Achieving In Situ Photoisomerization of Fluorene-Based Polymers on the Surface of s-SWCNTs for Bare s-SWCNTs Release

Abstract

The efficient release of semiconducting single-walled carbon nanotubes (s-SWCNTs) from conjugated polymer wrappers via photoisomerization under light stimuli is attractive but has not been achieved yet and remains challenging. Herein, we report a photoisomerization polymer of PFDD-CS, by incorporating a cyano-styrene linker featuring a twisted conjugate structure. It can undergo only the desired trans-to-cis photoisomerization, but not the normal photocyclization nor photoaddition for cyano-styrene derivatives. Particularly, it can even occur in situ successfully on the nanotube surface under light stimuli, facilitating the release of bare s-SWCNTs. Experimental results revealed that the twisted conjugate structure of the initial trans-form contributes to the mobility on the surface of s-SWCNTs, while the significant conformational differences between the trans- and cis-isomers facilitate polymer detachment and bare s-SWCNT release. This work provides a mild, light-triggered strategy for obtaining pure nanotubes and advances the development of stimuli-responsive polymers for nanomaterials processing.