2022
DOI: 10.1103/physrevx.12.021047
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Cooperative Intramolecular Dynamics Control the Chain-Length-Dependent Glass Transition in Polymers

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Cited by 14 publications
(22 citation statements)
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“…[64][65][66][67] Recent theoretical efforts by Ghosh and Schweizer modeling associating polymers treated the "sticky" groups as causing persistent caging units, finding that the energy barrier for hopping could double for only 10% sticky groups, leading to slower segmental dynamics by ∼9 orders of magnitude, equivalent to a T g increase of ∼30 K. 65 How exactly chain connectivity alters the energy barrier for co-operative rearrangements is still an area of active research. 64,65,[68][69][70] Given all these considerations, we conclude that chain connectivity to the substrate interface by covalent bonding is key to causing the large increase in local T g , yet we note that the pyrene dye is only attached to the intermixed homopolymer chains, not to the tethered chains themselves. The large ≈45 K magnitude in local T g increase implies slower segmental dynamics by at least ∼10 orders of magnitude suggesting that grafting causes a substantial (at least factor of two) increase in the energy barrier associated with local cooperative rearrangements.…”
Section: Mnmentioning
confidence: 71%
“…[64][65][66][67] Recent theoretical efforts by Ghosh and Schweizer modeling associating polymers treated the "sticky" groups as causing persistent caging units, finding that the energy barrier for hopping could double for only 10% sticky groups, leading to slower segmental dynamics by ∼9 orders of magnitude, equivalent to a T g increase of ∼30 K. 65 How exactly chain connectivity alters the energy barrier for co-operative rearrangements is still an area of active research. 64,65,[68][69][70] Given all these considerations, we conclude that chain connectivity to the substrate interface by covalent bonding is key to causing the large increase in local T g , yet we note that the pyrene dye is only attached to the intermixed homopolymer chains, not to the tethered chains themselves. The large ≈45 K magnitude in local T g increase implies slower segmental dynamics by at least ∼10 orders of magnitude suggesting that grafting causes a substantial (at least factor of two) increase in the energy barrier associated with local cooperative rearrangements.…”
Section: Mnmentioning
confidence: 71%
“…For polymeric materials, the material properties depend strongly on molecular weight, especially for relatively short polymers (M o 10 000 g mol À1 ). 1,[98][99][100][101][102][103] Here, we consider only the high-molecular weight limit (M 4 100 000 g mol À1 ). In principle, the SL-TS2 parameters for polymers should be molecular-weight-dependent, in the same way as VFTH or WLF parameters are.…”
Section: Discussionmentioning
confidence: 99%
“…Rather, the magnitude of the T g increase caused by grafting is comparable to that observed in associating polymers such as ionomers, vitrimers, and telechelic polymers where chains become tethered to cluster centers. Recent theoretical efforts by Ghosh and Schweizer modeling associating polymers treated the “sticky” groups as causing persistent caging units and found that the energy barrier for hopping could double for only 10% sticky groups, leading to slower segmental dynamics by ∼9 orders of magnitude, equivalent to a T g increase of ∼30 K . How exactly chain connectivity alters the energy barrier for cooperative rearrangements is still an area of active research. ,, …”
mentioning
confidence: 97%