Enhancing swelling kinetics of pNIPAM lyogels: The role of crosslinking, copolymerization, and solvent

Journal
Fluid phase equilibria  
Volume
597
Article Number
114462
Citation
Fluid Phase Equilibria 597: 114462 (2025)
Publisher DOI
10.1016/j.fluid.2025.114462
Scopus ID
2-s2.0-105004411000
Publisher
Elsevier
Is Supplemented By
10.15480/882.15062
Stimuli-responsive lyogels are known for their ability to undergo significant macroscopic changes when exposed to external stimuli. While thermo-responsive gels, such as poly-N-isopropylacrylamide (pNIPAM), have been extensively studied across various applications, solvent-induced swelling has predominantly been investigated in aqueous solutions. This study explores the tailoring of lyogel formulations for future applications by controlling their solvent-induced swelling behavior, comparing both homopolymeric and semi-interpenetrating polymer networks (semi-IPNs). It is structured in two parts: the first focuses on characterization techniques, including NMR relaxometry, swelling degree measurements, mechanical testing, and SEM analysis, while the second part delves into swelling kinetic analysis, applying solvent exchange as a stimulus for varying gel formulations and solvents. In contrast to most previous studies, the impact of chemical and physical crosslinking, as well as copolymer inclusion, on the swelling behavior and mechanical properties of lyogels in organic solvents is examined and compared with solvent-induced swelling kinetics measurements. The results demonstrate that increasing chemically crosslinking in homopolymers and physically crosslinking in semi-IPNs enhances mechanical stability, while improving mass transport properties and solvent exchange kinetics. However, increases degree of crosslinking results in a prolonged response time to the solvent exchange stimulus and a reduction in the overall swelling capacity of the lyogels. Furthermore, variations in solvent properties, including molecular size and diffusion rates, significantly influence the swelling kinetics, whereas smaller, faster-diffusing solvents leading to more pronounced solvent spillage effects. Our findings highlight the complex interplay between gel formulation, network structure, and solvent nature in determining the solvent-induced swelling kinetics of lyogels, providing insights into how these materials can be tailored for specific applications especially those requiring short response times and optimized mechanical properties.
Subjects
Polymer
Semi-IPN
Smart reactors
Solvent-induced
Stimuli-responsive gels
Swelling kinetics
DDC Class
541: Physical; Theoretical
620.1: Engineering Mechanics and Materials Science
660: Chemistry; Chemical Engineering
Funding(s)
SFB 1615 - SMARTe Reaktoren für die Verfahrenstechnik der Zukunft  
Projekt DEAL  
More Funding Information
This project is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB 1615 – 503850735.
Lizenz
https://creativecommons.org/licenses/by/4.0/
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 2025-10-15 05:46:25
The authors regret that a chemical compound was incorrectly named as sodium persulfate, which was not used. The compound is named in Section 2.1 (Materials), where it appears in the list of chemicals, in Section 2.2 (Gel formulation), where it is described as “Subsequently, 2.5 mg of sodium persulfate…”, and in Table S1 (List of used chemicals) in the Supplementary Information. The correct name of the chemical used in the analysis was sodium metabisulfite. The authors would like to apologise for any inconvenience caused.
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 2025-05-14 05:08:54
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