Tailoring Low‐Polarity Ionic Liquids Using Polyhedral Oligomeric Silsesquioxane (POSS) for Advanced Polymer Hybrids

The effects of the POSS core on the microenvironment around dyes in ionic liquids (ILs) were investigated through normalized polarity (E _T ^N) and Kamlet–Taft parameters with several types of solvatochromic dyes as a probe. Consequently, it was revealed that POSS core should provide a low-polar environment even in ILs. Additionally, POSS could play a critical role in enhancing intermolecular interactions from the directly-connected anion to other species including cations and dyes. Furthermore, we obtained the hybrid films containing POSS IL and conventional conjugated polymers, and confirmed that each polymer chain can be isolated even under ionic environments owing to POSS.

Abstract

Polyhedral oligomeric silsesquioxane (POSS) can create hydrophobic spaces in various media including water-soluble networks and dendrimers. In particular, since the development of POSS ionic liquids (ILs), much effort has been devoted to investigating their thermal properties. In this manuscript, we report that POSS can create hydrophobic spaces in ILs. In comparison with a series of POSS ILs and ion pairs, we investigated the effects of the POSS core on the microenvironment around dyes in ILs by evaluating normalized polarity and Kamlet–Taft parameters with several types of solvatochromic dyes as probes. Consequently, it was revealed that POSS ILs should have low polarity where POSS could play a critical role in enhancing intermolecular interactions from the directly-connected anion to other species including cations and dyes. In terms of applications, it was found that low-polarity POSS ILs have high compatibility with conventional conjugated polymers, which can be used for fabricating highly-efficient luminescent ionic-liquid hybrid films owing to the isolation of each polymer chain by POSS even under ionic environments.

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