Stimuli-responsive polymers with changeable fluorescent properties have numerous applications in sensing, bioimaging, and detection. Here we describe the facile synthesis of a pH-responsive amphiphilic asymmetric diblock copolymer of acrylic acid and butyl acrylate that incorporates a polarity-sensitive fluorophore. The asymmetric structure enhances the stimuli-responsive behavior: as the environmental pH decreases, the fluorescent intensity of the asymmetric diblock copolymer gradually increases, whereas its symmetric block counterpart shows limited and stepwise change. Besides, this remarkable difference was demonstrated to be concentration-independent, as similar emission behavior was found for both polymers at lower concentrations. These results indicate that the fluorescence properties of the copolymer can be adjusted by rationally designing the copolymer structure. This work provides a novel and general strategy for the design and synthesis of polymeric materials with encapsulated structures showing stimuli-responsive fluorescent properties to be applied as fluorescent probes with a smoothly varying response curve rather than the simple on–off switch that is typical of block copolymer systems.

中文翻译：

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具有 pH 响应荧光特性的两亲不对称二嵌段共聚物

具有可变荧光特性的刺激响应聚合物在传感、生物成像和检测方面有许多应用。在这里，我们描述了一种简单的合成丙烯酸和丙烯酸丁酯的 pH 响应两亲不对称二嵌段共聚物，该共聚物包含极性敏感的荧光团。不对称结构增强了刺激响应行为：随着环境 pH 值的降低，不对称二嵌段共聚物的荧光强度逐渐增加，而其对称嵌段对应物表现出有限的逐步变化。此外，这种显着差异被证明与浓度无关，因为两种聚合物在较低浓度下都发现了相似的发射行为。这些结果表明，可以通过合理设计共聚物结构来调节共聚物的荧光性能。这项工作为设计和合成具有显示刺激响应荧光特性的封装结构的聚合物材料提供了一种新颖且通用的策略，可用作具有平滑变化响应曲线的荧光探针，而不是典型的块状简单开关共聚物系统。