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Wang T, Young WO, Suazo MJ, Peera A, Carter MCD, Yeung K, Li L, Torkelson JM. Random Copolymers Based on 2-Ethylhexyl Acrylate Exhibit Unusual Glass Transition Breadth and Facile Autonomous Self-Healing over a Broad Composition Range. Macromol Rapid Commun 2024:e2400198. [PMID: 39150329 DOI: 10.1002/marc.202400198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/24/2024] [Indexed: 08/17/2024]
Abstract
Statistical copolymers are commercially important because their properties can be tuned by comonomer selection and composition. Rubbery-state styrene (S)/n-butyl acrylate (nBA) copolymers have previously been reported to exhibit facile, autonomous self-healing over a narrow composition band (47/53 to 53/47 mol%). The need for a narrow composition band is explained by alternating comonomer sequences that accommodate interchain secondary bonding. It is hypothesized that copolymers that achieve interchain secondary bonding without alternating sequences can exhibit facile self-healing over a broad composition range. 2-ethylhexyl acrylate (EHA) is identified as yielding sequence-independent secondary bonding interactions. For these interactions it is tested experimentally by glass transition breadth in rubbery-state S/EHA copolymers, with S/n-hexyl acrylate (nHA) and S/nBA copolymers as controls. The n-alkyl acrylate random copolymers exhibit enhanced glass transition breadths over narrow composition bands that correspond to autonomous self-healing. In contrast, S/EHA copolymers exhibit much greater glass transition breadths than S/nHA and S/nBA copolymers at all compositions tested as well as self-healing of damage over a broad composition range with full tensile-property recovery, often in 3-10 h. Characterization of glass transition breadth may serve as a simple screening tool for identifying copolymers that exhibit broad-composition-range, facile, autonomous self-healing and contribute to polymer resilience and sustainability.
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Affiliation(s)
- Tong Wang
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Wenshiue O Young
- The Dow Chemical Company, 400 Arcola Road, Collegeville, PA, 19426, USA
| | - Mathew J Suazo
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Asghar Peera
- The Dow Chemical Company, 400 Arcola Road, Collegeville, PA, 19426, USA
| | | | - Kimy Yeung
- The Dow Chemical Company, 400 Arcola Road, Collegeville, PA, 19426, USA
| | - Li Li
- The Dow Chemical Company, 400 Arcola Road, Collegeville, PA, 19426, USA
| | - John M Torkelson
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
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Serna S, Wang T, Torkelson JM. Eliminating the Tg-confinement and fragility-confinement effects in poly(4-methylstyrene) films by incorporation of 3 mol % 2-ethylheyxl acrylate comonomer. J Chem Phys 2024; 160:034903. [PMID: 38235797 DOI: 10.1063/5.0189409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 12/22/2023] [Indexed: 01/19/2024] Open
Abstract
Nanoconfined poly(4-methylstyrene) [P(4-MS)] films exhibit reductions in glass transition temperature (Tg) relative to bulk Tg (Tg,bulk). Ellipsometry reveals that 15-nm-thick P(4-MS) films supported on silicon exhibit Tg - Tg,bulk = - 15 °C. P(4-MS) films also exhibit fragility-confinement effects; fragility decreases ∼60% in going from bulk to a 20-nm-thick film. Previous research found that incorporating 2-6 mol % 2-ethylhexyl acrylate (EHA) comonomer in styrene-based random copolymers eliminates Tg- and fragility-confinement effects in polystyrene. Here, we demonstrate that incorporating 3 mol % EHA in a 4-MS-based random copolymer, 97/3 P(4-MS/EHA), eliminates the Tg- and fragility-confinement effects. The invariance of fragility with nanoconfinement of 97/3 P(4-MS/EHA) films, hypothesized to originate from the interdigitation of ethylhexyl groups, indicates that the presence of EHA prevents the free surface from perturbing chain packing and the cooperative mobility associated with Tg. This method of eliminating confinement effects is advantageous as it relies on the simplest of polymerization methods and neat copolymer only slightly altered in composition from homopolymer. We also investigated whether we could eliminate the Tg-confinement effect with low levels of 2-ethylhexyl methacrylate (EHMA) in 4-MS-based or styrene-based copolymers. Although EHMA is structurally nearly identical to EHA, 4-MS-based and styrene-based copolymers incorporating 4 mol % EHMA exhibit Tg-confinement effects similar to P(4-MS) and polystyrene. These results support the special character of EHA in eliminating confinement effects originating at free surfaces.
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Affiliation(s)
- Sergio Serna
- Department of Chemical and Biological Engineering, Evanston, Illinois 60208, USA
| | - Tong Wang
- Department of Chemical and Biological Engineering, Evanston, Illinois 60208, USA
| | - John M Torkelson
- Department of Chemical and Biological Engineering, Evanston, Illinois 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
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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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Chen B, Torkelson JM. Development of rigid amorphous fraction in cold‐crystallized syndiotactic polystyrene films confined near the nanoscale: Novel analysis via ellipsometry. JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1002/pol.20220056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Boran Chen
- Department of Chemical and Biological Engineering Northwestern University Evanston Illinois USA
| | - John M. Torkelson
- Department of Chemical and Biological Engineering Northwestern University Evanston Illinois USA
- Department of Materials Science and Engineering Northwestern University Evanston Illinois USA
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Chan JM, Kordon AC, Zhang R, Wang M. Direct visualization of bottlebrush polymer conformations in the solid state. Proc Natl Acad Sci U S A 2021; 118:e2109534118. [PMID: 34599105 PMCID: PMC8501853 DOI: 10.1073/pnas.2109534118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2021] [Indexed: 12/28/2022] Open
Abstract
Although the behavior of single chains is integral to the foundation of polymer science, a clear and convincing image of single chains in the solid state has still not been captured. For bottlebrush polymers, understanding their conformation in bulk materials is especially important because their extended backbones may explain their self-assembly and mechanical properties that have been attractive for many applications. Here, single-bottlebrush chains are visualized using single-molecule localization microscopy to study their conformations in a polymer melt composed of linear polymers. By observing bottlebrush polymers with different side chain lengths and grafting densities, we observe the relationship between molecular architecture and conformation. We show that bottlebrushes are significantly more rigid in the solid state than previously measured in solution, and the scaling relationships between persistence length and side chain length deviate from those predicted by theory and simulation. We discuss these discrepancies using mechanisms inspired by polymer-grafted nanoparticles, a conceptually similar system. Our work provides a platform for visualizing single-polymer chains in an environment made up entirely of other polymers, which could answer a number of open questions in polymer science.
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Affiliation(s)
- Jonathan M Chan
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208
| | - Avram C Kordon
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208
| | - Ruimeng Zhang
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208
| | - Muzhou Wang
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208
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Zhang W, Douglas JF, Chremos A, Starr FW. Structure and Dynamics of Star Polymer Films from Coarse-Grained Molecular Simulations. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c00504] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wengang Zhang
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, United States
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Francis W. Starr
- Department of Physics, Wesleyan University, Middletown, Connecticut 06459, United States
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