After a brief introduction to soft condensed matter physics, I will describe colloid experiments that create traditional and less-traditional phases of matter and facilitate exploration of transitions amongst these states of matter. Many of these observations are relevant to the behaviors of both hard and soft materials. In the remaining time, I will describe experiments with liquid crystals that reveal remarkable “almost biological” shape transformation behaviors and, in a different vein, morphological transformations of twist disclinations in the orientationally ordered nematic phase as the system is cooled into the smectic phase, which has both orientational and partial translational order.
Arjun G. Yodh is the James M. Skinner Professor of Science and Chair of the Department of Physics and Astronomy at the University of Pennsylvania (Penn). He was recently Director (2009-2020) of Penn’s Materials Science and Engineering Center (NSF-MRSEC) and its associated Laboratory for Research on the Structure of Matter (LRSM). Yodh graduated from Cornell University (1981) with a B.Sc. in Applied & Engineering Physics. He obtained his Ph.D. from Harvard (1986) working with Tom Mossberg and then worked as a post-doc at AT&T Bell Laboratories with Steven Chu and Harry Tom. Yodh joined the physics faculty at Penn as an Assistant Professor in 1988 and has remained at Penn since then. Areas of his ongoing research include: Soft Condensed Matter, which explores the physics of materials such as colloids and liquid crystals, and Biophotonics, especially functional imaging/monitoring of living tissues with diffusing light. Most of his experiments involve optics, including diffuse optics and spectroscopy, optical microscopy/micromanipulation, nonlinear optics, and light scattering. He was awarded the 2021 Feld Biophotonics Prize of the Optical Society of America (now Optica) and the 2024 Penn Provost Award for Distinguished PhD Teaching and Mentoring. In addition to mentoring more than one hundred PhD students and post-doctoral associates, Yodh has made significant contributions to education and outreach activities at Penn, for example leading partnerships with the University of Puerto Rico and research experience programs for undergraduates and high school students/teachers.