Solid or liquid?

On March 3rd, 2023, Postdoc Rob Wagner and Ph.D. candidate Zhongtong Wang, in conjunction with the Cornell Center for Materials Research, attended Dryden Elementary School to teach 3rd-grade students about the phases of matter, and viscoelastic materials. In this interactive lesson designed by Rob, Rob and Zhongtong used hands-on demonstrations spanning from rubber bands and maple syrup, to silly putty, ooblek, and shaving cream to teach the kids about the principles of elasticity, viscosity, and what happens when materials can have both! The lesson ended with a set of video demonstrations and open Q&A pertaining to some of Rob’s Ph.D. research on the mechanics of fire ant rafts, thus highlighting the creative ways researchers may use traditional material science concepts in the exploration of rich, yet widely untapped dynamic, active, and living materials. By allowing the students to make observations, postulate hypotheses, and then openly discuss the root causes of properties in these unusual materials, Rob and Zhongtong sought to spur curiosity, scientific reasoning, and a broader interest in STEM amongst these promising young minds!

Paper on modeling elastomers with ionic bonds and entanglements out in Mechanics of Materials

Dynamic crosslinks and entanglements play a significant role in tuning mechanical properties of elastomers and gels. In our recent paper in the journal of Mechanics of Materials, we report a continuum modeling framework that considers these two mechanisms for adding toughness and strength to polymers – ionic bonding and entanglements. This theoretical study led by Zhongtong Wang investigates these mechanisms in the context of bulk polyelectrolyte mechanical properties. This work firstly establishes the constitutive model that couples entanglement evolution with the ionic crosslink effects and ionic bonds provide strength and dissipate energy without stiffness loss. This theoretical framework could direct the design of customized materials for various applications.  

ELMI website updated!

The Engineered Living Materials Institute website is now live. Please check out our new institute home:

Congratulations to Nikola!

Congratulations and good luck to Nikola Bosnjak for his new job at Nike!

Congrats to Zhongtong Wang!

Congratulations to mechanical engineering PhD candidate Zhongtong Wang for passing his A-exam earlier this week! Zhongtong’s PhD will be on “Constitutive Modeling of Polymers and Polymer Composites with Dynamic Bonds.”

Silberstein lab goes to IMECE

Mechanical engineering PhD students Max Tepermeister and Zhongtong Wang, and MS student Jinyue Dai all presented at ASME’s International Mechanical Engineering Congress and Exposition in Columbus, Ohio last week.

Publication on ionically crosslinked elastomers is out in Soft Matter

Incorporation of reversible crosslinks into polymers is an effective approach for tailoring their mechanical properties and to realizing behavior like self-healing, shape memory, and pH sensitivity. Among various reversible crosslink types, ionic bonds are particularly interesting because of their biocompatibility, saloplasticity, and relevance for energy conversion technologies. Understanding the structure-function relationship of such polymers is important for future development of advanced materials. In our latest paper, led by PhD candidate Hongyi Cai, we address this question by designing and characterizing a series of highly stretchable elastomers inspired by polyelectrolyte complexes. We demonstrate how ionic bonds formed among polymer chains strengthen the elastomers and also help them recover.

Welcome to new MMD lab members!

Welcome to new MMD lab members: postdocs Si Chen and Robert Wagner and PhD candidate Ellen van Wijngaarden! And good luck to MMD alums Srikar Srivatsa and Xinyue Zhang with their new awesome west coast careers!

Congratulations Srikar!

Congratulations to now former graduate student Srikar Srivatsa for successfully defending his Masters thesis last week!

Modeling Polymer Chains

MMD lab graduate Michael Buche just published work started in his PhD thesis in Physical Review E. “Freely jointed chain models with extensible links” presents how to derive asymptotically correct analytical expressions for the force-stretch relationships for polymer chains with extensible bonds utilizing statistical thermodynamics. This work was co-authored with Prof Silberstein and fellow Cornell Theoretical and Applied Mechanics graduate Scott Grutzik.