. 2021 Oct 9;13(20):3462. doi: 10.3390/polym13203462
© 2021 by the authors.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
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| Comp | 21a | 21b | 21c | 21d |
| R | H | CH3 | OCH3 | OC2H5 |
