Luminescent Iridium-containing liquid crystalline polymers in the side chain

ABSTRACT

Luminescent liquid crystalline polymers consisting of Iridium attached to polysiloxanes are prepared. 4-Cyanophenyl 4-(allyloxy) benzoate (M₁) and an Iridium complex (Ir-M₂) grafted to poly(methylhydrogeno)siloxane are used for the preparation of the Iridium-containing liquid crystalline polymers. The chemical structures are characterised by Fourier transform infrared spectroscopy and ¹H NMR. The mesomorphic properties and phase behaviour are investigated by differential scanning calorimetry, thermogravimetric analysis, polarising optical microscopy and X-ray diffraction. The polymers containing <1.2 mol% of the Iridium ions reveal reversible mesomorphic phase transition, wide mesophase temperature ranges and high thermal stability. The introduction of the Iridium ions does not change the liquid crystalline state of polymer systems; on the contrary, the polymers are enabled with the luminescent properties. With the Iridium ion contents ranging between 0.3 and 1.2 mol%, luminescent intensity of polymers gradually increased. The temperature dependence of luminescent intensity was studied in the liquid crystalline phase.

GRAPHICAL ABSTRACT

KEYWORDS:

• Graft copolymers
• luminescence
• liquid crystalline polymers (LCP)
• thermal properties

Acknowledgements

The authors acknowledge the financial support received from the National Key Technology Support Program of China [contract grant number 2008BAL55B03].

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the National Key Technology Support Program of China [2008BAL55B03].