Revealing polymerization kinetics with colloidal dipatch particles

Abstract

Limited-valency colloidal particles can self-assemble into polymeric structures analogous to molecules. While their structural equilibrium properties have attracted wide attention, insight into their dynamics has proven challenging. Here, we investigate the polymerization dynamics of semiflexible polymers in two dimensions (2D) by direct observation of assembling divalent particles, bonded by critical Casimir forces. The reversible critical Casimir force creates living polymerization conditions with tunable chain dissociation, association and bending rigidity. We find that unlike dilute polymers that show exponential size distributions in excellent agreement with Flory theory, concentrated samples exhibit arrest of rotational and translational diffusion due to a continuous isotropic-to-nematic transition in 2D, slowing down the growth kinetics. These effects are circumvented by addition of higher-valency particles, cross-linking the polymers into networks. Our results connecting polymer flexibility, polymer interactions and the peculiar isotropic-nematic transition in 2D offer insight into polymerization processes of synthetic two-dimensional polymers, and biopolymers at membranes and interfaces.

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Cited by in corpus (4)

• Critical Casimir Effect: Exact Results
• Fluctuation-induced Interactions in Micro- and Nano-systems: Survey of Some Basic Results
• Extended Wertheim theory predicts the anomalous chain length distributions of divalent patchy particles under extreme confinement
• Quantum and Critical Casimir Effects: Bridging Fluctuation Physics and Nanotechnology