Abstract
A short-range-ordered, soft glassy colloidal array (SGCA) exhibits angle-independent and non-iridescent structural color. To control the angle-independent structural color using external stimuli, a thermosensitive SGCA composed of block copolymer, poly(benzyl methacrylate)-block-poly(methyl methacrylate) (PBnMA-b-PMMA), grafted silica nanoparticles was prepared in an ionic liquid. The thermosensitive properties were studied over a wide range of particle concentrations and temperatures. In the dilute suspension, the outer PBnMA blocks shrunk at high temperatures because of their lower critical solution temperature behavior, whereas the inner PMMA blocks gave rise to steric repulsion, stabilizing the particles against aggregation even at the high temperatures. A blue shift of the reflection peak with increasing temperature was observed for the glassy arrays at semidilute particle concentrations; however, an opposite red shift was observed at high particle concentrations. This unexpected red shift in the highly concentrated suspension was interpreted as swelling of the inner PMMA blocks associated with the desolvation and segregation of thermosensitive PBnMA blocks in the outermost region of the particles. This temperature-sensitive continuous shift of the reflection peak demonstrates the potential application of thermosensitive SGCAs as structural colored materials.
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Acknowledgements
This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (A/23245046 and S/15H05758).
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Ueno, K., Fukai, T. & Watanabe, M. Thermosensitive soft glassy colloidal arrays of block-copolymer-grafted silica nanoparticles in an ionic liquid. Polym J 48, 289–294 (2016). https://doi.org/10.1038/pj.2015.105
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DOI: https://doi.org/10.1038/pj.2015.105
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