Team Led By Randall Kamien Advances Nanotechnology Through Liquid Crystal Construction

A team of material scientists, chemical engineers, and physicists from the University of Pennsylvania has made another advance in its effort to use liquid crystals as a medium for assembling structures.

It is an example of a growing field of nanotechnology known as “directed assembly,” in which scientists and engineers aim to manufacture structures on the smallest scales without having to individually manipulate each component. Rather, they set out precisely defined starting conditions and let the physics and chemistry that govern those components do the rest.  

In their earlier studies, the team produced patterns of “defects,” useful disruptions in the repeating patterns found in liquid crystals, in nanoscale grids and rings. The new study adds a more complex pattern out of an even simpler template: a three-dimensional array in the shape of a flower. Because the petals of this “flower” are made of transparent liquid crystal and radiate out in a circle from a central point, the ensemble resembles a compound eye and can thus be used as a lens.  

The team consists of Randall Kamien, Vicki and William Abrams Professor in the Natural Sciences in physics and astronomy; Kathleen Stebe, the School of Engineering and Applied Science’s deputy dean for research and professor in chemical and biomolecular engineering; and Shu Yang, professor in Engineering’s Departments of Materials Science and Engineering and Chemical and Biomolecular Engineering. Members of their labs also contributed to the new study, including lead author Daniel Beller, Mohamed Gharbi, and Apiradee Honglawan.     

When the researchers planted silica beads—polished grains of sand—at the top of a pool of liquid crystal, flower-like patterns of defects grew around each bead. In earlier experiments with different materials, the interface was flat. Here, surface tension on the bead allows the 'petals' to be arranged in a tiered, convex fashion. Because the liquid crystal can interact with light, the entire assembly can function as a lens, focusing light to a point underneath the bead, as with an insect’s compound eye or the mirrors on large telescopes. This type of directed assembly could be useful in making optical switches and in other applications.

Their work was published in Physical Review X and supported by the National Science Foundation, Penn’s Materials Science Research and Engineering Center, and the Simons Foundation.

Read the full story here.

Arts & Sciences News

The Power of Penn Arts & Sciences

On April 12, 2018, the Power of Penn Arts & Sciences fundraising campaign was announced by the Board of Overseers. Launched in conjunction with the University’s Power of Penn campaign, it aims to raise $550 million for the School of Arts and Sciences.

View Article >
2018 Penn Arts and Sciences Dean’s Scholars

Penn Arts and Sciences has named 20 students from the College of Arts and Sciences, the College of Liberal and Professional Studies, and the Graduate Division as Dean’s Scholars. This honor is presented annually to students who exhibit exceptional academic performance and intellectual promise.

View Article >
Joseph Subotnik Named Edmund J. and Louise W. Kahn Term Professor

Joseph Subotnik, Professor of Chemistry, has been named Edmund J. and Louise W. Kahn Term Professor of Chemistry. A theoretical chemist who focuses on electronic processes in the condensed phase, Dr. Subotnik has made key contributions in electronic structure theory, chemical dynamics, and statistical mechanics.

View Article >
Two Penn Arts and Sciences Professors Named Guggenheim Fellows

Charles L. Bosk, Professor of Sociology, and Charles Yang, Professor of Linguistics and Computer Science, have been awarded 2018 John Simon Guggenheim Memorial Foundation fellowships.

View Article >
Ahmad Family Endowment Supports Penn Global Seminars

Hyder Ahmad, W’90, and his family have made a generous gift to establish the Ahmad Family Endowment for Penn Global Seminars in Arts and Sciences.

View Article >
Abraham Nitzan Named Donner Professor of Physical Sciences

Abraham Nitzan, Professor of Chemistry, has been named Donner Professor of Physical Sciences. Nitzan’s research focuses on the interaction of light with molecular systems, chemical reactions in condensed phases and interfaces and charge transfer processes in such environments.

View Article >
2018 Teaching Award Recipients Announced

Steven J. Fluharty, Dean of Penn Arts and Sciences, and Paul Sniegowski, Stephen A. Levin Family Dean of the College of Arts and Sciences, have announced the recipients of the 2018 awards for distinguished teaching in the School.

View Article >
College Graduation Speakers for 2018 Revealed

Angela Duckworth, G’03, GR’06, Christopher H. Browne Distinguished Professor of Psychology, will address the Class of 2018 at the graduation ceremony for the College of Arts and Sciences on Sunday, May 13, 2018. She will be joined by student speaker Helena von Nagy, C’18.

View Article >
Individualized Care Will Become the Standard for Depression Patients

In a new paper for the Annual Review of Clinical Psychology, researchers Robert DeRubeis, Samuel H. Preston Term Professor in the Social Sciences, and Zachary Cohen of Psychology, address precision medicine, also known as customized-care, in the context of treatment for depression.

View Article >
Restoring Vacant Lots Reduces Gun Violence and Crime

In cities across the U.S., about 15 percent of land is considered vacant or abandoned. These areas can foster criminal activity, and urban residents, especially those in low-income neighborhoods, often view vacant land as a threat to their health and safety.

View Article >
Robert DeRubeis: Samuel H. Preston Term Professor in the Social Sciences

Professor of Psychology Robert DeRubeis has been named the Samuel H.

View Article >