Some open challenges in polymer physics

Three subjects in polymer and soft matter physics are outlined in the present article. The first relates to concepts of an ideal glass transition. We describe work on ultra‐stable glass, either a 20‐million‐year‐old amber or a vapor deposited amorphous fluoropolymer, which examines the temperature d...

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Bibliographic Details
Published in:Polymer engineering and science 2022-05, Vol.62 (5), p.1325-1355
Main Authors: McKenna, Gregory B., Chen, Dongjie, Mangalara, Satish Chandra Hari, Kong, Dejie, Banik, Sourya
Format: Article
Language:English
Subjects:
Analysis
cyclic macromolecules
DNA
fictive temperature
Fluoropolymers
glass and glass transition
Glass transition temperature
Heterogeneity
Hole burning
ideal glass
LAOS
macromolecular rings
Macromolecules
mechanical spectral hole burning
molecular rheology
nonlinear viscoelasticity
Physics
polymer dynamics
Polymer physics
Polymers
Properties
Rheological properties
Rheology
Temperature
Temperature dependence
ultrastable glass
Vapor deposition
Viscoelastic materials
Viscoelasticity
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Summary:Three subjects in polymer and soft matter physics are outlined in the present article. The first relates to concepts of an ideal glass transition. We describe work on ultra‐stable glass, either a 20‐million‐year‐old amber or a vapor deposited amorphous fluoropolymer, which examines the temperature dependence of the dynamics in a window between a low fictive temperature and the glass transition temperature. From this “finesse” of the problem of the geological time scales in sub‐glass temperature systems strong evidence that the divergence of the relaxation times at finite temperature from WLF‐types of extrapolation is not correct. The second topic is polymer nonlinear viscoelasticity as it relates to dynamic heterogeneity. We show results from mechanical hole burning experiments that suggest that dynamic heterogeneity arises from the nature of specific relaxation mechanisms rather than heterogeneous changes in, for example, the fictive temperature. Included is a discussion of large amplitude oscillatory shear testing and how it relates to characterization of nonlinear viscoelastic materials. The last topic addressed is the rheology of circular macromolecules. Here, we take a historical perspective and describe important new results from several laboratories that seem inconsistent. New works from our own studies on circular DNA are also discussed.
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.25938