TY - JOUR
T1 - Local Viscosity of Interfacial Layers in Polymer Nanocomposites Measured by Magnetic Heating
AU - Wu, Di
AU - Weiblen, Donovan G.
AU - Ozisik, Rahmi
AU - Akcora, Pinar
N1 - Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/12/11
Y1 - 2020/12/11
N2 - The strength of interfacial attractions between polymer chains and nanoparticles is known to control the mobility of chains and viscoelastic properties in polymer nanocomposites. We chose the interfacial layers around magnetic nanoparticles to consist of two different miscible polymers and measured the energy absorption rates as particles dissipate energy while they rotate under a high-frequency alternating magnetic field. Local viscosities were calculated from the measured rotational relaxation times using the classical absorption model. The changes in local viscosities were attributed to the rigidity of adsorbed polymers and chemical heterogeneities of their interfacial layers. The highest viscosity was measured with the flexible, shorter adsorbed poly(methyl methacrylate) chains. The weak interphases between poly(methyl acrylate) and highly rigid polymers such as poly(2-vinyl pyridine), and poly(bisphenol A carbonate) allowed particles to rotate easily in a diffusive mode, yielding the lowest viscosity that matched to the viscosity prediction of an unentangled matrix polymer. Chemical and dynamic heterogeneity of interfacial layers around nanoparticles highly depend on the rigidity of chains. Measuring the local viscosity of interfacial polymer layers is essential for interfacial layer-controlled mechanisms of stress transfer, reinforcement, and thermal conductivity in polymer nanocomposites.
AB - The strength of interfacial attractions between polymer chains and nanoparticles is known to control the mobility of chains and viscoelastic properties in polymer nanocomposites. We chose the interfacial layers around magnetic nanoparticles to consist of two different miscible polymers and measured the energy absorption rates as particles dissipate energy while they rotate under a high-frequency alternating magnetic field. Local viscosities were calculated from the measured rotational relaxation times using the classical absorption model. The changes in local viscosities were attributed to the rigidity of adsorbed polymers and chemical heterogeneities of their interfacial layers. The highest viscosity was measured with the flexible, shorter adsorbed poly(methyl methacrylate) chains. The weak interphases between poly(methyl acrylate) and highly rigid polymers such as poly(2-vinyl pyridine), and poly(bisphenol A carbonate) allowed particles to rotate easily in a diffusive mode, yielding the lowest viscosity that matched to the viscosity prediction of an unentangled matrix polymer. Chemical and dynamic heterogeneity of interfacial layers around nanoparticles highly depend on the rigidity of chains. Measuring the local viscosity of interfacial polymer layers is essential for interfacial layer-controlled mechanisms of stress transfer, reinforcement, and thermal conductivity in polymer nanocomposites.
KW - chemical heterogeneity
KW - interfacial layer
KW - magnetic heating
KW - polymer nanocomposite
KW - viscosity
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U2 - 10.1021/acsapm.0c00889
DO - 10.1021/acsapm.0c00889
M3 - Article
AN - SCOPUS:85099265257
VL - 2
SP - 5542
EP - 5549
JO - ACS Applied Polymer Materials
JF - ACS Applied Polymer Materials
IS - 12
ER -