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Polymers are an important class of materials with an ever-growing market. For most purposes,
polymers are processed at rates much higher than the inverse of their equilibration time. As a
consequence, polymers often fail to equilibrate within the typical processing timescales,
causing the macromolecules to adopt non-equilibrium conformations. This, in turn, can give
rise to structural, dynamical, and mechanical material properties that differ strongly from those
in thermodynamic equilibrium. However, despite the exciting possibility to control properties
directly by the chosen processing protocol, a rigorous understanding of the processing-property
relations of polymers is still lacking. In this talk, I will discuss our recent experiments [1-3]
yielding quantitative relations between processing pathways, the lifetime of nonequilibrium
states and the resulting mechanical properties of polymer films. Interestingly, such relations
allowed orders of magnitude control over the viscoelastic properties and crystallization kinetics
of polymer films with the same thickness. Towards the end, I will show how an explicit control
over processing pathways could potentially yield novel materials with energy-autonomous and
adaptive functionalities.
1. Sivasurender Chandran and G. Reiter, "Transient cooperative processes in dewetting polymer
melts", Phys. Rev. Lett., 116, 088301 (2016).
2. Sivasurender Chandran, R. Handa, M. Kchaou, S. Al Akhrass, A. N. Semenov and G. Reiter,
"Time allowed for equilibration quantifies the preparation induced nonequilibrium behavior of
polymer films", ACS Macro Lett., 6, 1296, (2017).
3. Sivasurender Chandran and G. Reiter, "Segmental rearrangements relax stresses in
nonequilibrated polymer films", ACS Macro Lett., 8, 646, (2019). |