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Merrill JH, Li R, Roth CB. End-Tethered Chains Increase the Local Glass Transition Temperature of Matrix Chains by 45 K Next to Solid Substrates Independent of Chain Length. ACS Macro Lett 2023; 12:1-7. [PMID: 36516977 DOI: 10.1021/acsmacrolett.2c00582] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The local glass transition temperature Tg of pyrene-labeled polystyrene (PS) chains intermixed with end-tethered PS chains grafted to a neutral silica substrate was measured by fluorescence spectroscopy. To isolate the impact of the grafted chains, the films were capped with bulk neat PS layers eliminating competing effects of the free surface. Results demonstrate that end-grafted chains strongly increase the local Tg of matrix chains by ≈45 K relative to bulk Tg, independent of grafted chain molecular weight from Mn = 8.6 to 212 kg/mol and chemical end-group, over a wide range of grafting densities σ = 0.003 to 0.33 chains/nm2 spanning the mushroom-to-brush transition regime. The tens-of-degree increase in local Tg resulting from immobilization of the chain ends by covalent bonding in this athermal system suggests a mechanism that substantially increases the local activation energy required for cooperative rearrangements.
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Affiliation(s)
- James H Merrill
- Department of Physics, Emory University, Atlanta, Georgia30322, United States
| | - Ruoyu Li
- Department of Physics, Emory University, Atlanta, Georgia30322, United States
| | - Connie B Roth
- Department of Physics, Emory University, Atlanta, Georgia30322, United States
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Yan J, Xu J, Weng LT, Wang F, Wang X, Yuan H, Wang T, Tsui OKC. Glass Transition of the Surface Monolayer of Polystyrene Films with Different Film Thicknesses and Supporting Surfaces. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c02013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jinsong Yan
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
| | - Jianquan Xu
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou310018, China
| | - Lu-Tao Weng
- Materials Characterization and Preparation Facility (GZ), Advanced Materials Thrust, The Hong Kong University of Science and Technology (Guangzhou), Nansha, Guangzhou511400, Guangdong, China
- Department of Chemical and Biological Engineering, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
| | - Fengliang Wang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou310018, China
| | - Xinping Wang
- Department of Chemistry, Key Laboratory of Surface & Interface Science of Polymer Materials of Zhejiang Province, Zhejiang Sci-Tech University, Hangzhou310018, China
| | - Hailin Yuan
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
| | - Tong Wang
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
- Department of Materials Science & Engineering, Northwestern University, Evanston, Illinois60208-3120, United States
| | - Ophelia K. C. Tsui
- Department of Physics, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
- William Mong Institute of Nano Science and Technology, Hong Kong University of Science and Technology, Kowloon, 999077Hong Kong, China
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Wang T, Hu S, Zhang S, Peera A, Reffner J, Torkelson JM. Eliminating the Tg-Confinement Effect in Polystyrene Films: Extraordinary Impact of a 2 mol % 2-Ethylhexyl Acrylate Comonomer. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tong Wang
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Sumeng Hu
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois60208, United States
| | - Sipei Zhang
- The Dow Chemical Company, 400 Arcola Road, Collegeville, Pennsylvania19426, United States
| | - Asghar Peera
- The Dow Chemical Company, 400 Arcola Road, Collegeville, Pennsylvania19426, United States
| | - John Reffner
- The Dow Chemical Company, 400 Arcola Road, Collegeville, Pennsylvania19426, United States
| | - John M. Torkelson
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois60208, United States
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois60208, United States
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Petek ES, Katsumata R. Thickness Dependence of Contact Angles in Multilayered Ultrathin Polymer Films. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Evon S. Petek
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, 120 Governors Dr, Amherst, Massachusetts 01003, United States
| | - Reika Katsumata
- Department of Polymer Science and Engineering, University of Massachusetts Amherst, 120 Governors Dr, Amherst, Massachusetts 01003, United States
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Han Y, Roth CB. Temperature dependent perylene fluorescence as a probe of local polymer glass transition dynamics. SOFT MATTER 2022; 18:6094-6104. [PMID: 35929948 DOI: 10.1039/d2sm00552b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We demonstrate how the temperature dependence of perylene's fluorescence emission spectrum doped in bulk polymer matrices is sensitive to the local glass transition dynamics of the surrounding polymer segments. Focusing on the first fluorescence peak, we show that the intensity ratio IRatio(T) = IPeak(T)/ISRR between the first peak and a self referencing region (SRR) has a temperature dependence resulting from the temperature-dependent nonradiative decay pathway of the excited perylene dye that is influenced by its intermolecular collisions with the surrounding polymers segments. For different polymer matrices, poly(methyl methacrylate) (PMMA), polystyrene (PS), poly(2-vinyl pyridine) (P2VP), and polycarbonate (PC), we demonstrate that IRatio(T) exhibits a transition from a non-Arrhenius behavior above the glass transition temperature Tg of the polymer to an Arrhenius temperature dependence with constant activation energy E below the Tg of the polymer matrix, indicating perylene's sensitivity to cooperative α-relaxation dynamics of the polymer matrix. This transition in temperature dependence allows us to identify a perylene defined local Tperyleneg of the surrounding polymer matrix that agrees well with the known Tg values of the polymers. We define a fluorescence intensity shift factor in analogy with the Williams-Landel-Ferry (WLF) equation and use literature WLF parameters for the polymer matrix to quantify the calibration factor cf needed to convert the fluorescence intensity ratio to the effective time scale ratio described by the conventional WLF shift factor. This work opens up a new characterization method that could be used to map the local dynamical response of the glass transition in nanoscale polymer materials using appropriate covalent attachment of perylene to polymer chains.
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Affiliation(s)
- Yixuan Han
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA.
| | - Connie B Roth
- Department of Physics, Emory University, Atlanta, Georgia 30322, USA.
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