Conjugated polymer with dynamic and thermoreversible hydrogen bonding on the backbone

Abstract Two conjugated polymers containing isoindigo (IIDG) or 3,3-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI) with latent hydrogen bonding were synthesized and characterized. The tert-butyloxycarbonyl (t-Boc) side unit could be removed by facile thermal annealing treatment, generating the actual hydrogen-bonded, fully conjugated polymers. Despite the similar structure of IIDG and EBI, the hydrogen bonds formed in two polymers are different. The polymer based on IIDG possesses a “fixed” hydrogen bonding, which won't be dissociated before thermal degradation. On the contrary, the polymer based on EBI exhibits dynamic and thermoreversible hydrogen bonds upon heating and cooling cycles. The dynamic hydrogen bonding enables the investigation of these special conjugated polymers under the decoupling conditions of hydrogen bonding and other intermolecular interactions. Kinetic FTIR was applied to study the association/dissociation process of hydrogen bonds in the polymer. It is demonstrated that the ratio of hydrogen-bonded donor-acceptor units in the polymer thin film could be determined and its impact on optical properties and charge transport was investigated. The results also suggested that the hydrogen bonding driven molecular aggregation in the polymer thin film enhanced the charge transport mobility in the thin film transistor devices.