科研之友
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摘要
Three kinds of well-defined topological azo-polymers with controlled molecular weights are prepared using an acrylate-functionalized cyclic polymeric azo-precursor by a selective head-to-tail acyclic diene metathesis (ADMET) polymerization. First, a multifunctional linear precursor bearing the terminal alkyne, hydroxyl, and azido groups were elaborately synthesized. A well-defined acrylate-containing monocyclic azo-polymer was then prepared via "click" ring closure and esterification, which can be considered a selective macromolecular chain stopper in the subsequent ADMET polymerizations of three different types of azo-functionalized monomers. Finally, azo-polymers with cyclic-linear, cyclic-linear-cyclic, and cyclic-hyperbranched topologies were successfully constructed, respectively. Interestingly, these prepared azo-polymers show distinct and unusual photoresponsive behaviors.
