Synchronous Preparation of Length-Controllable 1D Nanoparticles via Crystallization-Driven In Situ Nanoparticlization of Conjugated Polymers

Abstract

Precise size control of semiconducting nanomateri-als from polymers is crucial for optoelectronic applications, but thelow solubility of conjugated polymers makes this challenging.Herein, we prepared length-controlled semiconducting one-dimen-sional (1D) nanoparticles by synchronous self-assembly duringpolymerization. First, we succeeded in unprecedented livingpolymerization of highly soluble conjugated poly(3,4-dihexylth-iophene). Then, block copolymerization of poly(3,4-dihexylth-iophene)-block-polythiophene spontaneously produced narrow-dispersed 1D nanoparticles with lengths from 15 to 282 nmaccording to the size of a crystalline polythiophene core. The keyfactors for high efficiency and length control are a highlysolubilizing shell and slow polymerization of the core, therebyfavoring nucleation elongation over isodesmic growth. Combining kinetics and high-resolution imaging analyses, we propose aunique mechanism called crystallization-drivenin situnanoparticlization of conjugated polymers (CD-INCP) where spontaneousnucleation creates seeds, followed by seeded growth in units of micelles. Also, we achieved"living"CD-INCP through a chain-extension experiment. We further simplified CD-INCP by adding both monomers together in one-shot copolymerization but stillproducing length-controlled nanoparticles.