Conflicting Confinement Effects on the Tg, Diffusivity, and Effective Viscosity of Polymer Films: A Case Study with Poly(isobutyl methacrylate) on Silica and Possible Resolution

Kun Geng; Reika Katsumata; Xuanji Yu; Heonjoo Ha; Austin R. Dulaney; Christopher J. Ellison; Ophelia K.C. Tsui

doi:10.1021/acs.macromol.6b01354

Conflicting Confinement Effects on the T_g, Diffusivity, and Effective Viscosity of Polymer Films: A Case Study with Poly(isobutyl methacrylate) on Silica and Possible Resolution

Kun Geng, Reika Katsumata, Xuanji Yu, Heonjoo Ha, Austin R. Dulaney, Christopher J. Ellison, Ophelia K.C. Tsui

Chemical Engineering and Materials Science

Research output: Contribution to journal › Article › peer-review

29 Scopus citations

Abstract

The glass transition temperature (T_g), in-plane diffusivity (D), and effective viscosity (η_eff) were measured for the same thin film system of poly(isobutyl methacrylate) supported by silica (PiBMA/SiOx). We found that both the T_g and D were independent of the film thickness (h₀), but η_eff decreased with decreasing h₀. We envisage the different h₀ dependencies to be caused by T_g, D, and η_eff being different functions of the local T_g’s (T_g,i) or viscosities (η_i), which vary with the film depth. By assuming a three-layer model and that T_g(h₀) = ⟨T_g,i⟩, D(h₀) ∼ k_BT/⟨η_i⟩, and η_eff(h₀) = h₀³/3M_tot(η_i), where ⟨...⟩ denotes spatial averaging and M_tot is the mobility of the films, we were able to account for the experimental data. By extending these ideas to the analogous data of polystyrene supported by silica (PS/SiOx), a resolution was found for the long-standing inconsistency regarding the effects of confinement on the dynamics of polymer films.

Original language	English (US)
Pages (from-to)	609-617
Number of pages	9
Journal	Macromolecules
Volume	50
Issue number	2
DOIs	https://doi.org/10.1021/acs.macromol.6b01354
State	Published - Jan 24 2017

Bibliographical note

Funding Information:
This work is funded by the National Science Foundation through the grant award DMR-1310536 and CAREER award DMR-1053293. R.K. appreciates the Takenaka Scholarship and Graduate Dean’s Prestigious Fellowship Supplement for financial support.

Publisher Copyright:
© 2017 American Chemical Society.

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10.1021/acs.macromol.6b01354

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@article{4f956439123a4fd2b7dfc8a865759728,

title = "Conflicting Confinement Effects on the Tg, Diffusivity, and Effective Viscosity of Polymer Films: A Case Study with Poly(isobutyl methacrylate) on Silica and Possible Resolution",

abstract = "The glass transition temperature (Tg), in-plane diffusivity (D), and effective viscosity (ηeff) were measured for the same thin film system of poly(isobutyl methacrylate) supported by silica (PiBMA/SiOx). We found that both the Tg and D were independent of the film thickness (h0), but ηeff decreased with decreasing h0. We envisage the different h0 dependencies to be caused by Tg, D, and ηeff being different functions of the local Tg{\textquoteright}s (Tg,i) or viscosities (ηi), which vary with the film depth. By assuming a three-layer model and that Tg(h0) = ⟨Tg,i⟩, D(h0) ∼ kBT/⟨ηi⟩, and ηeff(h0) = h03/3Mtot(ηi), where ⟨...⟩ denotes spatial averaging and Mtot is the mobility of the films, we were able to account for the experimental data. By extending these ideas to the analogous data of polystyrene supported by silica (PS/SiOx), a resolution was found for the long-standing inconsistency regarding the effects of confinement on the dynamics of polymer films.",

author = "Kun Geng and Reika Katsumata and Xuanji Yu and Heonjoo Ha and Dulaney, {Austin R.} and Ellison, {Christopher J.} and Tsui, {Ophelia K.C.}",

note = "Funding Information: This work is funded by the National Science Foundation through the grant award DMR-1310536 and CAREER award DMR-1053293. R.K. appreciates the Takenaka Scholarship and Graduate Dean{\textquoteright}s Prestigious Fellowship Supplement for financial support. Publisher Copyright: {\textcopyright} 2017 American Chemical Society.",

year = "2017",

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doi = "10.1021/acs.macromol.6b01354",

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T1 - Conflicting Confinement Effects on the Tg, Diffusivity, and Effective Viscosity of Polymer Films

T2 - A Case Study with Poly(isobutyl methacrylate) on Silica and Possible Resolution

AU - Geng, Kun

AU - Katsumata, Reika

AU - Yu, Xuanji

AU - Ha, Heonjoo

AU - Dulaney, Austin R.

AU - Ellison, Christopher J.

AU - Tsui, Ophelia K.C.

N1 - Funding Information: This work is funded by the National Science Foundation through the grant award DMR-1310536 and CAREER award DMR-1053293. R.K. appreciates the Takenaka Scholarship and Graduate Dean’s Prestigious Fellowship Supplement for financial support. Publisher Copyright: © 2017 American Chemical Society.

PY - 2017/1/24

Y1 - 2017/1/24

N2 - The glass transition temperature (Tg), in-plane diffusivity (D), and effective viscosity (ηeff) were measured for the same thin film system of poly(isobutyl methacrylate) supported by silica (PiBMA/SiOx). We found that both the Tg and D were independent of the film thickness (h0), but ηeff decreased with decreasing h0. We envisage the different h0 dependencies to be caused by Tg, D, and ηeff being different functions of the local Tg’s (Tg,i) or viscosities (ηi), which vary with the film depth. By assuming a three-layer model and that Tg(h0) = ⟨Tg,i⟩, D(h0) ∼ kBT/⟨ηi⟩, and ηeff(h0) = h03/3Mtot(ηi), where ⟨...⟩ denotes spatial averaging and Mtot is the mobility of the films, we were able to account for the experimental data. By extending these ideas to the analogous data of polystyrene supported by silica (PS/SiOx), a resolution was found for the long-standing inconsistency regarding the effects of confinement on the dynamics of polymer films.

AB - The glass transition temperature (Tg), in-plane diffusivity (D), and effective viscosity (ηeff) were measured for the same thin film system of poly(isobutyl methacrylate) supported by silica (PiBMA/SiOx). We found that both the Tg and D were independent of the film thickness (h0), but ηeff decreased with decreasing h0. We envisage the different h0 dependencies to be caused by Tg, D, and ηeff being different functions of the local Tg’s (Tg,i) or viscosities (ηi), which vary with the film depth. By assuming a three-layer model and that Tg(h0) = ⟨Tg,i⟩, D(h0) ∼ kBT/⟨ηi⟩, and ηeff(h0) = h03/3Mtot(ηi), where ⟨...⟩ denotes spatial averaging and Mtot is the mobility of the films, we were able to account for the experimental data. By extending these ideas to the analogous data of polystyrene supported by silica (PS/SiOx), a resolution was found for the long-standing inconsistency regarding the effects of confinement on the dynamics of polymer films.

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