Shear Rheology of Unentangled and Marginally Entangled Ring Polymer Melts from Large-Scale Nonequilibrium Molecular Dynamics Simulations.
Identifieur interne : 000479 ( Main/Exploration ); précédent : 000478; suivant : 000480Shear Rheology of Unentangled and Marginally Entangled Ring Polymer Melts from Large-Scale Nonequilibrium Molecular Dynamics Simulations.
Auteurs : Alexandros J. Tsamopoulos [Grèce] ; Anna F. Katsarou [Grèce] ; Dimitrios G. Tsalikis [Grèce] ; Vlasis G. Mavrantzas [Grèce, Suisse]Source :
- Polymers [ 2073-4360 ] ; 2019.
Abstract
We present results for the steady state shear rheology of non-concatenated, unentangled and marginally entangled ring poly(ethylene oxide) (PEO) melts from detailed, atomistic nonequilibrium molecular dynamics (NEMD) simulations, and compare them to the behavior of the corresponding linear melts. The applied flow field spans a wide range of shear rates, from the linear (Newtonian) to the highly non-linear (described by a power law) regime. For all melts studied, rings are found to exhibit shear thinning but to a lesser degree compared to linear counterparts, mostly due to their reduced deformability and stronger resistance to alignment in the direction of flow. These features are attributed to the more compact structure of ring molecules compared to linear chains; the latter are capable of adopting wider and more open conformations even under shear due to the freedom provided by the free ends. Similar to linear melts, rings also exhibit a first and a second normal stress coefficient; the latter is negative. The ratio of the magnitude of the two coefficients remains practically constant with shear rate and is systematically higher than the corresponding one for linear melts. Emphasis was also given to the statistics of terminal (re-orientational) relaxation times which we computed by analyzing all chains in the simulated systems one by one; it was demonstrated that long time dynamics are strongly heterogeneous both for rings and (especially) linears. Repeating the analysis under flow conditions, and as expected, we found that the applied flow field significantly suppresses dynamic heterogeneity, especially for high shear rates well beyond the Newtonian plateau. Finally, a detailed geometrical analysis revealed that the average population of ring-ring threading events in the longest melt studied here (the PEO-5k ring) remains practically unaffected by the imposed flow rate even at strong shear rates, except for multi-threadings which disappear. To further analyze this peculiar and rather unexpected effect, we computed the corresponding survival times and penetration lengths, and found that the overwhelming majority of threadings under shear are extremely weak constraints, as they are characterized by very small penetration lengths, thus also by short survival times. They are expected therefore to play only a minor (if any) role on chain dynamics.
DOI: 10.3390/polym11071194
PubMed: 31319474
PubMed Central: PMC6680584
Affiliations:
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Tsamopoulos</name><affiliation wicri:level="1"><nlm:affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece.</nlm:affiliation><country xml:lang="fr">Grèce</country><wicri:regionArea>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras</wicri:regionArea><wicri:noRegion>GR 26504 Patras</wicri:noRegion></affiliation></author><author><name sortKey="Katsarou, Anna F" sort="Katsarou, Anna F" uniqKey="Katsarou A" first="Anna F" last="Katsarou">Anna F. Katsarou</name><affiliation wicri:level="1"><nlm:affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece.</nlm:affiliation><country xml:lang="fr">Grèce</country><wicri:regionArea>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras</wicri:regionArea><wicri:noRegion>GR 26504 Patras</wicri:noRegion></affiliation></author><author><name sortKey="Tsalikis, Dimitrios G" sort="Tsalikis, Dimitrios G" uniqKey="Tsalikis D" first="Dimitrios G" last="Tsalikis">Dimitrios G. Tsalikis</name><affiliation wicri:level="1"><nlm:affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece. vlasis@chemeng.upatras.gr.</nlm:affiliation><country xml:lang="fr">Grèce</country><wicri:regionArea>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras</wicri:regionArea><wicri:noRegion>GR 26504 Patras</wicri:noRegion></affiliation></author><author><name sortKey="Mavrantzas, Vlasis G" sort="Mavrantzas, Vlasis G" uniqKey="Mavrantzas V" first="Vlasis G" last="Mavrantzas">Vlasis G. Mavrantzas</name><affiliation wicri:level="1"><nlm:affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece. vlasiosm@mat.ethz.ch.</nlm:affiliation><country xml:lang="fr">Grèce</country><wicri:regionArea>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras</wicri:regionArea><wicri:noRegion>GR 26504 Patras</wicri:noRegion></affiliation><affiliation wicri:level="1"><nlm:affiliation>Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland. vlasiosm@mat.ethz.ch.</nlm:affiliation><country xml:lang="fr">Suisse</country><wicri:regionArea>Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich</wicri:regionArea><wicri:noRegion>CH-8092 Zürich</wicri:noRegion></affiliation></author></analytic><series><title level="j">Polymers</title><idno type="eISSN">2073-4360</idno><imprint><date when="2019" type="published">2019</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">We present results for the steady state shear rheology of non-concatenated, unentangled and marginally entangled ring poly(ethylene oxide) (PEO) melts from detailed, atomistic nonequilibrium molecular dynamics (NEMD) simulations, and compare them to the behavior of the corresponding linear melts. The applied flow field spans a wide range of shear rates, from the linear (Newtonian) to the highly non-linear (described by a power law) regime. For all melts studied, rings are found to exhibit shear thinning but to a lesser degree compared to linear counterparts, mostly due to their reduced deformability and stronger resistance to alignment in the direction of flow. These features are attributed to the more compact structure of ring molecules compared to linear chains; the latter are capable of adopting wider and more open conformations even under shear due to the freedom provided by the free ends. Similar to linear melts, rings also exhibit a first and a second normal stress coefficient; the latter is negative. The ratio of the magnitude of the two coefficients remains practically constant with shear rate and is systematically higher than the corresponding one for linear melts. Emphasis was also given to the statistics of terminal (re-orientational) relaxation times which we computed by analyzing all chains in the simulated systems one by one; it was demonstrated that long time dynamics are strongly heterogeneous both for rings and (especially) linears. Repeating the analysis under flow conditions, and as expected, we found that the applied flow field significantly suppresses dynamic heterogeneity, especially for high shear rates well beyond the Newtonian plateau. Finally, a detailed geometrical analysis revealed that the average population of ring-ring threading events in the longest melt studied here (the PEO-5k ring) remains practically unaffected by the imposed flow rate even at strong shear rates, except for multi-threadings which disappear. To further analyze this peculiar and rather unexpected effect, we computed the corresponding survival times and penetration lengths, and found that the overwhelming majority of threadings under shear are extremely weak constraints, as they are characterized by very small penetration lengths, thus also by short survival times. They are expected therefore to play only a minor (if any) role on chain dynamics.</div></front></TEI><pubmed><MedlineCitation Status="PubMed-not-MEDLINE" Owner="NLM"><PMID Version="1">31319474</PMID><DateRevised><Year>2020</Year><Month>10</Month><Day>01</Day></DateRevised><Article PubModel="Electronic"><Journal><ISSN IssnType="Electronic">2073-4360</ISSN><JournalIssue CitedMedium="Internet"><Volume>11</Volume><Issue>7</Issue><PubDate><Year>2019</Year><Month>Jul</Month><Day>17</Day></PubDate></JournalIssue><Title>Polymers</Title><ISOAbbreviation>Polymers (Basel)</ISOAbbreviation></Journal><ArticleTitle>Shear Rheology of Unentangled and Marginally Entangled Ring Polymer Melts from Large-Scale Nonequilibrium Molecular Dynamics Simulations.</ArticleTitle><ELocationID EIdType="pii" ValidYN="Y">E1194</ELocationID><ELocationID EIdType="doi" ValidYN="Y">10.3390/polym11071194</ELocationID><Abstract><AbstractText>We present results for the steady state shear rheology of non-concatenated, unentangled and marginally entangled ring poly(ethylene oxide) (PEO) melts from detailed, atomistic nonequilibrium molecular dynamics (NEMD) simulations, and compare them to the behavior of the corresponding linear melts. The applied flow field spans a wide range of shear rates, from the linear (Newtonian) to the highly non-linear (described by a power law) regime. For all melts studied, rings are found to exhibit shear thinning but to a lesser degree compared to linear counterparts, mostly due to their reduced deformability and stronger resistance to alignment in the direction of flow. These features are attributed to the more compact structure of ring molecules compared to linear chains; the latter are capable of adopting wider and more open conformations even under shear due to the freedom provided by the free ends. Similar to linear melts, rings also exhibit a first and a second normal stress coefficient; the latter is negative. The ratio of the magnitude of the two coefficients remains practically constant with shear rate and is systematically higher than the corresponding one for linear melts. Emphasis was also given to the statistics of terminal (re-orientational) relaxation times which we computed by analyzing all chains in the simulated systems one by one; it was demonstrated that long time dynamics are strongly heterogeneous both for rings and (especially) linears. Repeating the analysis under flow conditions, and as expected, we found that the applied flow field significantly suppresses dynamic heterogeneity, especially for high shear rates well beyond the Newtonian plateau. Finally, a detailed geometrical analysis revealed that the average population of ring-ring threading events in the longest melt studied here (the PEO-5k ring) remains practically unaffected by the imposed flow rate even at strong shear rates, except for multi-threadings which disappear. To further analyze this peculiar and rather unexpected effect, we computed the corresponding survival times and penetration lengths, and found that the overwhelming majority of threadings under shear are extremely weak constraints, as they are characterized by very small penetration lengths, thus also by short survival times. They are expected therefore to play only a minor (if any) role on chain dynamics.</AbstractText></Abstract><AuthorList CompleteYN="Y"><Author ValidYN="Y"><LastName>Tsamopoulos</LastName><ForeName>Alexandros J</ForeName><Initials>AJ</Initials><AffiliationInfo><Affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Katsarou</LastName><ForeName>Anna F</ForeName><Initials>AF</Initials><AffiliationInfo><Affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Tsalikis</LastName><ForeName>Dimitrios G</ForeName><Initials>DG</Initials><Identifier Source="ORCID">0000-0003-3599-0676</Identifier><AffiliationInfo><Affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece. vlasis@chemeng.upatras.gr.</Affiliation></AffiliationInfo></Author><Author ValidYN="Y"><LastName>Mavrantzas</LastName><ForeName>Vlasis G</ForeName><Initials>VG</Initials><AffiliationInfo><Affiliation>Department of Chemical Engineering, University of Patras and FORTH-ICE/HT, GR 26504 Patras, Greece. vlasiosm@mat.ethz.ch.</Affiliation></AffiliationInfo><AffiliationInfo><Affiliation>Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland. vlasiosm@mat.ethz.ch.</Affiliation></AffiliationInfo></Author></AuthorList><Language>eng</Language><GrantList CompleteYN="Y"><Grant><GrantID>"Multiscale Simulations of Complex Polymer Systems" (MuSiComPS)</GrantID><Agency>Limmat Foundation, Zurich, Switzerland</Agency><Country></Country></Grant></GrantList><PublicationTypeList><PublicationType UI="D016428">Journal Article</PublicationType></PublicationTypeList><ArticleDate DateType="Electronic"><Year>2019</Year><Month>07</Month><Day>17</Day></ArticleDate></Article><MedlineJournalInfo><Country>Switzerland</Country><MedlineTA>Polymers (Basel)</MedlineTA><NlmUniqueID>101545357</NlmUniqueID><ISSNLinking>2073-4360</ISSNLinking></MedlineJournalInfo><KeywordList Owner="NOTNLM"><Keyword MajorTopicYN="N">nonequilibrium simulation</Keyword><Keyword MajorTopicYN="N">polymer rheology</Keyword><Keyword MajorTopicYN="N">ring polymers</Keyword></KeywordList></MedlineCitation><PubmedData><History><PubMedPubDate PubStatus="received"><Year>2019</Year><Month>05</Month><Day>13</Day></PubMedPubDate><PubMedPubDate PubStatus="revised"><Year>2019</Year><Month>06</Month><Day>29</Day></PubMedPubDate><PubMedPubDate PubStatus="accepted"><Year>2019</Year><Month>07</Month><Day>05</Day></PubMedPubDate><PubMedPubDate PubStatus="entrez"><Year>2019</Year><Month>7</Month><Day>20</Day><Hour>6</Hour><Minute>0</Minute></PubMedPubDate><PubMedPubDate 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IdType="pubmed">9895674</ArticleId></ArticleIdList></Reference></ReferenceList></PubmedData></pubmed><affiliations><list><country><li>Grèce</li><li>Suisse</li></country></list><tree><country name="Grèce"><noRegion><name sortKey="Tsamopoulos, Alexandros J" sort="Tsamopoulos, Alexandros J" uniqKey="Tsamopoulos A" first="Alexandros J" last="Tsamopoulos">Alexandros J. Tsamopoulos</name></noRegion><name sortKey="Katsarou, Anna F" sort="Katsarou, Anna F" uniqKey="Katsarou A" first="Anna F" last="Katsarou">Anna F. Katsarou</name><name sortKey="Mavrantzas, Vlasis G" sort="Mavrantzas, Vlasis G" uniqKey="Mavrantzas V" first="Vlasis G" last="Mavrantzas">Vlasis G. Mavrantzas</name><name sortKey="Tsalikis, Dimitrios G" sort="Tsalikis, Dimitrios G" uniqKey="Tsalikis D" first="Dimitrios G" last="Tsalikis">Dimitrios G. Tsalikis</name></country><country name="Suisse"><noRegion><name sortKey="Mavrantzas, Vlasis G" sort="Mavrantzas, Vlasis G" uniqKey="Mavrantzas V" first="Vlasis G" last="Mavrantzas">Vlasis G. Mavrantzas</name></noRegion></country></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
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