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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. 

 

Check out our kirigami blog

Center for Analyzing Evolved Structures as Optimized Products: Science and Engineering for the Human Habitat (AESOP)

Women in Nanoscience Blog

 

Recent news

Powering the Future with Giant Clams

colloids in cylinders

In 2014, Shu Yang, of the Materials Science and Engineering, joined School of Arts and Sciences’ biophysicist Alison Sweeney on an unusual quest. Backed by a NSF INSPIRE grant for bold, interdisciplinary research, the duo aimed to unlock the solar-powered secrets of the giant clam. Read more.

Continue reading at The Atlantic.

and related reading at Mimicking Giant Clams to Enhance the Production of Biofuel.

 

 

 

 

Making complex 3-D surfaces with 2-D sheets

colloids in cylindersJiffy pop, an aluminum foil pan full of popcorn kernels and oil, is a staple of camping trips. Because of the way the pan is designed, when placed above an open campfire the kernels expand the aluminum top as they heat and pop, ultimately resulting in a bag of popcorn. The aluminum is lined with ridges, which unwind, allowing it to expand into a spherical shape.

Now, researchers at the University of Pennsylvania have used a similar concept to design two-dimensional sheets of a rubber-like material called liquid crystal elastomer capable of transforming into complex three-dimensional geometries, such as a human face, with heat. This has countless technological applications in areas such as flexible electronics, metamaterials, aerospace, medical devices, and drug delivery. Read more.

(Image credit: Felice Macera for arstic rendering).

 

Making Atomic thin sheets stand up for better energy storage

colloids in cylinders

When it comes to cell phones, there are fewer things more frustrating than a short battery life. Researchers at the University of Pennsylvania and Drexel University reported a novel and scalable approach to prepare electrodes from atomic thin 2D nanosheets in the vertical orientation via self-assembly (see publication in Nature). The method marries soft matter assembly and functional hard nanomaterials by creating a coherent and long-range ordered liquid crystal phase of 2D sheets of titanium carbide, Ti3C2, a member of the MXene family. The resulting electrode films show rapid ion diffusion in thick films, retaining almost 100 % of the capacitance after 20,000 cycles of galvanostatic cycling at a rate of 20 A/g, and nearly thickness-independent (up to 200 micrometers, or 0.2 mm). Read more.

 

Mimicking Giant Clams to Enhance the Production of Biofuel

colloids in cylindersAlison Sweeney of the University of Pennsylvania has been studying giant clams. She refer to the clams as “solar transformers” because they are capable of absorbing bright sunlight at a very high rate and scattering it over a large surface area. When the light is distributed evenly among the thick layer of algae living inside the clam, the algae quickly converts the light into energy.Working with Sweeney, the Yang lab devised a method of synthesizing nanoparticles and adding them to an emulsion — a mixture of water, oil, and soapy molecules called surfactants — to form microbeads mimicking the iridocytes, the cells in giant clams responsible for solar transforming. Read more

 

 

 

 

 

Creating Ultra-lightweight Materials That Expand With Heat

colloids in cylindersWhen it comes to taking up room without adding too much weight, the bubble can’t be beat. Because they are mostly air, they’re ultra-lightweight and can expand to fill any given space.

Researchers at the University of Pennsylvania and the Korea Institute of Science and Technology (KIST) found a way to exploit these properties of bubbles to create “microbombs” that expands with heat to form “microclusters,” which fit themselves to fill their physical confinement. When expanding to large volumes and filling spaces, microclusters become extremely lightweight with soft and adaptable boundaries. Using this material, the researchers hope to improve heat and sound insulation, electromagnetic interference shielding and a process called jamming that has been used in robotics and materials design. Read more.

 

Surprising Insights Into the White Spots on Butterfly Wings

colloids in cylinders

A collaboration between biologists and materials scientists at the University of Pennsylvania is yielding new insights into the wings of the “skipper butterfly” in the Costa Rican rainforest. What they learn could lead to technological advancements in systems ranging from power-efficient computer displays to sensors to energy efficient buildings, windows and vehicles. Read more

 

Colloids: Personal space matters

colloids in cylinders Colloids are useful models for understanding the structure and behaviour of atoms and molecules. Indeed, colloidal phases are governed by many of the same forces that control the interactions between smaller particles. When colloids are confined within a space, the interactions at play are often not rationalizable simply in terms of free-energy minimization. In cylindrical spaces, colloids form particularly interesting assemblies. Read more

 

Nanotech garment will gather health information through sweat

nanoshirt Wearable technology requires materials that are both flexible and functional, so developers often look to polymers or to make harder materials as thin as possible. “So we’re taking inspiration from clothing” to make a new kind of wearable health tracking device that gathers information from its wearer through his or her sweat.

Instead of just wicking sweat away, the team's yarn will be able to chemically analyze its contents and change color accordingly. Read more

 

Shu Yang Receives Heilmeier Research Award

Shu Yang, Professor in the Department of Materials Science and Engineering with a secondary appointment in Chemical and Biomolecular Engineering, has been named the recipient of the 2015-16 George H. Heilmeier Faculty Award for Excellence in Research for "pioneering the synthesis and fabrication of responsive nano- and micro-structured soft materials." Read more

 

Penn engineers design material that could help diagnose concussions

The precise link between concussions in sports, especially at the youth level, and traumatic brain injurie by soldiers is still being explored. Unfortunately, unlike a broken bone or a torn ligament, concussions are invisible and tricky to diagnose. Tthe Penn team in collaboration with Gang Feng’s group at Villanova University and Jie Yin’s group at Temple University has developed a polymer film-based sensor that changes colors depending on how hard it is hit. The goal is to someday incorporate this material into protective headgear that could give an early warning sign of a concussion. Read more

 

Penn research team develops ‘smart’ window

KirigamiphotoCommonplace as they are, windows are an important piece of technology. Beyond architectural aesthetics, a building’s ecological footprint depends heavily on how its internal light and heat are managed. With this in mind, researchers from around the world are trying to make windows “smarter” by tailoring their properties to be more responsive and finely tuned to changing needs.

Read more

Also featured in Y-prize competition 2016

 

 

 

 

 

 

 

 

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)

 

Research topics:

  • Analyzing Evolved Structures as Optimized Products (AESOP): Science and Engineering for the Human Habitat
  • Control of wetting, adhesion and bioadhesion on topographic polymer surfaces
  • Templating topological defects in liquid crystal molecules using gemoetric substrates
  • Foldable, buildable materials guided by lattice kirigami (Check out our kirigami blog)
  • 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