APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022;
Chicago
Session Z42: Recent Developments on the Physics of Polymer Adsorbed Layers
11:30 AM–2:30 PM,
Friday, March 18, 2022
Room: McCormick Place W-375A
Sponsoring
Units:
DPOLY DPOLY DSOFT GSNP
Chair: Teresa Tschirner, IFW Dresden
Abstract: Z42.00001 : Accessing low energies in glasses with large free interface
11:30 AM–12:06 PM
Abstract
Presenter:
Daniele Cangialosi
(Donostia International Physics Center, San Sebastian, Spain)
Author:
Daniele Cangialosi
(Donostia International Physics Center, San Sebastian, Spain)
Collaboration:
Daniele Cangialosi
In nature, the kinetics of approach to equilibrium in non-equilibrium systems can be either accelerated or retarded depending on environmental conditions. This is the case of non-equilibrium glasses; where it was shown that, increasing the amount of free interfacial area, i.e., decreasing the length scale of nanostructuring, accelerates approach to equilibrium, the so-called "physical aging". This acceleration is evident in the efficiency of maintaining equilibrium of these glasses, resulting in significant glass transition temperature (Tg) suppression. Importantly, moderate length scales of nanostructuring, acceleration of physical aging takes place with essentially bulk-like equilibrium properties. In this contribution, I will first introduce how calorimetric techniques, including fast scanning calarimetry, can be exploited to the charcaterize the kinetics of evolution of a glass thermodynamic state. Subsequently, by characterizing the enthalpy evolution during physical aging, I will show that mild enhancement of the free interfacial area may result in massive decrease of the glass energy toward the equilibrium liquid line. Finally, the ability of nanostructured glasses to equilibrate is exploited in polystyrene films and poly-t-butyl styrene spheres. In both cases, aging way below Tg for times not exceeding some days allows attaining glasses whose entropy equals that of the corresponding crystal. This outcome is interpreted as a signature of the existence of the ideal glass. Glasses exhibiting the thermodynamic state of the ideal glass show vibrational density of states (VDOS), as measured by inelastic neutron scattering (INS), resembling that of crystals. Specifically, suppression of the boson peak, normally observed in standard glasses, is observed. These results are discussed in the framework of the link between the macroscopic thermodynamic state of glasses and their vibrational properties.