Sep 24, 2009
Nanofibres emit from blue to green
The morphology and luminescence characteristics of non-woven and aligned electrospun nanofibers have been explored using multicomponent polymer blends by researchers in Taiwan. The shape and size of the luminescent moiety can be tuned by solvent polarity, blend ratio and the degree of alignment, which gives tunable emission of colours ranging from blue to greenish-blue to green.
The aligned fibres were found to have a high polarized emission ratio. The colours emitted by the structures can be controlled by changing the emission angles. Potential applications include smart textiles, optoelectronics or nanoelectronic devices.
Making the material
Electrospinning (ES) is an attractive technique for producing various functional nanofibres because it has the advantages of low cost, enables flexible morphology tuning, and provides high-throughput continuous production. While highly aligned ES fibres based on single semiconducting polymer blends that exhibit a polarized emission ratio have been demonstrated previously, the effects of aggregated morphology on the physical properties of multicomponent semiconducting polymer blend ES non-woven and aligned fibres have not yet been explored.
Researchers at National Taiwan University are investigating the morphology and photophysical properties of non-woven and aligned ES nanofibres prepared from the ternary blends of poly(9,9-dioctylfluorenyl-2,7-diyl)(PFO) /poly(2,3-dibutoxy- 1,4-phenylene vinylene) (DB-PPV)/poly(methyl methacrylate) (PMMA) using a single-capillary spinneret and collector with a rectangular hole-gap. Their work correlates solvent polarity, (chloroform (CHCl3) and chlorobenzene (CB)), the conjugated polymer (PFO/DB-PPV) ratio, and the degree of alignment with the morphology and photophysical properties of the final structure.
In its study, the group observed various PFO and DB-PPV phase-separated morphologies in the blended ES fibres - ellipsoidal DB-PPV and central fibre-like PFO structures in the PMMA matrix using CHCl3, while fibre-like DB-PPV and fibre-like PFO structures were obtained using CB. The above different morphologies in the ES fibres resulted in a higher interchain interaction/ energy transfer using CHCl3 and various emission colours, as compared with those using CB.
Full results can be found in the journal Nanotechnology.
About the author
The work was performed at the Institute of Polymer Science and Engineering, National Taiwan University (NTU), Taiwan. Prof. Wen-Chang Chen is director of Polymer Science and Engineering and also Professor of Chemical Engineering. He has around 150 publications in peer-reviewed journals and 19 issued patents. His research interests include electronic and optoelectronic polymers, living polymerization and hybrid nanomaterials. Cheng-Ting Wang received his MS degree from NTU in 2008. Chi-Ching Kuo and Hsieh-Chih Chen both received their PhD degrees from NTU in 2009 and Chi-Ching is now a postdoc in Prof. Wen-Chang Chen’s group. In the past, all of the above students have studied the morphology, photophysical properties, and sensing application of electrospun conjugated polymer nanofibers under the supervision of Prof. Wen-Chang Chen in the Optoelectronic Polymer Group at NTU. This work was financially supported by the National Science Council of Taiwan, National Taiwan University (Excellent Research Projects), and Ministry of Economic Affairs of Taiwan.