Hydrogen-bonding-directed helical nanofibers in a polythiophene-based all-conjugated diblock copolymer

One-dimensional (1D) helical nanofibers were prepared through the self-assembly of an achiral all-conjugated diblock copolymer, poly(3-hexylthiophene)-b-poly[3-(6-hydroxyl) hexylthiophene] (P3HT-b-P3HHT) in an aged pyridine solution. Such helical nanofibers were formed by the pi-pi interaction between planar rigid polythiophene backbones cooperating with the hydrogen-bonding interactions between the polar hydroxyl groups of the side chains of polythiophenes. Intriguingly, the Young's modulus of such helical fibers is as high as similar to 5.16 GPa, which is about twice that of P3HT films characterized by the peak force quantitative nanomechanical (PF-QNM) method. Furthermore, for the first time, we report that such helical fibers based on all-conjugated polythiophenes exhibited a relatively high field-effect mobility of 0.03472 cm(2) V-1 s(-1). This work provides a promising approach to craft crystalline helical nanostructures based on polythiophenes possessing both superior mechanical and good charge transport properties, which has great potential for application in other pi-conjugated systems or building blocks for complex superstructures, and mechanical and optoelectronic devices.