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Jeong H, Gu J, Mwasame P, Patankar K, Yu D, Sing CE. Modeling the competition between phase separation and polymerization under explicit polydispersity. SOFT MATTER 2024; 20:681-692. [PMID: 38164983 DOI: 10.1039/d3sm01411h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The dynamics of phase separation for polymer blends is important in determining the final morphology and properties of polymer materials; in practical applications, this phase separation can be controlled by coupling to polymerization reaction kinetics via a process called 'polymerization-induced phase separation'. We develop a phase-field model for a polymer melt blend using a polymerizing Cahn-Hilliard (pCH) formalism to understand the fundamental processes underlying phase separation behavior of a mixture of two species independently undergoing linear step-growth polymerization. In our method, we explicitly model polydispersity in these systems to consider different molecular-weight components that will diffuse at different rates. We first show that this pCH model predicts results consistent with the Carothers predictions for step-growth polymerization kinetics, the Flory-Huggins theory of polymer mixing, and the classical predictions of spinodal decomposition in symmetric polymer blends. The model is then used to characterize (i) the competition between phase separation dynamics and polymerization kinetics, and (ii) the effect of unequal reaction rates between species. For large incompatibility between the species (i.e. high χ), our pCH model demonstrates that the strength for phase separation directly corresponds to the kinetics of phase separation. We find that increasing the reaction rate k̃, first induces faster phase separation but this trend reverses as we further increase k̃ due to the competition between molecular diffusion and polymerization. In this case, phase separation is delayed for faster polymerization rates due to the rapid accumulation of slow-moving, high molecular weight components.
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Affiliation(s)
- Hyeonmin Jeong
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Junsi Gu
- Dow Chemical Company, Midland, MI, 48667, USA
| | | | | | - Decai Yu
- Dow Chemical Company, Midland, MI, 48667, USA
| | - Charles E Sing
- Department of Chemical and Biomolecular Engineering, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA.
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Yu R, Cao Y, Chen K, Li Y, Liu W, Li B, Li H, Yang Y. Light Intensity-Selective Photopolymerization and Photoisomerization for Creating Colorful Polymer-Stabilized Cholesteric Liquid Crystal Patterns. ACS APPLIED MATERIALS & INTERFACES 2022; 14:38228-38234. [PMID: 35960859 DOI: 10.1021/acsami.2c10763] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polymer-stabilized cholesteric liquid crystal (PSCLC) films have been widely studied for their application as sensors, polarizers, and reflective windows. However, the preparation of programmable and colorful patterns based on the structural color is still challenging. Herein, the photochromic CLC mixtures were prepared by adding a photoisomerizable chiral additive (CA) and a photoinitiator in the nematic liquid crystal LC242. Under UV irradiation with weak intensity, photoisomerization of the CA was carried out and photopolymerization was suppressed by oxygen inhibition. With extending the irradiation time, the helical pitch of the CLC film increased and the selective Bragg reflection band tended to redshift. Under strong UV irradiation, oxygen inhibition was overcome and photopolymerization dominates the reaction. Therefore, the colorful-patterned PSCLC films were able to be prepared using masks. The results shown here not only give us a better understanding of the effect of oxygen inhibition but also lay the foundations for practical applications such as decoration and optical devices.
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Affiliation(s)
- Runwei Yu
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Yu Cao
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Kai Chen
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Yi Li
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Wei Liu
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Baozong Li
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Hongkun Li
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
| | - Yonggang Yang
- State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Key Laboratory of Polymeric Materials Design and Synthesis for Biomedical Function, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
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