Research Projects
Soft materials are irreplaceable in applications where large reversible deformations are needed. These include elastomers for engineering (e.g. rubber, soft robotics, wearable electronics) and hydrogels for life sciences (e.g., artificial tissues, soft prosthetics). Although mechanical strength is only essential for some applications, poor fracture toughness, durability, and lifetime remain important limitations. Our laboratory uses molecular design as a tool to fundamentally understand the structure-property relationships to design the soft, tough, and processable (i.e., recyclable) materials necessary for a more energy-efficient and healthy society.
Recycling ElastomersSpurred by the discovery of vulcanization by Goodyear (1840), elastomers have become essential in widespread engineering applications such as vehicle tires and seals. Given that their mechanical properties result from their chemically cross-linked structure, these materials can neither be thermally nor solvent processed and have a significant environmental footprint. We seek to demonstrate novel strategies for recycling elastomers through molecular design of polymer chains that can reversibly depolymerize upon exposure to an external stimulus.
Lifetime Prediction of Soft MaterialsAlthough elastomers are irreplaceable in a myriad of applications, they are often over-engineered due to a poor prediction of their lifetime under service conditions (e.g., gas separation membranes, pressure seals). The challenge lies on the inability to detect low levels of damage where there are no significant changes in the elasticity, plasticity, or other properties readily measured with a state-of-the-art mechanical test. This early stage of fracture precedes nucleation and propagation of a crack and is representative of an important period of the material lifespan. We will design elastomers tagged with probes that enable non-destructive visualization of damage prior failure. These materials will serve to gain insights into crack initiation, crack propagation, and catastrophic failure in a range of industrially relevant loading-configurations (e.g., cavitation, environmental stress cracking).
Fatigue Fracture of Tough HydrogelsMultiple network (MN) hydrogels are promising for biomedical applications due to the high fracture toughness enabled by covalent bond scission in a so-called filler and pre-stretched network. Nonetheless, their performance in fatigue remains poor presumably due to changes in the energy dissipation mechanisms at low deformations and large frequencies. We will engineer MN hydrogels to understand this fundamental problem while developing novel materials that are stiff, tough, and with unprecedented lifetime.
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Tomas Saraceno in his installation “Algor(h)i(y)thms” at the Palais de Tokyo in Paris. Participants are invited to play the work by gently plucking or sliding their fingers up and down the strings. This is an immersive macroscopic experience to the architecture of a soft polymer network. Photo by Julie Glassberg for The New York Times