期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 139, 期 25, 页码 8678-8684出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.7b03967
关键词
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资金
- NSFC [51522308, 201421061, 21232001]
- MOST [2017YFB0703300]
Polyurethanes (PUs) have many applications resulting from their preeminent properties, but being commonly used toxic catalysts, and the lack of processability for PU thermosets cause limitations. Herein, we report a new class of the PU-like dynamic covalent polymers, poly(oxime-urethanes) (POUs), which are prepared from the uncatalyzed polyaddition of multifunctional mimes and hexamethylene dlisocyanate (HDI) at ambient temperature. Kinetics studies reveal that almost complete polymerization (similar to 99% conversion) can be achieved in 3 h at 30 degrees C in dichloromethane (DCM), the most effective among the solvents evaluated, producing linear POUs with comparable molecular weights to, the catalyzed PUs. We find that the oxime-carbamate structures are reversible at about 100 degrees C through oxime-enabled transcarbathoylation via a thermally-dissociative Mechanism. The cross-linked POUs based on oxime carbamate bonds show efficient catalyst-free healable/recyclable properties. Density functional theory (DFT) calculations suggest that the fast oxime-urethanation and the mild thermoreversible nature are mediated by the characteristic nitrone tautomer of the oxime. Given widespread urethane-containing materials, POUs are of promising potential in applications-because of the excellent mechanical performances, facile preparation, and dynamic property without using catalysts.
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