The projects in our labs share a common goal: To design “intelligent” materials with tunable dynamic responses by manipulating the interplay between weak (reversible) colloidal-range forces and the often cooperative dynamics of polymeric chains.
While it may come as a surprise that weak colloidal-range forces, contributing only a few kT per each reversible physical bond, can be important in materials development, it turns out that they dominate many familiar systems. One prominent example is living tissue, which is comprised of a hierarchy of intra-molecularly associated and inter-molecularly bound molecules, generating structure at different lengthscales, and responses at different timescales.
Besides their importance in biology (they are responsible for protein folding, they orchestrate the precise recognition between receptors and their ligands), reversible bonds play important technological roles: Competing colloidal forces (Van der Waals, electrostatics, hydrophobic interactions, hydrogen bonding) control copolymer and surfactant self assembly into micellar and lamellar phases; they drive polymer adsorption, they promote colloidal stability or flocculation; they facilitate lubrication and regulate some classes of adhesion; and they dominate the rheological properties of complex fluids. Colloidal-range potentials often present maxima which contribute activation energies to kinetic processes. When combined with the topological constraints and cooperativity inherent to polymers, the tuning of colloidal potentials weaves an intricate fabric of dynamic possibilities for materials design and processing.
While one research thrust within the Santore group is the development of certain classes of biomimetic materials, our broader philosophy is that many dynamically interesting and useful materials, beyond those with obvious bio-interface or medical applications, can be designed based on an understanding of colloidal and biomolecular interactions. These materials include some with obvious structures and others, though less organized, that exhibit tunable dynamic response. Part of the research in our group aims to develop a fundamental understanding of dynamic behaviors, while other programs more directly target the development of new materials. Students in the Santore lab gain an appreciation for the full spectrum from fundamental polymer and colloidal physics to material design.
Research in the Santore group focuses on polymer and colloid behavior at interfaces, with experimental projects targeting a range of applications and technologies, from the extremely fundamental to the highly applied, and from improvements to existing processes to the development of new materials and processes which are highly evolved. Activities in our labs involve the manipulation of molecules by adsorption, self assembly, flow, and application of pico- and nano-Newton forces with AFM or micropipettes. Because polymer chemistry, surface chemistry, and polymer architecture must be chosen appropriately to achieve the desired molecular interactions and structure, our projects employ custom molecules and custom surface treatments. Researchers in the Santore group are therefore involved in a moderate amount of wet chemistry: Rather then inventing new synthetic routes, we employ existing chemistries or undertake collaborations to obtain molecules and surfaces of carefully designed chemistry and architectures. With the molecules and surfaces in hand, the important science of studying and manipulating their interactions, structure, and dynamics follows.
Specific research areas include: