We designed and synthesized hyperbranched polymers (HBPs) having diarylethene (DE) at branching points and having fluorene (FL) and DE derivatives between branching points in order to investigate the effect of the polymer structure to fluorescence on/off switching efficiency induced by the photochromic reaction of DE. First, HBP was synthesized by polymerization of an FL monomer (FL-St) in the presence of a DE monomer with reversible addition-fragmentation chain transfer unit (St-DE-RAFT) in the feed ratio of [FL-St]/[St-DE-RAFT] = 10. The fluorescence intensity of the resulting HBP decreased linearly as a function of the photocyclization conversion of DE. The change in the fluorescence intensity accompanied by the photochromic reactions indicates that one DE closed-ring isomer can quench 16.9 neighboring FL moieties. However, the switching rate and on/off contrast of fluorescence were relatively low because the number of FL in the polymer chain is much larger than that of DE. Therefore, we synthesized two types of HBPs having DE positioned not only at the branching points but also integrated in the polymer chains with different branching degrees. The fluorescence intensity of FL for such HBPs showed a non-linear dependence on the photocyclization conversion of DE, and a significant emission decrease with high on/off contrast even in low conversion was demonstrated. One DE closed-ring isomer quenched 5.4–6.4 F L moieties, whereas the fluorescence quantum yield in the “on” state was found to be around 0.15. The quenching of FL molecules is more pronounced for higher branching degrees in the polymers, indicating that DE closed-ring isomer can quench efficiently FL molecules when located within the polymer chains as well as at the branching points of the polymer.

我们设计并合成了在支化点具有二芳基乙烯（DE）且在支化点之间具有芴（FL）和DE衍生物的超支化聚合物（HBP），以研究聚合物结构对光致变色引发的荧光开/关转换效率的影响DE的反应。首先，通过在具有可逆加成-断裂链转移单元（St-DE-RAFT）的DE单体的存在下，以[FL-St] / [的进料比]的FL单体（FL-St）的聚合来合成HBP。 St-DE-RAFT] =10。得到的HBP的荧光强度随DE的光环化转化而线性下降。伴随光致变色反应的荧光强度的变化表明一种DE闭环异构体可以淬灭16.9个相邻的FL部分。然而，由于聚合物链中FL的数量远大于DE的数量，因此荧光的转换速率和开/关对比度相对较低。因此，我们合成了两种类型的HBP，它们的DE不仅位于分支点，而且以不同的分支度整合在聚合物链中。此类HBP的FL荧光强度显示出与DE的光环化转化率呈非线性关系，并且即使在低转化率下，具有高开/关对比度的荧光发射也显着降低。一种DE闭环异构体淬灭了5.4-6.4 F L部分，而“开”态的荧光量子产率约为0.15。FL分子的淬灭对于聚合物中较高的支化度而言更为明显，