Exploring Local and Global Stretching of Semiconducting Polymer Chains in Thin Films

The pursuit of semiconducting polymers for soft electronics has gained significant momentum to their flexibility and processability. Initial research focused on mechanically stretchable materials, but recent efforts have shifted towards understanding molecular chain orientation during stretching. Anisotropy in charge carrier mobility is observed in polythiophenes under mechanical stress, yet understanding tensile alignment, especially in rigid conjugated polymers, is lacking. Existing characterization tools offer limited insights into multi-scale chain conformation changes during stretching. Neutron scattering with deuterium labeling uniquely probes polymer chains in amorphous and crystalline regions, overcoming limitations of traditional methods. We will investigate how alkyl sidechain length influences single chain conformation during stretching of semi-rigid polymer chains in films using small angle neutron scattering (SANS). DPP-based polymers with varying side chains will be synthesized, and SANS will monitor single chain conformation. Mixing hydrogenated and deuterated polymers will provide scattering contrast, facilitating the study of local conformation changes at different length scales. Understanding the role of alkyl sidechains in local molecular conformation change is crucial for improving charge transport in these materials. This research holds promise for advancing the development of flexible and wearable electronics.