Colloidal materials occupy a central position in modern soft matter science, linking physics, chemistry, and materials engineering. This course provides a unified treatment of the fundamental forces that govern colloidal stability and assembly—van der Waals, electrostatic, depletion, steric, and DNAmediated interactions—and examines how these determine structure and dynamics in dispersed systems. Particular emphasis is placed on electrokinetic phenomena, including the formation of the electric double layer, zeta potential, and their roles in electrophoresis and electroosmosis.
The course explores how these interactions produce equilibrium and nonequilibrium phases, from liquids and crystals to gels and glasses, and how shape anisotropy, patchiness, and nonconvex geometry lead to directional, lock-and-key, and entropic binding. Later topics introduce methods for colloid synthesis and surface modification, optical and photonic properties, and emerging areas such as active and responsive colloids.
By connecting physical principles with experimental and computational approaches, the course provides a framework for understanding, designing, and controlling complex colloidal materials.

By the end of the course, students will be able to:
1. Explain the balance of attractive and repulsive forces in colloidal systems (DLVO theory, screened Coulomb, steric, and depletion interactions).
2. Describe electrokinetic phenomena including the formation of the electric double layer, measurement and significance of zeta potential, and applications to electrophoresis and electroosmosis.
3. Describe DNA-mediated, patchy, and shape-programmable interactions that lead to directional assembly.
4. Interpret phase diagrams and understand colloidal crystallization, gelation, and glass transitions.
5. Recognize the role of particle anisotropy and nonconvex geometry in lock-and-key and diamond-like assembly.
6. Understand synthetic methods for organic and inorganic colloids and their surface modification.
7. Relate optical properties of colloidal materials to scattering, photonic bandgaps, and structural color.

Undergraduate-level Physical Chemistry

• P. C. Hiemenz and R. Rajagopalan, Principles of Colloid and Surface Chemistry, 3rd ed., CRC Press (1997).
• J. Israelachvili, Intermolecular and Surface Forces, 3rd ed., Academic Press (2011).

L1. Introduction to Colloidal Materials. Colloids in nature and technology; size and time scales; Brownian motion and diffusion; overview of interparticle forces.
L2. DLVO Theory: Classical Interactions. van der Waals attraction and screened Coulomb repulsion; grafted-polymer steric repulsion; colloidal stability and aggregation kinetics.
L3. Electrokinetics and Zeta Potential. Structure of the electric double layer; Poisson–Boltzmann theory and surface charge regulation; definition and measurement of zeta potential; electrophoresis, electroosmosis, and streaming potential.
L4. Beyond DLVO: Depletion and DNA-Mediated Forces. Entropic depletion forces from polymers; Asakura–Oosawa model; tunable attractions via nonadsorbing macromolecules and DNA linkers.
L5. Self-Assembly and Phase Behavior. Thermodynamic versus kinetic control;nucleation and growth; coexistence curves, gels, and glassy states; templated and epitaxial growth; energy landscapes.
L6. Patchy and Directional Interactions. Concepts of valence and directional bonding;DNA-coated colloids and patchy particles; selective binding and design rules for assembly.
L7. Nonconvex and Interlocking Colloids. Shape-mediated interactions, lock-andkey binding, and mechanical entanglement; examples from tetrahedrally lobed and diamond-forming systems; connection to geometric frustration and entropic patchiness.
L8. Colloid Synthesis and Formation. Emulsion and dispersion polymerization for latex colloids; Stober and sol–gel synthesis for silica and titania. Surfactant systems:micelles, microemulsions, and emulsions.
L9. Optical Properties of Colloidal Materials. Light scattering, photonic crystals, plasmonic coupling, and structural color; colloidal crystals as model photonic solids.
L10. Emerging Topics and Integration. Active and responsive colloids; integration of shape, surface, and optical properties; summary discussion.