Liu Hanbin, Yin Hongyao, Feng Yujun
Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, P.R. China.
State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu, P.R. China.
Des Monomers Polym. 2016 Dec 26;20(1):363-367. doi: 10.1080/15685551.2016.1270027. eCollection 2017.
Smart system employed CO gas as new trigger has been attracting enormous attention in recent years, but few monomers that are capable of switching their hydrophobicity/hydrophility upon CO stimulation have been reported. A novel CO responsive monomer, 4-vinylbenzyl amidine, is designed and synthesized in this work with -dimethylacetamide dimethyl acetal and 4-vinylbenzyl amine that is prepared through the Gabriel reaction. In bi-phase solvent of -hexane and water, the monomer dissolves in -hexane first and then transforms into water upon the CO treatment, indicating a hydrophobic to hydrophilic transition. This transformation is demonstrated as reversible by monitoring the conductivity variation of its wet dimethyl formamide solution during alternate bubbling/removing CO. The protonation of 4-vinylbenzyl amidine upon CO treatment is demonstrated by H NMR which also accounts for the dissolubility change. The reversible addition-fragmentation chain-transfer polymerization of this monomer is also performed, finding the reaction only occurs in glacial acetic acid. The reason can be ascribed to the different radical structure produced in different solvent.
近年来，采用一氧化碳（CO）气体作为新触发剂的智能系统备受关注，但鲜有报道能够在CO刺激下切换其疏水性/亲水性的单体。在本工作中，通过加布里埃尔反应制备的N,N-二甲基乙酰胺二甲基缩醛和4-乙烯基苄胺，设计并合成了一种新型的CO响应单体4-乙烯基苄脒。在正己烷和水的双相溶剂中，该单体首先溶解于正己烷，经CO处理后转变为溶于水，表明发生了从疏水到亲水的转变。通过监测其湿二甲基甲酰胺溶液在交替鼓泡/去除CO过程中的电导率变化，证明这种转变是可逆的。1H NMR证实了4-乙烯基苄脒在CO处理后发生质子化，这也解释了溶解性的变化。还进行了该单体的可逆加成-断裂链转移聚合反应，发现该反应仅在冰醋酸中发生。原因可归因于在不同溶剂中产生的不同自由基结构。
