Thermally bisignate supramolecular polymerization
Thermally bisignate supramolecular polymerization
复制标题
DOI：
10.1038/nchem.2812
复制
发表时间：
2017-11-01
期刊：
影响因子：
21.8
通讯作者：
Aida, Takuzo
中科院分区：
文献类型：
--
作者：
Rao, Kotagiri Venkata;Miyajima, Daigo;Aida, Takuzo
超分子聚合物的诱人特性之一是其热力学可逆性，这对于刺激响应应用尤其有吸引力。这些聚合物通常在加热时分解，但在这里我们报道了在加热和冷却时发生的超分子聚合。这种行为源于使用带有八个含酰胺侧链的基于金属卟啉的定制单体，该单体通过π堆积和多价氢键相互作用组装成高度热稳定的一维聚合物，并在十二烷基溶剂中使用清除剂1-己醇。在 50 摄氏度左右，清除剂通过竞争性氢键将单体锁定为不可聚合的形式。冷却时，清除剂优先自聚集，释放单体进行聚合。加热还可以通过破坏偶极子和与清除剂的氢键相互作用来释放单体进行聚合。类似于共价键聚合物的“上限和下限临界溶液温度现象”，这种热双峰特征可能会导致超分子聚合物具有定制的复杂热响应特性。
One of the enticing characteristics of supramolecular polymers is their thermodynamic reversibility, which is attractive, in particular, for stimuli-responsive applications. These polymers usually disassemble upon heating, but here we report a supramolecular polymerization that occurs upon heating as well as cooling. This behaviour arises from the use of a metalloporphyrin-based tailored monomer bearing eight amide-containing side chains, which assembles into a highly thermostable one-dimensional polymer through pi-stacking and multivalent hydrogen-bonding interactions, and a scavenger, 1-hexanol, in a dodecane-based solvent. At around 50 degrees C, the scavenger locks the monomer into a non-polymerizable form through competing hydrogen bonding. On cooling, the scavenger preferentially self-aggregates, unlocking the monomer for polymerization. Heating also results in unlocking the monomer for polymerization, by disrupting the dipole and hydrogen-bonding interactions with the scavenger. Analogous to 'upper and lower critical solution temperature phenomena' for covalently bonded polymers, such a thermally bisignate feature may lead to supramolecular polymers with tailored complex thermoresponsive properties.