Simple Preparation of Various Nanostructures via <i>in Situ</i> Nanoparticlization of Polyacetylene Blocklike Copolymers by One-Shot Polymerization

Abstract

Previously, we reported the one-pot synthesis of polyacetylene (PA) diblock copolymers which formed various nanostructures via the <i>in situ</i> nanoparticlization of conjugated polymers (INCP), using a two-step protocol based on sequential monomer addition. Herein, we report a much simpler one-shot method for nanostructure formation by the synthesis of PA blocklike copolymers. The blocklike copolymers could be prepared by the one-shot ROMP of comonomers with large differences in their reactivities because the monomers that formed the first block, namely norbornene (NB) derivatives or <i>endo</i>-tricyclo­[4.2.2.0]­deca-3,9-diene (TD) derivatives, polymerized much faster than the monomers that formed the second PA block, cyclooctatetraene (COT). Owing to their blocklike microstructures, the copolymers formed various nanostructures such as nanospheres, nanocaterpillars, and nanoaggregates depending on the chemical structures of the soluble shell polymers and feed ratio of COT, which formed the insoluble PA core. Using dynamic light scattering (DLS) and atomic force microscopy (AFM), it was observed that the nanostructures produced from the blocklike copolymers were essentially the same as those produced from the block copolymers synthesized by conventional sequential monomer addition. The blocklike microstructures of the copolymers formed by one-shot ROMP were further supported by an <i>in situ</i> ¹H NMR kinetic experiment and UV/vis spectroscopy. From these results, we were able to confirm that the ROMP of TD and COT produced near-perfect block copolymers. Furthermore, the ¹H NMR spectra of the one-shot copolymerization provided insights into the INCP process