CBES Investigators

Monica Olvera de la Cruz

Pablo Agustin Vazquez-Montejo

Postdoctoral Fellow
Physics

Joshua Dempster

PhD Candidate
Applied Physics

Jack Edelbrock

PhD Candidate
Materials Science and Engineering

Honghao Li

PhD Candidate
Chemistry

Shuangping Liu

PhD Candidate
Materials Science

Chase Brisbois

Graduate Student
Materials Science and Engineering

Research Overview

CBES research in the Olvera de la Cruz group focuses on three main themes:

Polyelectrolyte Gels and Membranes

Polymeric networks of charged chains (polyelectrolytes) have important applications in tissue engineering and in energy storage and conversion. Their physical properties are dictated by the various interactions and more notably by the competition of electrostatics and elasticity.  For example, when two like-charge hydrogel slabs are brought into contact, they tend to stay apart and create a polymer free solvent layer as a result of the osmotic pressure of their counterions that maintain electroneutrality. Thus, a double-hydrogel system can be used to minimize the friction between two relatively moving surfaces similar to those in connective tissues of mammalians. Our group focus on understanding and optimizing polyelectrolytes for energy storage and conversion by using extensive course-grained molecular dynamics simulation and theoretical approaches.

Snapshots of the hydrogel bilayers taken from coarse-grained simulations. Hydrogels are modeled as defect-free cubic lattices of polyelectrolytes with various sizes and charge fraction; a) Underformed hydrogels and schematic definition of the gap, b) Hydrogels in deformed state, c) 3-D representation of hydrogel bilayers.

 

The Olvera group is further focused on investigating pH responsive organelles. Using mean-field simulations we study the effect of electrostatics on the equilibrium shape of solution of membranes. In particular, we consider the case membranes with constant transfer of ions from or to the solution. The chemical equilibrium regulating this charge can be adjusted using external factors such as, the pH of the solution, as well as the shape of the membrane itself. In addition, the diversity of available materials and the novel ways of performing electronic tasks has inspired research towards stretchable, transparent, 3d- printable, and biodegradable devices. This could fundamentally change the way we perceive or interact with electronics in our daily lives. Olvera de la Cruz is designing soft-electronic structures.

Self-replication

Decades of effort have achieved considerable success in molecular self-replication, but colloidal self-replication has proven more challenging. Sustained exponential growth at colloidal scales can be achieved through cycles of driving and dissipation, which require continuous control of some local environmental variable. Olvera de la Cruz group proposes using magnetic colloids to create a realizable system of self-replication. Binding sites on the colloids allow them to form dimers, which serve as templates for replication. Colloid clusters are periodically dissolved by a drive consisting of a strong external magnetic field. The Olvera de la Cruz group identified a low-error regime in which dimers exhibit almost pure exponential growth. Future work will focus on extending the system to replicate more complex templates.