Zhang Yi, Wang Ruijia, Lu Wei, Li Wanning, Chen Si, Chen Tao
College of Material Science and Engineering, Zhejiang University of Technology Hangzhou 310014 Zhejiang China
Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences Ningbo 315201 China
Nanoscale Adv. 2022 Dec 14;5(3):725-732. doi: 10.1039/d2na00757f. eCollection 2023 Jan 31.
Aggregation-induced emissive fluorogens (AIEgens) are promising building blocks for fluorescent polymeric hydrogels (FPHs) because intense fluorescence intensities are usually guaranteed by spontaneous aggregates of hydrophobic AIEgens in a hydrophilic polymer network. However, most AIE-active FPHs are single-color fluorescent and cannot display tunable emission colors. Additionally, efforts to produce mechanically strong AIE-active hydrogels have been largely ignored, restricting their potential uses. Herein, we present the synthesis of an AIE-active methyl picolinate-substituted 1,8-naphthalimide monomer (MP-NI) for fabricating mechanical tough and multicolor FPHs. Owing to the introduction of bulky and coordinative methyl picolinate group, these specially designed MP-NI molecules were forced to adopt propeller-shaped conformation that renders them with intense aggregation-induced blue emission. Moreover, the MP-NI moieties grafted in a hydrogel matrix can sensitize red and green fluorescence of Euand Tb antenna effect. Consequently, multicolor fluorescent hydrogels that sustain a high stress of 1 MPa were obtained by chemically introducing MP-NI moieties into dually cross-linked alginate polymer networks with high-density metal (Ca/Tb/Eu) coordination and hydrogen bonding crosslinks. Their capacity to enable the writing of arbitrary multicolor fluorescent patterns using Eu/Tb as inks were finally demonstrated, suggesting their potential uses for smart display and information encryption.
聚集诱导发光荧光团（AIEgens）是用于荧光聚合物水凝胶（FPHs）的有前景的构建基元，因为在亲水性聚合物网络中，疏水性AIEgens的自发聚集通常能保证强烈的荧光强度。然而，大多数具有AIE活性的FPHs是单色荧光的，无法呈现可调谐的发射颜色。此外，制备机械强度高的具有AIE活性的水凝胶的工作在很大程度上被忽视了，这限制了它们的潜在用途。在此，我们展示了一种用于制备机械坚韧且多色FPHs的具有AIE活性的甲基吡啶甲酸酯取代的1,8-萘二甲酰亚胺单体（MP-NI）的合成。由于引入了庞大且具有配位性的甲基吡啶甲酸酯基团，这些经过特殊设计的MP-NI分子被迫采取螺旋桨状构象，使其具有强烈的聚集诱导蓝色发射。此外，接枝在水凝胶基质中的MP-NI部分可以通过天线效应敏化Eu和Tb的红色和绿色荧光。因此，通过将MP-NI部分化学引入具有高密度金属（Ca/Tb/Eu）配位和氢键交联的双交联藻酸盐聚合物网络中，获得了能承受1 MPa高应力的多色荧光水凝胶。最终展示了它们使用Eu/Tb作为墨水书写任意多色荧光图案的能力，表明它们在智能显示和信息加密方面的潜在用途。
