Synthesis, structures and multifunctional sensory properties of poly[2,7-(9,9-dihexylfluorene)]-block-poly[2-(dimethylamino)ethyl methacrylate] rod-coil diblock copolymers
作者:Sung-Tso Lin、Yi-Chih Tung、Wen-Chang Chen
DOI:10.1039/b807118g
日期:——
The synthesis, structures and multifunctional sensory properties of amphiphilic poly[2,7-(9,9-dihexylfluorene)]-block-poly[2-(dimethylamino)ethyl methacrylate] (PF-b-PDMAEMA) rod-coil diblock copolymers are reported. The new copolymers, with PDMAEMA coil lengths of 31, 45, 93 and 185 repeating units, were synthesized by atom transfer radical polymerization. The surface structures and photophysical properties of the synthesized polymers were studied through the variation of solvent composition (water–THF), temperature, and pH. The PF7-b-PDMAEMA45 structure changed from spheres to separate cylinders, bundles of cylinders and spiral-shaped micelles as the solvent composition changed from 0 to 90 wt% water in THF. However, the long-range order structure of spiral-shaped loops was not observed at a long coil length. The micellar aggregates of PF7-b-PDMAEMA45 in water showed a reversible surface structure transformation from cylinder-bundles to spheres on heating from 25 to 75 °C. The variation of the micelle size with temperature was judged to be similar from both atomic force microscopy (AFM) and dynamic light scattering (DLS) measurements. The intermolecular PF aggregations led to fluorescence quenching and a blue-shift in the absorption spectra of the block copolymer as the water content increased. The photoluminescence (PL) intensity of PF7-b-PDMAEMA45 in water was thermoreversible based on its lower critical solution temperature. The PL characteristics suggested the new copolymers behave as an on/off fluorescence indicator of temperature or pH, with a reversible “on–off” profile at an elevated temperature in water: the pH–fluorescence intensity profile switched from “off–on” to “on–off” as the temperature increased. The present study suggests that PF-b-PDMAEMA copolymers have potential applications as multifunctional sensory materials toward solvent, temperature, and pH.
两亲性聚[2,7-(9,9-二己基芴)]-嵌段-聚[2-(二甲基氨基)乙基甲基丙烯酸酯](PF-b-PDMAEMA)棒状线圈二嵌段共聚物的合成、结构和多功能感官性能报道称。通过原子转移自由基聚合合成了 PDMAEMA 线圈长度为 31、45、93 和 185 个重复单元的新型共聚物。通过溶剂成分(水-THF)、温度和 pH 值的变化,研究了合成聚合物的表面结构和光物理性质。当溶剂组成从 0 wt% 水的 THF 溶液变为 90 wt% 水时,PF7-b-PDMAEMA45 结构从球形变为单独的圆柱体、圆柱束和螺旋形胶束。然而,在长线圈长度下没有观察到螺旋形环的长程有序结构。 PF7-b-PDMAEMA45 在水中的胶束聚集体在从 25 °C 加热至 75 °C 时表现出从圆柱束到球体的可逆表面结构转变。通过原子力显微镜(AFM)和动态光散射(DLS)测量,胶束尺寸随温度的变化被认为是相似的。随着水含量的增加,分子间 PF 聚集导致嵌段共聚物的荧光猝灭和吸收光谱蓝移。由于其较低的临界溶液温度,PF7-b-PDMAEMA45 在水中的光致发光 (PL) 强度是热可逆的。 PL 特性表明,新型共聚物可作为温度或 pH 值的开/关荧光指示剂,在水中高温下具有可逆的“开-关”曲线:pH-荧光强度曲线从“关-开”切换为“关-开”。随着温度升高而“开-关”。本研究表明,PF-b-PDMAEMA 共聚物作为溶剂、温度和 pH 值的多功能传感材料具有潜在的应用前景。