Abstracts Book - IMRC 2018

• SB1-P095
FORMATION OF PHYSICAL GELS BY ARRESTED SPINODAL
DECOMPOSITION IN CHARGED COLLOIDS
Alonso Gomez Canales 1 , Jose Manuel Olais Govea 1 , Magdaleno Medina Noyola 2
1 Instituto Tecnológico y de Estudios Superiores de Monterey, Escuela de Ingenieria y Ciencias,
Mexico. 2 Universidad Autónoma de San Luis Potosí, Departamento de Física, Mexico.
The general understanding of gelation processes is recognized as a major
challenge in soft matter. Particularly, attractive liquids that suffer a suddenly
instantaneous isochoric quench an homogeneous state to thermodynamic
instability could form a physical gel. Although, both experimental and simulation
advances in understanding gelation phenomenon had led to build a general
comprehension about physical gel properties and even had discussed the
perform of novel materials as amorphous solids, there is no a clear theoretical
approach to explain these class of ubiquitous materials. In recent work,
however, the general theory, referred to as the non-equilibrium self-consistent
generalized Langevin equation (NESCGLE) theory, based on a non- equilibrium
extension of Onsager’s canonical theory of thermal fluctuations, was adequately
adapted to describe memory effects, protocol-dependent preparation and
irreversible aging processes associated with the glass and the gel transitions in
attractive simple liquids. In particular, this theory was capable of predict a glassglass
transition line and propose a glass-gel line in a monocomponent attractive
Yukawa simple fluid (HSAY) by arested spinodal decomposition when that
system is instantaneously quenched inside spinodal region. In the present work
we discuss the application of this general theory to the context of a very specific
model system, namely, let us consider an screened restricted primitive model
(YRPM), for example an electrolyte solution or molten salt, represented as an
electroneutral mixture of charged hard spheres embedded in a dielectric
medium of uniform dielectric constant ε. Concretely, this work addresses the
problem of adapting a mixture colloidal system in a monocomponent one,
applying the NESCGLE theory to delineate the glass-glass and the gelation lines
in an astonish non-equilibrium phase diagram by means of two dynamical order
parameters: (i) the mobility function b(t) (the inverse of long time self-difussion
coefficient) and the localization lenght γ(t) under the simplest conditions: spatial
homogenety and in absent of external fields and without consider temperature
gradients. We show pertinent comparisons between our theoretical results and
the gel formation in a mixture of equally-sized oppositely charged colloids both
experimentally and by means of computer simulations.