Issue 15, 2016

Isostructural solid–solid phase transition in monolayers of soft core–shell particles at fluid interfaces: structure and mechanics

Abstract

We have studied the complete two-dimensional phase diagram of a core–shell microgel-laden fluid interface by synchronizing its compression with the deposition of the interfacial monolayer. Applying a new protocol, different positions on the substrate correspond to different values of the monolayer surface pressure and specific area. Analyzing the microstructure of the deposited monolayers, we discovered an isostructural solid–solid phase transition between two crystalline phases with the same hexagonal symmetry, but with two different lattice constants. The two phases corresponded to shell–shell and core–core inter-particle contacts, respectively; with increasing surface pressure the former mechanically failed enabling the particle cores to come into contact. In the phase-transition region, clusters of particles in core–core contacts nucleate, melting the surrounding shell–shell crystal, until the whole monolayer moves into the second phase. We furthermore measured the interfacial rheology of the monolayers as a function of the surface pressure using an interfacial microdisk rheometer. The interfaces always showed a strong elastic response, with a dip in the shear elastic modulus in correspondence with the melting of the shell–shell phase, followed by a steep increase upon the formation of a percolating network of the core–core contacts. These results demonstrate that the core–shell nature of the particles leads to a rich mechanical and structural behavior that can be externally tuned by compressing the interface, indicating new routes for applications, e.g. in surface patterning or emulsion stabilization.

Graphical abstract: Isostructural solid–solid phase transition in monolayers of soft core–shell particles at fluid interfaces: structure and mechanics

Supplementary files

Article information

Article type
Paper
Submitted
18 ธ.ค. 2558
Accepted
25 ก.พ. 2559
First published
25 ก.พ. 2559

Soft Matter, 2016,12, 3545-3557

Isostructural solid–solid phase transition in monolayers of soft core–shell particles at fluid interfaces: structure and mechanics

M. Rey, M. Á. Fernández-Rodríguez, M. Steinacher, L. Scheidegger, K. Geisel, W. Richtering, T. M. Squires and L. Isa, Soft Matter, 2016, 12, 3545 DOI: 10.1039/C5SM03062E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements