Monica Olvera de la Cruz, Professor
Department of Materials Science and Eng
Northwestern University

E-mail: m-olvera@northwestern.edu
Phone: 847-491-7801

BA, physics, 1981, Universidad Nacional Autonoma de Mexico
PhD, physics, 1984, Cambridge University

National Institute of Health FIRST Award, 1988-93
David and Lucille Packard Fellowship for Science and Engineering, 1989-94
Alfred P. Sloan Fellowship, 1990-92
NSF Presidential Young Investigator Award, 1990-95
Scientific member, Service de Chimie MolŽculaire, Commissariat a lÕƒnergie Atomique (CE-SACLAY), France, 1995-97

Research Areas
The Olvera de la Cruz group studies the organization mechanism and the structure of complex macromolecular systems. In particular, they study the self-organization of polyelectrolytes and copolymers into complex structures. In the area of polyelectrolytes, they develop models to determine the conformation and the effective charge of nano-aggregates of macromolecules driven by electrostatics in different ionic media. Many synthetic and biological polyelectrolytes, for example, undergo two structural transitions upon increasing the concentration of multivalent salt or molecules [1]. The stretched chains in low monovalent salt solutions collapse into nearly neutral compact structures when the density of multivalent salt approaches that of the monomers.[2] With further addition of multivalent salt the chains re-dissolve with a reduced or an inverted charged determined by the size and charged of the condensing particles.[3] Glassy, almost crystalline structures in micro- and mesoscopic charged systems are important in many other biological and synthetic systems, including in spherical polyelectrolytes.[4]

This group also studies nanostructures in copolymers systems.[5] Recently they have studied the non-centrosymmetric structures formed by nano-aggregates of self-assembled triblock molecules consisting of a crystallizable rod segment, a flexible spacer and a bulky coil block .[6] It was found that the ground state conformation of a model with competing dipole-dipole and short range interactions exactly. These results suggest that due to surface effects, films of finite thickness have a non-zero macroscopic polarization, and the polarization per unit volume appears to be a function of film thickness.

The dynamics of multicomponent incompatible complex fluids are studied numerically in this group. Recently, they included hydrodynamic flow in the study of the diffusion driven phase separation of ternary systems into two and three phases.[7]

Related Publications
1.E. Raspaud, M. Olvera de la Cruz, J.-L. Sikorav, F. Livolant, Biophys. J. 74, 381 (1998).

2. Solis, F. J.; Olvera de la Cruz, M., J. Chem. Phys. 112, 2030 (2000)

3. Solis, F. J.; Olvera de la Cruz, M., EPJ direct E1, 1 (2000)

4. Solis, F. J.; Olvera de la Cruz, M., "Attractions between charged colloidal spheres mediated by correlated distributions of absorbed mobile ions" (http://xxx.lan1.gov/abs/cond-mat/0010065).

5. M. Olvera de la Cruz "Phase Segregation in Copolymer and Homopolymer Multi-Component Mixtures" in "Structure and Properties of Multi-Phase Polymeric Materials", Eds. T. Araki, Q. Tran-Cong and M. Shibayama, Marcel Dekker, Inc., (1998).

6. Sayar, M.; Solis, F. J.; Olvera de la Cruz, M.; Stupp, S. I. "Competing Interactions Among Supramolecular Structures on Surfaces" Macromolecules 33, 7226 (2000).

7. Smith, K.A.; Solis, F. J.; Tao, L; Thornton, K; Olvera de la Cruz, M., Phys. Rev. Lett. 84, 91 (2000). Phys. Solis, F. J.; Olvera de la Cruz, M , Rev. Lett. 84, 3350 (2000).