Improved Electro‐Optic Effect by Hyperbranched Chromophore Structures in Side‐Chain Polyimide

Abstract Hyperbranched structures of chromophores were developed to improve the nonlinearity of optical polymers. Macromolecules with 3‐[p‐(2′‐hydroxyethylmethylamino)styryl]‐1‐dicyanomethylene‐5,5‐dimethylcyclohex‐2‐ene (AIDC) were prepared using 3,5‐dihydroxyphenyl groups as building blocks. When the molecule was incorporated into a polyimide backbone (PI‐DAIDC101), a high electro‐optic coefficient was obtained, giving 32 pm · V−1 at 1.55 μm. The nonlinearity is at least doubly enhanced in comparison with that of conventional side chain‐optical polyimides. This is mainly attributable to an increased polarizing efficiency derived from the chromophore structures. The structure of the linear polyimide backbone (PI‐OH) and the chromophore‐attached optical polyimide (PI‐DAIDC101). image The structure of the linear polyimide backbone (PI‐OH) and the chromophore‐attached optical polyimide (PI‐DAIDC101).