Issue 40, 2015

Gelation and mechanical response of patchy rods

Abstract

We perform Brownian dynamics simulations to study the gelation of suspensions of attractive, rod-like particles. We show that in detail the rod–rod surface interactions can dramatically affect the dynamics of gelation and the structure and mechanics of the networks that form. If the attraction between the rods is perfectly smooth along their length, they will collapse into compact bundles. If the attraction is sufficiently corrugated or patchy, over time, a rigid space-spanning network will form. We study the structure and mechanical properties of the networks that form as a function of the fraction of the surface, f, that is allowed to bind. Surprisingly, the structural and mechanical properties are non-monotonic in f. At low f, there are not a sufficient number of cross-linking sites to form networks. At high f, rods bundle and form disconnected clusters. At intermediate f, robust networks form. The elastic modulus and yield stress are both non-monotonic in the surface coverage. The stiffest and strongest networks show an essentially homogeneous deformation under strain with rods re-orienting along the extensional axis. Weaker, more clumpy networks at high f re-orient relatively little with strong non-affine deformation. These results suggest design strategies for tailoring surface interactions between rods to yield rigid networks with optimal mechanical properties.

Graphical abstract: Gelation and mechanical response of patchy rods

Supplementary files

Article information

Article type
Paper
Submitted
24 Jul 2015
Accepted
08 Sep 2015
First published
10 Sep 2015
This article is Open Access
Creative Commons BY license

Soft Matter, 2015,11, 7877-7887

Author version available

Gelation and mechanical response of patchy rods

N. Kazem, C. Majidi and C. E. Maloney, Soft Matter, 2015, 11, 7877 DOI: 10.1039/C5SM01845E

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