The LRSM topological insulator (TI) seed is investigating how the connectivity of electronic bands in momentum space can be used to topologically classify insulators and semimetals. The theory of topological band structures has been generalized beyond TIs to include topological semimetals, including Weyl semimetals, Dirac semimetals and other symmetry protected topological states.

‘Living Smectics’ are being studied by a Physics PhD student, Stephanie Majkut, with Andrea Liu helping in theory.

The LRSM has organized a free, four week summer program for local high school students interested in materials science and engineering since 1993. Typically 24-28 students, usually juniors but occasionally well qualified sophomores, are accepted. Students are drawn from schools in the Delaware Valley within easy commuting distance of the LRSM. The program consists of lectures on materials, a computer lab, experimental labs, and field trips to both industrial and Penn facilities.

This year, we collaborated with Penn’s Center for Technology Transfer (CTT) on a discussion panel "How to Start a Materials-based Company." CTT is in charge of transferring inventions and innovative knowledge to outside organizations for the benefit of society. The panel, geared mainly towards graduate students, focused on starting a materials science based company. Three CEOs from the Delaware Valley discussed their startup experience, and two experts, who assist new companies, provided information on available resources for entrepreneurs.

Semiconductor nanocrystals are sensitive to air and solvents, which hinders wet-chemical processing under ambient conditions. This problem has limited the scaling of nanocrystal device dimensions and large-scale device integration achievable by  conventional processing. We demonstrated a simple, in-situ recovery route using indium metal as a chemical agent which upon thermal activation is triggered to diffuse and repair the damage introduced by chemical and environmental exposure that degrade the electronic properties of semiconductor NC thin films and their devices.

The mechanical failure of amorphous systems is not well understood, but recent work by Liu and co-workers suggests that low-frequency vibrational modes are concentrated in localized regions, or “soft spots,” that are prone to rearrange. Yodh and Liu experimentally studied the nature of soft spots in crystalline and amorphous packings of colloidal spheres.  In crystals  [1], they found soft spots to be concentrated on topological defects such as grain boundaries and dislocations that are well known to serve as flow defects in crystals.

Dendrimers are highly branched molecules. Amphiphilic glycodendrimers have been synthesized for the first time. These macro-molecules have tunable carbohydrate head groups and hydrophobic tails. The precise architecture of the dendrimers facilitates assembly of precise structures, including vesicles (glycodendrimersomes). These novel vesicles display biological activity, including fusion and coalescence in response to lectins.

  The term “defect” suggests something to be avoided.  However, our team has developed an extensive toolkit to control the locations, shapes, and detailed geometry of so-called topological defects in liquid crystals, the same sorts of materials used in the $100bn/year display industry.  Our goal is to harness these defects to use them as cues for further directed- and self-assembly, as lenses and optical elements, and as building blocks for hierarchical materials.