ESPCI web site
Ellie Laura Porath
Viscoelasticity of PDMS Vitrimers and Active Soft Gels
Tunable soft polymeric materials have applications from soft robotics, adhesives, 3D printing, and reusable plastics. The first part of the talk will focus on dynamic polymer networks (specifically vitrimers) of polydimethylsiloxane backbone crosslinked with various boronic esters. Fundamental characterization of the rheological effects of mixing the crosslinkers of varying kinetics in the PDMS networks could inform applications for vibration and sound damping materials. Due to the hydrophobic and dynamic behavior of these PDMS vitrimers, the material was also made into ultra-thin vitrimer coatings, which were able to self-heal abrasions and withstand condensation for weeks.
The second part of the talk will focus on soft hydrogels and the rheological effect of active particles on the network during gelation. Swimming Janus particles vary the viscoelasticity of the hydrogel and exert a mechanical pressure from within. By varying the amount of the fuel (hydrogen peroxide) added, the motility can be slightly tuned, thereby also affecting the modulus and viscosity of the network, by displacing bonds from forming or by also densifying regions of polymer. These two stories show how tunability in chemistry or activity can lead to broader applications for the field of soft polymer materials.