Graft Architectured Rod-Coil Copolymers Based on Alternating Conjugated Backbone: Morphological and Optical Properties

Abstract

Controlling the self-assembly of conjugated copolymers is of great importance in tuning their physical and optoelectronic properties, offering potential pathways to greatly enhance the performance of organic electronics. Here, we report the synthesis of rod-coil graft copolymers containing an electroactive conjugated rod-like backbone and polymer coils as grafts and demonstrate the control of their ordered nanostructures. As a model system, we synthesized light-emitting poly(fluorene-alt-phenylene) (PFP) alternating copolymers and then grafted poly(2-vinylpyridine) (P2VP) chains with different lengths via a "click" reaction to produce a series of PFP-g-P2VP graft copolymers with various P2VP volume fractions (f(P2VP)). Interestingly, PFP-g-P2VP rod coil copolymers assembled into well-ordered cylinders and lamellae depending on f(P2VP) values that resembled those of the coil coil type block copolymers, but with very different f(P2VP) values for the morphological transitions (i.e., cylinders to lamellae). The morphological behavior of these graft copolymers was investigated using self-consistent-field theory simulations. Furthermore, by fully exploiting the controlled nanostructures of PFP-g-P2VP and the strong emitting properties of the PFP backbone, we developed multicolor colloidal particles that emit a broad range color spectrum from blue, white, and orange light. Our synthetic approach paves a new method for modulating the self-assembled nanostructures of rod coil copolymers and their optoelectronic properties.