Structure of colloidal gels at intermediate concentrations: the role of competing interactions. Issue 46 (1st November 2016)

• Record Type: Journal Article
• Authors: Capellmann, Ronja F.; Valadez-Pérez, Néstor E.; Simon, Benedikt; Egelhaaf, Stefan U.; Laurati, Marco; Castañeda-Priego, Ramón
• Is Part Of: Soft matter. Volume 12:Issue 46(2016)
• Page Start: 9303
• Page End: 9313
• Publication Date: 2016-11-01
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/c6sm01822j
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : The structure of gels formed by colloid–polymer mixtures is investigated by confocal microscopy and successfully modelled by computer simulations, despite their non-equilibrium state. Abstract : Colloidal gels formed by colloid–polymer mixtures with an intermediate volume fraction ( ϕ c ≈ 0.4) are investigated by confocal microscopy. In addition, we have performed Monte Carlo simulations based on a simple effective pair potential that includes a short-range attractive contribution representing depletion interactions, and a longer-range repulsive contribution describing the electrostatic interactions due to the presence of residual charges. Despite neglecting non-equilibrium effects, experiments and simulations yield similar gel structures, characterised by, e.g., the pair, angular and bond distribution functions. We find that the structure hardly depends on the strength of the attraction if the electrostatic contribution is fixed, but changes significantly if the electrostatic screening is changed. This delicate balance between attractions and repulsions, which we quantify by the second virial coefficient, also determines the location of the gelation boundary.