Crystallization‐Driven Asymmetric Helical Assembly of Conjugated Block Copolymers and the Aggregation Induced White‐light Emission and Circularly Polarized Luminescence

Abstract

Controlling the self‐assembly morphology of π‐conjugated block copolymer is of great interesting. Herein, amphiphilic poly(3‐hexylthiophene)‐block‐poly(phenyl isocyanide)s (P3HT‐b‐PPI) copolymers composed of π‐conjugated P3HT and optically active helical PPI segments were readily prepared. Taking advantage of the crystallizable nature of P3HT and the chirality of the helical PPI segment, crystallization‐driven asymmetric self‐assembly (CDASA) of the block copolymers lead to the formation of single‐handed helical nanofibers with controlled length, narrow dispersity, and well‐defined helicity. During the self‐assembly process, the chirality of helical PPI was transferred to the supramolecular assemblies, giving the helical assemblies large optical activity. The single‐handed helical assemblies of the block copolymers exhibited interesting white‐light emission and circularly polarized luminescence (CPL). The handedness and dissymmetric factor of the induced CPL can be finely tuned through the variation on the helicity and length of the helical nanofibers.

Emerging applications for living crystallization-driven self-assembly

“…However, subsequent extensions to other crystallizable polymer systems has led to major expansion of the field and has enhanced the possibility for a wide variety of applications. Studies reported since 2011 have involved PLLA, [165][166][167] PE, 168 PFDES, 38 and also hyperbranched poly(ether amine) capped with polyhedral oligomeric silsesquioxane, 143 PCL, 169,170 polycarbonate, 62,171 and π-conjugated polymers such polythiophene, [172][173][174][175] poly(3heptylselenophene), 176 PDHF, 177 oligo(p-phenylenevinylene) (OPV), 178,179 poly(cyclopentenylenevinylene) 180 and oligo(p-phenylene-ethynylene). 181 The use of the living CDSA seeded-growth approach to fabricate well-defined biopolymerbased assemblies has also been reported.…”

“…Recently, single-handed helical nanofibers with controlled length and handedness have been fabricated through the living CDSA of amphiphilic BCPs composed of a crystallizable P3HT core-forming block and a corona-forming segment comprising optically active helical poly(phenyl isocyanide) segments. 172 It was found that during the self-assembly process the chirality of helical poly(phenyl isocyanide) was transferred to the nanofibers. Figure 10a), concentric 2D block comicelles 142,144,145 (see Figure 10c) and hierarchical assembles 148,164 (see…”

Circularly polarized luminescence from organic micro-/nano-structures

“…CPL-active conjugated polymer assemblies have drawn great attention owing to their well-defined structure modification, tunable luminescent properties, and easy processing 63 , 64 . They can be constructed through the following two approaches: (1) self-assembly of chiral conjugated polymers, including main-chain chiral conjugated polymers and conjugated polymers with chiral side-chain; (2) doping achiral conjugated polymers with chiral additives.…”

“…Decorating the conjugated polymer with chiral pendants provides an alternative choice, and various CPL-active conjugated polymer systems ( 34–39 ) have been developed 64 , 68 – 70 , where the chiral pendants play an important role in the arrangement of the polymer chains. Typically, chiral π-conjugated block copolymers 34 composed of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(phenyl isocyanide) (PPI) with chiral substituent were prepared 64 . Employing the crystallinity of P3HT and the chirality of PPI, the approach of crystallization-driven asymmetric self-assembly was developed to construct helical structures.…”

Helicity‐ and Molecular‐Weight‐Driven Self‐Sorting and Assembly of Helical Polymers towards Two‐Dimensional Smectic Architectures and Selectively Adhesive Gels

“…Among the developed helical polymers, polyisocyanide is of great interesting, because of its unique rod‐like helical structure and wide applications [36–42] . Polyisocyanide is generally prepared via the polymerization of the corresponding isocyanide monomer by using transition metal complexes or cations as catalysts [43–46] .…”