Construction of triblock copolyesters via one-step switchable terpolymerization of epoxides, phthalic anhydride and ε-caprolactone using dual urea/organic base catalysts was written by Lin, Limiao;Chen, Xin;Xiang, Huanxin;Chang, Min;Xu, Yonghang;Zhao, Hongting;Meng, Yuezhong. And the article was included in Polymer Chemistry in 2022.Quality Control of 1,3-Dicyclohexylurea This article mentions the following:
In this study, triblock copolyesters were synthesized via a switchable terpolymn. of mixed monomers of epoxides, phthalic anhydride (PA) and ε-caprolactone (CL) by using cost-effective dual urea/organic base catalysts. Different combinations of urea/organic base pairs were evaluated in order to optimize the catalytic activity and switchable selectivity, and different types of epoxides were employed to obtain diverse copolyesters. The sequence structures of the obtained copolyesters were analyzed by gel permeation chromatog. and diffusion-ordered NMR spectroscopy (DOSY) measurements. The switchable mechanism of the ROP of lactones and ROAC of epoxide/anhydride cycles was investigated via in situ anal. of 1H NMR, GPC and ATR-IR spectroscopy. The results showed that the N,N’-dicyclohexylurea (U1)/bis(triphenylphosphine)iminium chloride (PPNCl) pair with more alk. urea exhibited the highest catalytic activity for the mixture of cyclohexene oxide, PA and CL in both ring-opening alternating copolymerization (ROAC) and ring-opening polymerization (ROP) reaction cycles as compared to those previously reported. It was found that the existence/exhaustion of PA could be considered to be the switch between ROAC and ROP reaction cycles, and that the superior catalytic selectivity contributed to the successful formation of the desired triblock sequence structures. In the experiment, the researchers used many compounds, for example, 1,3-Dicyclohexylurea (cas: 2387-23-7Quality Control of 1,3-Dicyclohexylurea).
1,3-Dicyclohexylurea (cas: 2387-23-7) belongs to amides. The solubilities of amides and esters are roughly comparable. Typically amides are less soluble than comparable amines and carboxylic acids since these compounds can both donate and accept hydrogen bonds. Tertiary amides, with the important exception of N,N-dimethylformamide, exhibit low solubility in water. Ionic, or saltlike, amides are strongly alkaline compounds ordinarily made by treating ammonia, an amine, or a covalent amide with a reactive metal such as sodium.Quality Control of 1,3-Dicyclohexylurea
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