Abstract
We fabricated the doubly crosslinked gel, with internal stress by stretching the gel during the gelation reaction using tetra-PEG gels, which are formed by the AB type crosslink-coupling of two mutually reactive tetra-arm polyethylene glycol (PEG). In a doubly crosslinked gel, two networks having different reference states coexist with and balance each other, resulting in enhanced Young’s modulus and residual strain. We investigated these properties by tuning the time for the imposition of the stretching of the gels and the stretching ratio. The residual strain increased with increase in the time for the imposition of stretching and the stretching ratio. On the other hand, the Young’s modulus had a maximum value at a certain time for the imposition of the stretching of the gels and increased with increasing stretching ratio. These results were well explained by the balance between the strain energies of the first and second networks under the framework of the classical two-network theory, where the total strain energy is described as a simple sum of the energies of the first and second networks.
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Acknowledgements
This work was supported by the Japan Society for the Promotion of Science (JSPS) through the Grants-in-Aid for the Graduate Program for Leaders in Life Innovation (GPLLI), the International Core Research Center for Nanobio, the Core-to-Core Program A. Advanced Research Networks, the Grants-in-Aid for Young Scientists (A) Grant Number 23700555 (to TS), and Scientific Research (S) Grant Number 16746899 (to UC). This work was also supported by the Japan Science and Technology Agency (JST) through the Center of Innovation program (to UC) and the PREST (to TS).
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Katashima, T., Chung, Ui. & Sakai, T. Mechanical properties of doubly crosslinked gels. Polym J 51, 851–859 (2019). https://doi.org/10.1038/s41428-019-0203-6
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DOI: https://doi.org/10.1038/s41428-019-0203-6
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