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| Content Provider | Royal Society of Chemistry (RSC) |
|---|---|
| Author | Sakai, Ryosuke Fuchise, Keita Lin, Sung-Tso Chen, Yougen Satoh, Toshifumi Kakuchi, Toyoji Chen, Wen-Chang |
| Copyright Year | 2009 |
| Abstract | New thermoresponsive conjugated rod-coil-coil triblock copolymers were successfully synthesized from terminal azido functionalized poly(N-isopropylacrylamide)-b-poly(N-hydroxyethylacrylamide) (PNIPAAm-b-PHEAA) and alkynyl functionalized polyfluorene (PF) via a click reaction. The azido functionalized PNIPAAm-b-PHEAA copolymers with different block ratio was prepared by atom transfer radical polymerization from an initiator bearing the azide group, whereas alkynyl functionalized PF was synthesized by Suzuki coupling reaction. The lower critical solution temperature (LCST) of the block copolymers increased with an enhanced hydrophilic PHEAA block ratio, since the longer PHEAA segment facilitated the copolymer chains to stretch at an elevated temperature. The micelles of PNIPAAm-b-PHEAA with different block ratio changed into spheres, aggregate spheres, vesicles, and wormlike micelles as the temperature was increased, due to the variation on the hydrophilic/hydrophobic characteristic of PNIPAAm. However, the micellar morphologies became worms, bundles of wormlike micelles, and hollow tubes in the triblock PF-b-PNIPAAm-b-PHEAA, which were probably induced by the π–π interaction among the fluorene segments. The variation of the micelle morphology with temperature was consistent from the results of transmission electron microscopy, atomic force microscopy, and dynamic light scattering. Also, the micelle morphologies of PF-b-PNIPAAm-b-PHEAA showed a thermoreversible property based on its LCST. The photoluminescence characteristics behaved as an on/off fluorescence indicator of temperature, showing an “on-off-on” profile at an elevated temperature in water at a higher block ratio of PNIPAAm and switching to “on-off” as the block ratio of PNIPAAm decreased. The present study suggests that the PF-b-PNIPAAm-b-PHEAA copolymers have tunable morphologies and could be potentially used as thermoresponsive sensory materials. |
| Starting Page | 3761 |
| Ending Page | 3770 |
| Page Count | 10 |
| File Format | HTM / HTML PDF |
| ISSN | 1744683X |
| Volume Number | 5 |
| Issue Number | 19 |
| Journal | Soft Matter |
| DOI | 10.1039/b907764b |
| Language | English |
| Publisher | Royal Society of Chemistry |
| Access Restriction | Open |
| Subject Keyword | Atom-transfer radical-polymerization Fluorene Photoluminescence Micelle Fluorescence Hydrophobe Transmission electron microscopy Poly(N-isopropylacrylamide) Atomic-force microscopy Dynamic light scattering Suzuki Hydrophile Copolymer Azide Coupling reaction Alkyne Suzuki reaction |
| Content Type | Text |
| Resource Type | Article |
| Subject | Chemistry Condensed Matter Physics |
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