三聚氰胺/Tb3+插层的聚二炔纳米片的制备及其热致变色可逆性研究

聚二炔(PDA)是一类具有层状结构的共轭聚合物. 在插层过程中，客体组分可插入PDA的层间，形成插层结构. 在这些结构中，一部分插层复合物具有近乎完美的组装结构，并展现出完全可逆的热致变色特性. 迄今为止，已报到的具有近乎完美组装结构的PDA复合物中仅成功插入了单个客体组分. 本文选择其一侧的羧基可与Tb³⁺离子或三聚氰胺(MAs)作用的10，12-二十五烷二炔酸(PCDA)作为单体. 当PCDA，MA和Tb³⁺投料摩尔比为3:267:1时，虽然体系中存在大大过量的MA，仅有Tb³⁺离子插入了PDA层间，该复合物具有近乎完美插层结构，表现出完全可逆的热致变色特性. 当PCDA，MA和Tb³⁺投料摩尔比为3:267:0.6时，此时Tb³⁺和MAs都插入了PDA的层间，该复合物存在近乎完美的结构区域和一些不完美的缺陷区域(例如：MA插层区域以及区域-区域边界处). 因此，其仅表现出部分可逆的热致变色特性. 其近乎完美的结构区域中的共轭主链仍能可逆地恢复至其初始构象，而缺陷区域的共轭主链则很难可逆地恢复至其初始构象.

Fabrication of Melamine/Tb3+-Intercalated Polydiacetylene Nanosheets and Their Thermochromic Reversibility

Polydiacetylene (PDA) is one kind of the conjugated polymer with layered structure, which can serve as a host to accommodate the guest components through intercalation. In these in-tercalated PDAs, some of them were reported to have a nearly perfect organized structure and perform completely reversible thermochromism. Till now, these reported intercalated PDAs were made by only introducing a single component for intercalation. Here, we chose 10,12-pentacosadiynoic acid (PCDA) as the monomer, of which the carboxyl-terminal groups can interact with either Tb³⁺ ions or melamines (MAs). When the feeding molar ratio of PCDA, MA, and Tb³⁺ ion was 3:267:1, only Tb³⁺ ions were intercalated though excess MAs existed. Such Tb³⁺-intercalated poly-PCDA exhibited completely reversible thermochromism, where almost all the carboxyl groups interacted with Tb³⁺ ions to form the nearly perfect structure. When the feeding molar ratio of PCDA, MA, and Tb³⁺ ion was 3:267:0.6, both Tb³⁺ ions and MAs were intercalated. There existed some defects in the imperfect MA-intercalated domains and at the domain boundaries. The MA/Tb³⁺-intercalated poly-PCDA exhibits partially reversible thermochromism, where the backbones near the defects are hard to return the initial conformation, while the rest, those at nearly perfect organized domains, are still able to restore the initial conformation.