Tunability of Free Volume and Viscoelastic Damping of Thiol–Ene Networks Deep in the Glassy State

Tunability of Free Volume and Viscoelastic Damping of Thiol–Ene Networks Deep in the Glassy State

Model thiol-click glassy networks with low shrinkage and sharp glass transition temperatures are studied down to cryogenic temperatures to relate viscoelastic damping to changes in microscopic hole volume. Networks synthesized by polymerization of divinyl sulfone with pentaerythritol tetrakis­(3-mer...

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Bibliographic Details
Published in:Macromolecules Vol. 51; no. 7; pp. 2564 - 2571
Main Authors: Anthamatten, Mitchell, O’Neill, Sean W, Liu, Dezhi, Wheler, Tyler M, Vallery, Richard S, Gidley, David W
Format: Journal Article
Language:English
Published: United States American Chemical Society 10-04-2018
Subjects:
ENGINEERING
free volume
MATERIALS SCIENCE
NANOSCIENCE AND NANOTECHNOLOGY
thiol-ene networks
viscoelastic damping
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Summary:Model thiol-click glassy networks with low shrinkage and sharp glass transition temperatures are studied down to cryogenic temperatures to relate viscoelastic damping to changes in microscopic hole volume. Networks synthesized by polymerization of divinyl sulfone with pentaerythritol tetrakis­(3-mercapto­propionate) (PETMP), trimethylol­propane tris­(3-mercapto­propionate) (TMPTMP), and pentaerythritol tetrakis­(2-mercaptoacetate) (PETT) were studied to ∼50 K using positron annihilation and thermal analysis methods. Across the glass transition temperature, overall volume expansivity is dominated by expansion of microscopic holes. Beneath T g, holes contract upon cooling and then become static with negligible expansivity at temperatures well above 0 K. A trade-off between complete rigidity of static free volume and viscoelastic damping ability below T g is discussed. All samples show moderate damping (tan δ > 0.05), and one sample exhibits a prominent β-transition in its viscoelastic loss spectra. These results indicate the potential for tuning the molecular design of low-temperature glassy networks to optimally incorporate damping with low shrinkage.
Bibliography:NA0003400
USDOE National Nuclear Security Administration (NNSA)
ISSN:0024-9297
1520-5835
DOI:10.1021/acs.macromol.8b00037