for vesicle...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 21(2005), 20 vom: 27. Sept., Seite 9149-53 |
|---|---|
| 1. Verfasser: | |
| Weitere Verfasser: | , |
| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2005
|
| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Biocompatible Materials Membranes, Artificial Polymers Polypropylenes Sulfhydryl Compounds Water 059QF0KO0R Polyethylene Glycols |
| Zusammenfassung: | Block copolymers offer an interesting platform to study chemically triggered transitions in self-assembled structures. We have previously reported the oxidative degradation of vesicles made of poly(propylene sulfide)-poly(ethylene glycol) (PPS-PEG) copolymers. Here we propose a mechanism for vesicle degradation deduced from copolymer conformational changes occurring at the air/water interface in a Langmuir trough together with a reactive subphase. The hydrophobic PPS block is converted into hydrophilic poly(propylene sulfoxide) and poly(propylene sulfone) by oxidation upon exposure to 1% aqueous H(2)O(2) subphase. As a result, a dramatic increase in area per molecule at constant surface pressure (Pi) was observed, followed by an apparent decrease (recorded as decrease in area at constant Pi) due to copolymer dissolution. For monolayers at the air/water surface, the large interfacial tensions present suppress increases in local curvature for alleviating the increased hydrophilicity of the copolymer chains. By contrast, vesicles can potentially rearrange molecules in their bilayers to accommodate a changing hydrophilic-lipophilic balance (HLB). Similar time scales for monolayer rearrangement and vesicle degradation imply a common copolymer chain solubilization mechanism, which in vesicles lead to an eventual transition to aggregates of higher curvature, such as cylindrical and spherical micelles. Subtle differences in response to the applied surface pressure for the diblock compared to the triblock suggest an effect of the different chain mobility |
|---|---|
| Beschreibung: | Date Completed 17.04.2007 Date Revised 01.12.2018 published: Print Citation Status MEDLINE |
| ISSN: | 1520-5827 |