Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers
Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers
复制标题
DOI：
10.1002/adfm.201703952
复制
发表时间：
2018-01-04
影响因子：
19
通讯作者：
Meijer, E. W.
中科院分区：
文献类型：
--
作者：
Zha, R. Helen;Vantomme, Ghislaine;Meijer, E. W.
具有高度有序分子排列的材料具有从其纳米级结构衍生的独特性质的能力。在这里，描述了偶氮苯(AZO)官能化的离散长度的硅氧烷齐聚物的合成和表征，它们形成了可光切换的超分子材料。具体地说，相分离和偶氮苯结晶之间的协同作用导致了剥离的2D晶体的自组装，该晶体在紫外光下发生光异构化后变得各向同性。因此，由于相分离促进了出人意料的快速2D结晶，材料经历了快速的无热固-液转变，这种转变可以用蓝光逆转。相反，通过氢键实现遥控超分子聚合抑制了偶氮苯的结晶，仅基于相分离就可以获得形貌良好的纳米结构浆料，从而表现出嵌段共聚物的行为。因此，通过在偶氮苯功能化的硅氧烷齐聚物中调节自组装力的平衡，可以设计出具有各种机械性能的快速和可逆相变材料，用于光刻或可切换的粘附性到润滑剂的性能。
Materials with highly ordered molecular arrangements have the capacity to display unique properties derived from their nanoscale structure. Here, the synthesis and characterization of azobenzene (AZO)-functionalized siloxane oligomers of discrete length that form photoswitchable supramolecular materials are described. Specifically, synergy between phase segregation and azobenzene crystallization leads to the self-assembly of an exfoliated 2D crystal that becomes isotropic upon photoisomerization with UV light. Consequently, the material undergoes a rapid athermal solid-to-liquid transition which can be reversed using blue light due to the unexpectedly fast 2D crystallization that is facilitated by phase segregation. In contrast, enabling telechelic supramolecular polymerization through hydrogen bonding inhibits azobenzene crystallization, and nanostructured pastes with well-ordered morphologies are obtained based on phase segregation alone, thus demonstrating block copolymer-like behavior. Therefore, by tailoring the balance of self-assembly forces in the azobenzene-functionalized siloxane oligomers, fast and reversible phase-changing materials can be engineered with various mechanical properties for applications in photolithography or switchable adhesion to lubricant properties.