The advancement of bioelectronic devices requires flexible electronic materials, which allow for improved conformation between the devices and the body. Solution processable semiconducting polymers are promising for this purpose given their low fabrication costs and large scale manufacturing capabilities. Previous studies report that blending semiconducting polymers with an insulating polymer can both modulate the thin film’s morphology and improve its electronic performance. However, a variety of factors will affect the final blended film morphology, i.e., processing conditions, polymer structure, and solvent selection. In this study, the insulating polymer’s molecular weight is studied with respect to the aggregation, molecular ordering, and electronic properties of the thin film structure, due to molecular weight’s known impact on both polymer interactions and the kinetics of crystallization. The insulating polymer, polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS), has been shown to induce stretchability while improving the electronic properties in films. Thus, as part of this study, spincast films of diketopyrrolopyrrole (DPP)-based conjugated polymers blended with SEBS of various molecular weights were characterized. Optical (UV-Vis) spectroscopy and grazing incidence wide-angle x-ray scattering (GIWAXS) methods were employed to study the aggregation, planarization of the polymer backbone, and crystallinity of the thin films. Aggregation and planarization of the polymer backbone of the DPP-based polymer was found to decrease when the molecular weight of SEBS is increased. The effect that SEBS’ molecular weight has on the aggregation and crystallization process in the films will be further discussed in the context of their impact on the electronic properties of the material. These findings on the molecular weight’s effect on blended film morphologies will support the development of more systematic methods for the tailoring of films for specific uses, such as bioelectronics.

Effect of an insulating polymer’s molecular weight on semiconducting/ insulating polymer blend morphology for stretchable electronic devices

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.