Dongle Liu, Zicheng Ding,* Yin Wu, Shengzhong Frank Liu, Yanchun Han, and Kui Zhao*

ABSTRACT:

Conjugated polymers exhibit potential for the development of next-generation stretchable electronics. However, an

understanding of molecular aggregation during solution processing and its influence on thin-film morphology is still underexplored.

Here, the influences of molecular aggregation on the film morphology, phase purity and phase separation, and mechanical and

electrical properties of a partially compatible blend of conjugated polymer poly(indacenodithiophene-co-benzothiadiazole)

(IDTBT) and elastomer polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) were systematically examined.

When using high-boiling-point (b.p.) solvents, namely, toluene and chlorobenzene, large-scale liquid−liquid phase separation

predominates IDTBT aggregation in blend films, leading to isolated IDTBT domains and, thus, poor electrical performance. In

contrast, fast solvent evaporation from low-b.p. chloroform suppresses large-scale phase separation and enhances IDTBT aggregation

via nanoconfinement effect. The nanoconfinement effect enables us to achieve a stretchable film with a low elastic modulus of 72

MPa, a respectable crack-onset strain of 326% (ca. 3−14 times larger than the neat IDTBT films), and a negligible loss of mobility

(ca. 0.7 cm2 V−1 s−1) at 100% strain. These results provide insight into molecular aggregation and thin-film morphology in

conjugated polymer/elastomer blends for high-performance stretchable electronics.

https://doi.org/10.1021/acs.macromol.1c01537