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Interplay between end-association and entanglement in hydrogen-bonded telechelic polymers: A sticky situation

Takagi, Akira and Kornfield, Julia A. (2014) Interplay between end-association and entanglement in hydrogen-bonded telechelic polymers: A sticky situation. Abstracts of Papers of the American Chemical Society, 248 . 523-PMSE. ISSN 0065-7727. https://resolver.caltech.edu/CaltechAUTHORS:20150323-084316686

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Abstract

A relatively new class of supramols.-highly entangled, end-functional polymers-are accessible through efficient ROMP+CTA (ring-opening metathesis polymn. with chain transfer agents) synthesis. At high concn. or in the melt, assocn. among the end-groups of entangled chains (>25 M_e) frustrates their reptation relaxation. This broadens the time range in which the materials behave in an elastomeric manner. The activation energy of end-assocn. can be tuned using polyvalent hydrogen bonding. Here, we compare polybutadienes that have either two or four carboxylate groups at each end. The activation energy for end-assocn. controls the time scale and temp. dependence of the terminal relaxation. For example, having two carboxylates at each end slows the terminal relaxation of a 50kg/mol PB by three orders of magnitude at ambient temp.-and by more than four orders of magnitude at 5°C. Thus, the terminal relaxation shifts more strongly with temp. than the chain segmental motion, giving an enlightening failure of time-temp. superposition. Two relaxation modes are evident: a "fast mode" assigned to the rearrangement of entangled chains constrained by end assocn. and a "slow mode" assigned to the end group exchange. Adding short polybutadiene as a dilutent helps to expose the underlying dynamics and leads to interesting adhesive materials.


Item Type:Article
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http://www.acs.org/content/acs/en/meetings/fall-2014.htmlOrganizationConference Website
ORCID:
AuthorORCID
Kornfield, Julia A.0000-0001-6746-8634
Additional Information:© 2014 American Chemical Society.
Record Number:CaltechAUTHORS:20150323-084316686
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150323-084316686
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:55956
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:23 Mar 2015 18:08
Last Modified:03 Oct 2019 08:10

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