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We are interested in developing novel materials synthesis and fabrication methods at the convergence of top-down and bottom-up approaches for directed assembly of complex, multi-functional nano- and microstructured soft materials and their nanocomposites. By coupling of chemistry, fabrication and external stimuli, the Yang lab addresses the fundamental questions at surface-interface in a precisely controlled environment, and study the structure-property relationship.

 

Special interests involve synthesis and engineering of well-defined polymers, gels, colloidal particles, biomaterials, and organic-inorganic hybrids with controlled size, shape, and morphology over multiple length scales, and understand mechanical behaviors and instabilities in soft and geometric substrates. By extending the obtained knowledge, her group seeks to direct patterning and assembly of nano- and micro-objects in solutions and on patterned surfaces to create hierarchical structures. In turn, they explore unique surface, optical, and mechanical properties, and their dynamic tuning. 

 

Recent news

Giant clams inspire Penn duo’s alternative energy research

KirigamiphotoNatural selection in an extreme environment has gradually sculpted the giant clam into an exceedingly efficient farmer; it turns the fierce sunlight in its equatorial ocean home into algae, and those single-celled plants into food.

Two Penn researchers are teaming up to unlock the secrets of this living greenhouse and use it as a blueprint for new materials that harvest solar energy or convert it to biofuel. Learn more

 

(Image courtesy of Alison Sweeney, Penn Physics)

 

 

Penn Researchers Grow Liquid Crystal 'Flowers' That Can Be Used as Lenses

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

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.

Learn more

Gizmag interview

 

 

Nanotech Innovation Keeps Surfaces Clean and Transparent

KirigamiphotoHanging hundreds of feet off the ground to wash a skyscraper's windows or pumping water out to a desert solar array to keep its panels and mirrors clean is more than just a hassle—it's an expensive problem with serious ecological implications.

Researchers at Penn and the spin off company has found a way to solve the problem of keeping surfaces clean, while also keeping them transparent. Learn more

 

 

Penn researchers integrate origami and engineering

KirigamiphotoThe quintessential piece of origami might be a decorative paper crane, but in the hands of an interdisciplinary Penn research team, it could lead to a drug-delivery device, an emergency shelter, or even a space station.

Led by Randall Kamien, a professor in the Department of Physics and Astronomy, the Penn team will collaborate with researchers at Cornell University on the National Science Foundation’s Emerging Frontiers in Research and Innovation Program called ODISSEI, or Origami Design For The Integration Of Self-assembling Systems For Engineering Innovation.

The project draws inspiration from the Japanese art of paper folding, but the Penn team suggested adding a variant of the technique, known as kirigami, in which the paper can be cut as well as folded. Allowing for cuts and holes in the material makes it easier to fold rigid, three-dimensional structures. Read more

(Image courtesy of Randall Kamien, Penn Physics)

 

Penn team making waves with liquid crystals

PNAS LC imageWhile liquid crystals are most known for controlling light propagation in displays, their electro-optic and mechanical anisotropies offer powerful tools to direct the assembly of soft materials. Focal conic domains (FCDs) are some of the first textures identified in liquid crystals, but until recently they were largely geometric curiosities, albeit elegant ones. In the past few years it has become clear that the control of these textures, which are too organized and reproducible to be called defects, can be used to create new surface patterning motifs with novel optical properties, new wetting properties, and the ability to template geometry and topology into the bulk.

An interdisciplinary team at Penn is working with liquid crystals like no researchers have before, opening the door for new applications in displays, lenses, sensors, and even nano-manufacturing.  Read more

(Art courtesy of Felice Macera, Daniel Beller, Apiradee Honglawan, and Simon Čopar)

Research topics:

  • Control of wetting, adhesion and bioadhesion on topographic polymer surfaces
  • Templating topological defects in liquid crystal molecules using gemoetric substrates
  • Dynamic tuning of optical properties using geometrically patterned responsive materials
  • Nano/micropatterning of periodic 2D and 3D structures from polymers and hybrid materials
  • Harnessing elastic instabilities in (patterned) polymer gels