New Thermoresponsive Luminescent Electrospun Nanofibers Prepared from Poly[2,7-(9,9-dihexylfluorene)]-block-poly(N-isopropylacrylamide)/PMMA Blends

✍ Scribed by Ping Tzeng; Chi-Ching Kuo; Sung-Tso Lin; Yu-Chen Chiu; Wen-Chang Chen

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 801 KB
• Volume: 211
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.201000088

✦ Synopsis

Abstract

Novel luminescent electrospun (ES) polymer nanofibers were successfully prepared via a two‐fluid spinneret for thermo‐tunable colorimetric sensor applications. Binary blends of conjugated rod–coil poly[2,7‐(9,9‐dihexylfluorene)]‐block‐poly(N‐isopropylacrylamide) (PF‐b‐PNIPAAm)/poly(methyl methacrylate) (PMMA) were used as the material system for preparing the ES nanofibers. In order to produce uniform ES nanofibers, the shell layer was injected with THF to retard the rapid solidification of core polymer blend solutions that occurred at the nozzle tip. The prepared ES nanofibers, with an average diameter of 500 nm, exhibited a reversible photoluminescence (PL) spectra‐shifting, as the temperature cycle varied between 20 and 40 °C. Such reversible PL switching resulted from the extended/compact structural transformation on the PNIPAAm segment, which led to different PF aggregation sizes. The thermo‐responsive sensing characteristics of the prepared ES nanofibers were significantly enhanced as the PNIPAAm coil length was increased. In particular, PF~7~‐b‐PNIPAAm~516~/PMMA ES nanofibers exhibited a blue luminescence color at 20 °C but this changed to a greenish‐blue luminescence color at 40 °C. On the other hand, the corresponding spin‐coated thin film from the blend remained in the blue luminescence. Furthermore, the temperature‐responsive wettability of the surface could be switched between hydrophobicity and hydrophilicity via temperature variations. This study demonstrated that novel ES nanofibers exhibit both reversible thermo‐responsive luminescence characteristics and wettability, suggesting their potential for application as a new kind of sensory material.

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