Extreme thermodynamics with polymer gel tori: Harnessing thermodynamic instabilities to induce large-scale deformations
Year: 2018
Type: article
Abstract: When a swollen, thermoresponsive polymer gel is heated in a solvent bath, it expels solvent and deswells. When this heating is slow, deswelling proceeds homogeneously, as observed in a toroid-shaped gel that changes volume while maintaining its toroidal shape. By contrast, if the gel is heated quickly, an impermeable layer of collapsed polymer forms and traps solvent within the gel, arresting the volume change. The ensuing evolution of the gel then happens at fixed volume, leading to phase separation and the development of inhomogeneous stress that deforms the toroidal shape. We observe that this stress can cause the torus to buckle out of the plane, via a mechanism analogous to the bending of bimetallic strips upon heating. Our results demonstrate that thermodynamic instabilities, i.e., phase transitions, can be used to actuate mechanical deformation in an extreme thermodynamics of materials.
Source: Physical review. E
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
Awards: Materials Research Science and Engineering Centers, G1212418557, G1337647245, G2229954460, G2301255353, G2432923657, G2867976162, G2916140176, Topics in Classical and Quantal Soft Matter, Crystallization and glass formation in colloidal-hydrogel suspensions, G4644544412, G4711322603, G5268905743, G6599444349, CAREER: Mesoscale Modeling of Soft Polymer Networks, Programs on Critical Problems in Physics, Astrophysics and Biophysics at the Aspen Center for Physics, Graduate Research Fellowship Program (GRFP), G837711380, G8387009440
OpenAlex ID: W2810222669