Journal article
Kinetically Limited Bulk Polymerization of Polymer Thin Films by Initiated Chemical Vapor Deposition
Macromolecules, v 56(24), pp 10111-10118
26 Dec 2023
PMID: 38161326
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
An experimental study and kinetic model analysis of the initiated chemical vapor deposition (iCVD) of polymer thin films have been performed at saturated monomer vapor conditions. Previous iCVD kinetic studies have focused on subsaturated monomer conditions where polymer deposition kinetics is known to be limited by monomer adsorption. However, iCVD kinetics at saturated conditions have so far not been systematically investigated, and it remains unclear whether the adsorption-limited phenomenon would still apply at saturation, given the abundance of monomer for reaction. To probe this question, a series of depositions of poly(vinylpyrrolidone) (PVP) thin films as a model system were performed by iCVD at substrate temperatures from 10 to 25 °C at both fully saturated (100%) and subsaturated (50%) conditions. While the deposition rates at subsaturated conditions exhibit the expected adsorption-limited behavior, the deposition rates at saturated conditions unexpectedly show two distinct deposition regimes with reaction time: an initial adsorption-limited regime followed by a kinetically limited steady-state regime. In the steady-state regime, the deposition kinetics is found to be thermally activated by raising substrate temperature with an overall activation energy of +86 kJ/mol, which agrees reasonably well with the experimentally determined value of +89 kJ/mol in the literature for bulk PVP polymerization and a mechanistically derived value of +91 kJ/mol based on the bulk free radical polymerization mechanism of PVP. These findings open new operating windows for iCVD polymerization and thin-film growth in which fast polymer deposition can be achieved without substrate cooling that can greatly simplify the iCVD scale-up to roll-to-roll processing and enable iCVD polymerization of highly volatile monomers relevant for diverse applications in biomedicine, smart wearables, and renewable energy.
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Details
- Title
- Kinetically Limited Bulk Polymerization of Polymer Thin Films by Initiated Chemical Vapor Deposition
- Creators
- Varun S Prasath - Rowan UniversityKenneth K S Lau - Rowan University
- Publication Details
- Macromolecules, v 56(24), pp 10111-10118
- Publisher
- American Chemical Society (ACS)
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemical and Biological Engineering
- Web of Science ID
- WOS:001132842300001
- Scopus ID
- 2-s2.0-85180089487
- Other Identifier
- 991021811752204721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Polymer Science