The precise control of the shape, size and microstructure of nanomaterials is of high interest in chemistry and material sciences. However, living lateral growth of cylinders is still very challenging. Herein, we propose a crystallization-driven fusion-induced particle assembly (CD-FIPA) strategy to prepare cylinders with growing diameters by the controlled fusion of spherical micelles self-assembled from an amphiphilic homopolymer. The spherical micelles are heated upon glass transition temperature (Tg) to break the metastable state to induce the aggregation and fusion of the amorphous micelles to form crystalline cylinders. With the addition of extra spherical micelles, these micelles can attach onto and fuse with the cylinders, showing the living character of the lateral growth of cylinders. Computer simulations and mathematical calculations are preformed to reveal the total energy changes of the nanostructures during the self-assembly and CD-FIPA process. Overall, we demonstrated a CD-FIPA concept for preparing cylinders with growing diameters.
The stimuli‐responsive transition of nanostructures from amorphous to crystalline state is of high interest in polymer science, but is still challenging. Herein, the transformation of amorphous nanobowls to crystalline ellipsoids triggered by UV induced trans‐cis isomerization is demonstrated, using an azobenzene‐containing amphiphilic homopolymer (PAzoAA) as a building block. The amide bond and azobenzene pendants are introduced to the side chain of PAzoAA to afford hydrogen bonding and π–π interactions, which promote the formation of nanobowls rather than spherical nanostructures. Upon exposure to UV irradiation, trans‐cis isomerization of azobenzene pendants occurs, leading to the increase of hydrophilicity and destruction of π–π interaction, further resulting in the disassembly of the nanobowls. Then the PAzoAA re‐assembles to form crystalline ellipsoids instead of amorphous nanostructures when recovered at 70 °C without UV light. Further, it is confirmed that the high incubation temperature after UV irradiation is critical for the cis‐trans transformation and the high mobility of the polymer chains to facilitate the regular rearrangement of azobenzene pendants. Overall, a facile method to achieve the transformation of amorphous nanobowls to crystalline ellipsoids is proposed, which may bring new insight into preparation of crystalline nanoparticles using amorphous precursors.
The control over the morphology and nanostructure of soft nanomaterials self-assembled from amphiphilic polymers is of high interest, but is still challenging. Herein, we manipulate the morphology of bowl-shaped nanoparticles...
Polymeric toroids are fascinating soft nanostructures due to their unique geometry and properties, which have shown potential applications in the fields of nanoreactors, drug delivery, cancer therapy, etc. However, facile preparation of polymeric toroids is still challenging. Herein, we propose a fusion-induced particle assembly (FIPA) strategy to prepare polymeric toroids using anisotropic bowl-shaped nanoparticles (BNPs) as a building block. The BNPs are prepared in ethanol by the self-assembly of an amphiphilic homopolymer, poly(N-(2,2′bipyridyl)-4-acrylamide) (PBPyAA), synthesized via reversible addition−fragmentation chain transfer (RAFT) polymerization. Upon incubation in ethanol above the glass transition temperature (T g ) of PBPyAA, the BNPs gradually aggregate to form trimers and tetramers due to the disturbance of the colloidal stability. With the increase in incubation time, the aggregated BNPs fuse with each other and then form toroids. Notably, we find that only anisotropic BNPs can aggregate and fuse to form toroids rather than spherical compound micelles due to high surface free energy and curvature at the edge of the BNPs. Besides, mathematical calculations further confirm the formation of trimers and tetramers during the FIPA process and the driving force for the formation of toroids. Overall, we propose a fresh insight for the facile preparation of polymeric toroids by the FIPA of anisotropic BNPs.
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