Spontaneous evolution of nanostructures by light‐driven growth of micelles obtained from in situ nanoparticlization of conjugated polymers

Abstract

To simplify processes to produce self-assembled nanostructures from polymeric materials, there have been several attempts for in situ self-assembly of block copolymers. As one of these strategies, we developed the in situ nanoparticlization of conjugated polymers (INCP) process to construct various stable nanostructures without postsynthetic treatments. To get spontaneous mesoscopic evolution of the nanostructures obtained by INCP, a new strategy utilizing a unique conformational change of the conjugated polymer is reported herein. The combination of living ring-opening olefin metathesis polymerization (ROMP) and cyclopolymerization produced block and gradient copolymers through one-pot or one-shot polymerization, which initially formed spherical micelles via INCP. Then, the core block of the micelle stiffened through a coil-torod conformational change by simple aging in organic solvents because of cis-to-trans isomerization of the conjugated polymer under light. Subsequently, this enhanced the p-p interaction among the cores, and eventually promoted the growth of stable nanostructures from spheres to 1D-nanocaterpillars or 2D-sheet-like architectures. This time-dependent macroscopic evolution provides deeper insight into the production of a variety of kinetically fixed nano-and mesoscale structures through INCP.

Rapid formation and real-time observation of micron-sized conjugated nanofibers with tunable lengths and widths in 20 minutes by living crystallization-driven self-assembly

“…1b and c). 48 The BCP having the shortest core block of P2 10 was still in an unimeric state due to its low crystallinity. A further decrease in the signals for the core block P2 via the 1 H NMR spectra was also observed.…”

Direct formation of nano-objects via in situ self-assembly of conjugated polymers

“…Nanospheres were also obtained during the block copolymerization of NB4 or TD1 and HD1. 47 Higher-order morphologies (1D or 3D nanostructures) were not obtained from the INCP of PCPV-based BCPs. However, higher-order morphologies could be obtained by aging or photo-isomerization of the alkene bonds in the polymer backbone.…”

Crosslinked Polydicyclopentadiene Nanoparticles via Ring‐Opening Metathesis Polymerization‐Induced Self‐Assembly Approach

“…The postcrosslinking of PONBDM blocks was achieved via 2 + 2 addition of cinnamyl moieties under UV irradiation. Although there have been many reports on ROMPISA, [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] the ROMPISA systems reported up to now are mainly involved with the syntheses of diblock copolymers and crosslinking of nanoparticles was only achieved in a post-ROMPISA manner. To the best of our knowledge, there has been no previous report that ROMPISA was carried out by using dicyclopentadiene (DCPD) and that the crosslinking of nanoparticles is in situ carried out in the process of polymerization.…”

“…To mediate the ROMPs, poly( -caprolactone)s with cis-butene structural units in the middle of chains were synthesized and used as the macromolecular chain transfer agent, which was in marked contrast to those polynorbornene-based initiators. [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] Notably, the crosslinking was carried out via an approach of in situ polymerization.…”

“…[ 23–29 ] Ring‐opening metathesis polymerization (ROMP) has been also exploited to obtain polymer nanoobjects via PISA approach. [ 30–51 ] Xie and coworkers [ 30 ] first reported that block copolymer nanoobjects were synthesized via ring opening metathesis polymerization induced self‐assembly (ROMPISA) in toluene and with poly(2,3‐bis(2‐bromoisobutyryloxymethyl)‐5‐norbornene) (PBNBE) as the macromolecular initiator (or stabilizer) and with poly(oxanorbornene dicarboxylic acid dimethyl ester) (PONBDM) as the core‐forming block. The same group [ 31 ] further explored to synthesize crosslinked PONBDM nanoobjects by introducing cinnamyl‐based ONB monomer.…”