Abstract
Broadband dielectric spectroscopy, differential scanning calorimetry, and rheology were employed to study the impact of hydrogen (H)-bonding end-groups on segmental and chain dynamics of telechelic polypropylene glycol (PPG) and poly(dimethylsiloxane) (PDMS). Polymer chains with three types of H-bonding end-groups possessing different interaction strengths and a non-H-bonding end-group as reference were compared. The glass transition temperature (Tg) of H-bonding PPG systems with low molecular weight increases compared to the reference, and the Tg difference varies with chain-end interaction strength. In contrast, their shear viscosities (for Tg-scaled temperature, i.e., when the shift in Tg is accounted for) are similar to that one of the reference. This is in strong contrast to the behavior of telechelic PDMS with the same set of end-groups, where the Tg increase of all H-bonding systems is independent of H-bond strengths, while shear viscosity increases significantly only for the strongest H-bonding end-groups. These observations are explained by the difference in lifetime of the end-group associations relative to segmental and chain relaxation times.
Original language | English |
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Pages (from-to) | 8561-8573 |
Number of pages | 13 |
Journal | Macromolecules |
Volume | 51 |
Issue number | 21 |
DOIs | |
State | Published - Nov 13 2018 |
Funding
This work was supported by the NSF Polymer program under Grant DMR-1408811. M.T. is grateful to the Alexander von Humboldt Foundation for granting him a Feodor-Lynen fellowship. P.C. and T.S. acknowledge partial financial support for polymer synthesis by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science & Engineering Division.
Funders | Funder number |
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Materials Science & Engineering Division | |
National Science Foundation | DMR-1408811 |
U.S. Department of Energy | |
Alexander von Humboldt-Stiftung | |
Office of Science | |
Basic Energy Sciences |