pH and Salt Effects on Surface Activity and Self-Assembly of Copolymers Containing a Weak Polybase
Copolymers with well-defined architectures, controlled molecular weights, and narrow molar mass dispersities (Đ) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The resultant polymers contain different combinations of the pH-responsive monomer 2-(diethylam...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1992. - 32(2016), 36 vom: 13. Sept., Seite 9286-92 |
|---|---|
| 1. Verfasser: | |
| Weitere Verfasser: | , , , , , |
| Format: | Online-Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2016
|
| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | Copolymers with well-defined architectures, controlled molecular weights, and narrow molar mass dispersities (Đ) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The resultant polymers contain different combinations of the pH-responsive monomer 2-(diethylaminoethyl) methacrylate (DEAEMA), the hydrophobic comonomer butyl methacrylate (BMA), and a neutral hydrophilic stabilizing monomer polyethylene glycol monomethyl ether methacrylate (designated O950). Surface tension and cryo-TEM measurements of native and heavy-atom stained samples were used to characterize the pH and salt responsiveness of the different polymers as a function of their composition. These studies indicate that while the polymers predominately self-assemble to form spherical micelles, a narrow size distribution is observed in aqueous solutions of poly(O950)-b-(BMA) and poly(O950)-b-(DEAEMA-co-BMA), whereas a broad size distribution characterizes the assemblies of poly(O950)-b-(DEAEMA) and poly(DEAEMA-co-BMA). In the latter case, micelles having diameters around 15-25 nm are found along with smaller aggregates (about 10 nm) mostly arranged in elongated necklace-like structures. The pH and salt-responsiveness of the DEAEMA residue, as indicated by the surface activity of the copolymers, was found to depend on the nature of the additional components: covalently linked hydrophobic groups (BMA) moderated the pH response of the copolymer as compared to nonionic and hydrophilic groups as in poly(O950)-b-(DEAEMA). These results suggest that mutual interactions among the building blocks of self-assembling copolymers should be taken into account when designing responsive copolymers |
|---|---|
| Beschreibung: | Date Completed 06.06.2018 Date Revised 06.06.2018 published: Print-Electronic Citation Status PubMed-not-MEDLINE |
| ISSN: | 1520-5827 |
| DOI: | 10.1021/acs.langmuir.6b02452 |