  An aqueous dispersion of Laponite has been studied in the literature for over
the past three decades. Typically, the aqueous dispersion of Laponite undergoes
incessant evolution of its microstructure, wherein its elastic modulus and the
mean relaxation time show a continuous increase as a function of time. A
considerable amount of discussion has revolved around the nature of this
dispersion, specifically whether it can be classified as a repulsive Wigner
glass state, characterized by disconnected Laponite particles stabilized by
electrostatic repulsions, or an attractive gel state, in which the particles
form a percolated space-spanning network. The proponents of the Wigner glass
state also conjecture that this system experiences a glass-glass transition
after a period of two days has elapsed since its preparation. In this
commentary, we explore this topic from a rheological point of view analyzing
the published literature and performing new experiments. Aided by additional
evidence from the literature, we propose that rheological behavior
overwhelmingly suggests that an aqueous dispersion of Laponite undergoes sol -
attractive gel transition and remains in the attractive gel state over at least
up to 7 days without undergoing any additional transition. Importantly,
rheology, despite being a macroscopic tool governed by principles of mechanics,
offers profound insight into the microstructure of this particular system. The
corresponding analysis conclusively determines the state of an aqueous
dispersion of Laponite to be an attractive gel.
