Bottlebrush Polymers Carrying Side Chains on Every Backbone Atom: Controlled Synthesis, Polymerization-Induced Emission, and Circularly Polarized Luminescence

Abstract

Controlled synthesis of bottlebrush polymers with high grafting density and carrying polymeric side chains on every backbone atom remains a great challenge. In this work, a series of well-defined poly­(l-lactic acid) (PLLA) and poly­(d-lactic acid) (PDLA) bearing polymerizable phenyl isocyanide on chain ends were prepared. Polymerization of the terminal phenyl isocyanide of these macromonomers by an alkyne-palladium­(II) catalyst yielded bottlebrush polymers carrying PLLA or PDLA side chains on every backbone atom. The grafted side chains were directly packed together without separating from other atoms. The polymerizations were proceeded in a living/controlled manner, and the degree of polymerization could be up to 250. The chiral macromonomers induced an asymmetric polymerization and resulted in a poly­(phenyl isocyanide) backbone with a preferred one-handed helix and large optical activity. Remarkably, the densely grafted bottlebrush polymers exhibited intriguing photoluminescence, although the macromonomers and poly­(phenyl isocyanide) backbone were all nonluminescent. Moreover, the preferred one-handed helix of the backbone induced clear circularly polarized luminescence (CPL) with defined handedness and a tunable dissymmetric factor.

Room-temperature Barbier single-atom polymerization induced emission as a versatile approach for the utilization of monofunctional carboxylic acid resources

“…These changes indicate that the polymerization will affect the molecular orbitals and narrow the corresponding bandgap, causing through-space conjugation and an intramolecular charge transfer effect under the constraint of polymer chains, resulting in nonconjugated luminescence eventually, which is similar to the PIE literature. 52,[55][56][57][59][60][61][62] Meanwhile, the structure-specific luminescence of PIE obeys the restriction of intramolecular rotation theory, which is similar to the AIE literature. [63][64][65] It is worth mentioning that PIEgens can be easily adjusted between ACQ and AIE by simply adjusting the connection mode of the phenyl containing monomer, which enables easier molecular design of PIEgens.…”

Frontiers in circularly polarized luminescence: molecular design, self-assembly, nanomaterials, and applications

“…CPL polymers can also be constructed via introducing chiral factors into the side chains of fluorescent conjugated polymers, such as polysilane [120], polyquinoxaline [121], polyfluorene [122], polyisocyanide [123], polytriazole [65], polythiophene [124], and polycarbazole [125]. For example, Wu and co-workers [126] synthesized amphiphilic poly(3hexylthiophene)-block-poly(phenyl isocyanide)s (P3HT-b-PPI) copolymers 41, which further self-assembled into single-handed helical nanofibers (Figure 14c).…”

Chiral transfer‐dictated self‐assembly of chiral block copolymers

“…[233] It was found that the aggregation and chiral transfer of chiral small molecules, chiral homopolymers and chiral peptides endowed a chiral optical resonance of pertinent functional groups in the system, such as induced CD (ICD) and circularly CPL emission. [234][235][236] For BCPs*, Ho et al manifested that the chiral transferdictated self-assembly of PS-b-PLLA into the bulk helix* phase caused the ICD of achiral perylene moiety, which served as the chemical junction of PS and PLLA blocks. Such ICD was due to the intramolecular chiral interaction between PS and PLLA blocks.…”