A side-chain engineering approach to solvent-resistant semiconducting polymer thin films†
Side-chain manipulation of isoindigo-thiophene derived conjugated polymers was achieved by statistical copolymerization of two different isoindigo monomers decorated with t-Boc groups and polyisobutylene chains, respectively. The long polyisobutylene side-chains ensured solution-processability of the polymers while the t-Boc groups served as a cleavable H-bond inhibitor. By post-film-casting thermal treatment, the t-Boc groups could be removed efficiently to generate a H-bond cross-linked polymer network, which demonstrated excellent solvent resistance. Organic field-effect transistor devices made from these thin films demonstrated retained electronic properties after being immersed in organic solvents. By taking advantage of the post-annealing solvent resistant feature, multilayered films of the polymers could be fabricated using multiple “casting–annealing–casting–annealing” cycles.