Patternable Conjugated Polymers with Latent Hydrogen-Bonding on the Main Chain

Conjugated polymers with latent hydrogen-bonding on the main chain were synthesized using Suzuki coupling reaction. The resulting polymers with latent hydrogen-bonding can be converted to the actual hydrogen-bonded polymers by thermal annealing or UV irradiation. As the hydrogen-bonding sites are fused with π-conjugated units on the polymer backbone, the intermolecular interactions between the polymer chains will be strongly enhanced when the hydrogen-bonds are formed. By removing the protection group and forming hydrogen-bonding, the polymers exhibited a bathochromic shift over those with latent hydrogen-bonding, indicating a hydrogen-bonding-mediated enhancement of π–π stacking. In addition, the fused hydrogen-bond sites and π-conjugated units led to closely packed polymer chains, resulting in insoluble pigment-like polymers. This drastic solubility change from polymers with latent hydrogen-bonding to hydrogen-bonded polymers can be used to pattern conjugated polymers directly. The photolithography of the conjugated polymer with latent hydrogen-bonding was demonstrated, and the patterned electrochromic devices were fabricated and tested.