Abstract
The preparation of polymer nanoparticles with a uniform size and shape, beyond spheres, is an unresolved problem. Here we report a living aqueous catalytic polymerization, resulting in particles grown by a single active site and composed of a single ultra high molecular weight polyethylene (UHMWPE) chain. The control on a molecular level (Mw/Mn = 1.1–1.2) and at the same time on a particle level (PDI < 0.05) together with the immediate deposition of the growing chain on the growing nanocrystal results in a distinct evolution of the particle morphology over time. These uniform nanocrystals are obtained as concentrated aqueous dispersions of > 10 wt-% (N ≈ 1019 particles L−1) polymer content. Key to this robust procedure to single chain nanoparticles are long-lived water-stable Ni(II) catalysts that do not undergo any chain transfer. These findings are a relevant step towards polymer materials based on nanoparticle assembly.
Highlights
The preparation of polymer nanoparticles with a uniform size and shape, beyond spheres, is an unresolved problem
Single-chain particles have been much studied, and the field continues to expand.[6,7,8,9]. They are commonly prepared by a post-polymerization collapse or assembly from solutions of separately synthesized chains
We show a different approach, namely direct polymerization to single-chain uniform-shape monodisperse nanocrystals (Fig. 1). We demonstrate this for polyethylene, the largest and most important synthetic polymer material
Summary
The preparation of polymer nanoparticles with a uniform size and shape, beyond spheres, is an unresolved problem. These uniform nanocrystals are obtained as concentrated aqueous dispersions of > 10 wt-% (N ≈ 1019 particles L−1) polymer content Key to this robust procedure to single chain nanoparticles are long-lived water-stable Ni(II) catalysts that do not undergo any chain transfer. These findings are a relevant step towards polymer materials based on nanoparticle assembly. A key to nanoparticle-based materials is the ability to access nanoparticles with uniform shapes and sizes. We show a different approach, namely direct polymerization to single-chain uniform-shape monodisperse nanocrystals (Fig. 1). We demonstrate this for polyethylene, the largest and most important synthetic polymer material
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