Nonmonotonic Glass Transition Temperature of Polymer Films Supported on Polymer Brushes

Hoyeon Lee; Vaidyanathan Sethuraman; Yeongsik Kim; Wooseop Lee; Du Yeol Ryu; Venkat Ganesan

doi:10.1021/acs.macromol.8b00290

Nonmonotonic Glass Transition Temperature of Polymer Films Supported on Polymer Brushes

Hoyeon Lee, Vaidyanathan Sethuraman, Yeongsik Kim, Wooseop Lee, Du Yeol Ryu, Venkat Ganesan

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

19 Scopus citations

Abstract

We modulated the grafting density (σ) and chain length of polystyrene (PS) brushes on substrates to probe their effect on the glass transition temperature (T_g) in overlaying PS thin films. The T_g of PS films was analyzed as a function of brush thickness (or σR_g ²), where R_g is the radius of gyration of PS brushes. Our results indicate that PS films below 90 nm exhibit a nonmonotonic dependence of T_g on grafting density with the maximum T_g occurring near the regime of wetting-dewetting transition of the overlaying melt. The maximum T_g was found to be higher than the value of bulk PS system. Computer simulation results suggest that such trends arise as a consequence of the environment of enhanced friction presented by the brush layer and the overlap between the polymer film and the grafted layer.

Original language	English
Pages (from-to)	4451-4461
Number of pages	11
Journal	Macromolecules
Volume	51
Issue number	12
DOIs	https://doi.org/10.1021/acs.macromol.8b00290
State	Published - Jun 26 2018
Externally published	Yes

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title = "Nonmonotonic Glass Transition Temperature of Polymer Films Supported on Polymer Brushes",

abstract = "We modulated the grafting density (σ) and chain length of polystyrene (PS) brushes on substrates to probe their effect on the glass transition temperature (Tg) in overlaying PS thin films. The Tg of PS films was analyzed as a function of brush thickness (or σRg 2), where Rg is the radius of gyration of PS brushes. Our results indicate that PS films below 90 nm exhibit a nonmonotonic dependence of Tg on grafting density with the maximum Tg occurring near the regime of wetting-dewetting transition of the overlaying melt. The maximum Tg was found to be higher than the value of bulk PS system. Computer simulation results suggest that such trends arise as a consequence of the environment of enhanced friction presented by the brush layer and the overlap between the polymer film and the grafted layer.",

author = "Hoyeon Lee and Vaidyanathan Sethuraman and Yeongsik Kim and Wooseop Lee and Ryu, {Du Yeol} and Venkat Ganesan",

note = "Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",

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doi = "10.1021/acs.macromol.8b00290",

language = "English",

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T1 - Nonmonotonic Glass Transition Temperature of Polymer Films Supported on Polymer Brushes

AU - Lee, Hoyeon

AU - Sethuraman, Vaidyanathan

AU - Kim, Yeongsik

AU - Lee, Wooseop

AU - Ryu, Du Yeol

AU - Ganesan, Venkat

PY - 2018/6/26

Y1 - 2018/6/26

N2 - We modulated the grafting density (σ) and chain length of polystyrene (PS) brushes on substrates to probe their effect on the glass transition temperature (Tg) in overlaying PS thin films. The Tg of PS films was analyzed as a function of brush thickness (or σRg 2), where Rg is the radius of gyration of PS brushes. Our results indicate that PS films below 90 nm exhibit a nonmonotonic dependence of Tg on grafting density with the maximum Tg occurring near the regime of wetting-dewetting transition of the overlaying melt. The maximum Tg was found to be higher than the value of bulk PS system. Computer simulation results suggest that such trends arise as a consequence of the environment of enhanced friction presented by the brush layer and the overlap between the polymer film and the grafted layer.

AB - We modulated the grafting density (σ) and chain length of polystyrene (PS) brushes on substrates to probe their effect on the glass transition temperature (Tg) in overlaying PS thin films. The Tg of PS films was analyzed as a function of brush thickness (or σRg 2), where Rg is the radius of gyration of PS brushes. Our results indicate that PS films below 90 nm exhibit a nonmonotonic dependence of Tg on grafting density with the maximum Tg occurring near the regime of wetting-dewetting transition of the overlaying melt. The maximum Tg was found to be higher than the value of bulk PS system. Computer simulation results suggest that such trends arise as a consequence of the environment of enhanced friction presented by the brush layer and the overlap between the polymer film and the grafted layer.

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Nonmonotonic Glass Transition Temperature of Polymer Films Supported on Polymer Brushes

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