可用外部刺激可逆地导入和擦除人工缺陷的掺杂的PNIPAM微凝胶胶体晶体

Colloidal crystals with artificially designed defects are required to achieve many of their technological applications, and external stimuli-responsivity can significantly enhance their control over light. It is still a challenge for the fabrication of such crystals, which usually requires special equipments and uses complicated techniques. Under this project we will use monodisperse PNIPAM microgels as host particles and P(NIPAM-AAc) microgel with the same size as dopant to fabricate doped colloidal crystals simply via co-crystallization. Because of their same size, the introduction of dopant will not influence the crystallization of the system. High quality doped crystals with various contents of dopant are expected to obtained. Also because of their same size, the as-prepared crystals will not show a defect state in their spectra, however, real artificial defects can be induced in situ by increasing pH, which allows the P(NIPAM-AAc) microgels to swell. These artificial defects can be "erased" reversibly when the pH value is adjusted back. Besides pH, other external stimuli, including physical ones, such as temperature and electricity, and chemical ones, such as glucose and Pb2+, can be used to induce and erase artificial defects in the doped microgel colloidal crystals. These colloidal crystals with artificial defects which can be induced and erased reversibly by an external stimulus will find applications in many areas, such as optical sensing and the control over spontaneous or stimulated emission.

向胶体晶体中引入人工缺陷是实现胶体晶体许多功能的基础，如能对外部刺激作出响应则更能增强其对光的控制。目前制备具有人工缺陷的胶体晶体多需特殊装备，方法繁琐复杂。本项目拟以单分散的PNIPAM微凝胶粒子为主体，掺以相同粒径的P(NIPAM-AAc)微凝胶，通过共结晶得到掺杂的PNIPAM微凝胶胶体晶体。由于掺杂剂与主体粒子粒径相同，掺杂剂的引入将不影响体系的结晶，并可以任何比例掺杂，得到有序程度高的掺杂晶体。同样由于掺杂剂与主体粒子粒径相同，这样的胶体晶体将不显示缺陷态，但可利用微凝胶的刺激响应性通过改变pH值原位地导入人工缺陷，并且将pH调回又可将人工缺陷"擦除"。在此基础上可进一步通过温度、电流等物理刺激以及葡萄糖、铅离子等化学刺激可逆地导入和擦除人工缺陷。这些可用外部刺激可逆地导入和擦除人工缺陷的胶体晶体可望应用于光学传感、自发或受激辐射的控制等领域。

向胶体晶体中引入人工缺陷是实现胶体晶体许多功能的基础，如能对外部刺激作出响应则更能增强其对光的控制。目前制备具有人工缺陷的胶体晶体多需特殊装备，方法繁琐复杂。本项目首次提出以单分散的 PNIPAM 微凝胶粒子为主体，掺以相同粒径的 P(NIPAM-AAc)微凝胶，通过共结晶得到P(NIPAM-AAc)微凝胶掺杂的 PNIPAM 微凝胶胶体晶体。由于掺杂剂与主体粒子粒径相同，掺杂剂的引入将不影响体系的结晶，可以任何比例掺杂，得到高度有序的掺杂晶体。同样由于掺杂剂与主体粒子粒径相同，这样的胶体晶体将不显示缺陷态，但利用微凝胶的刺激响应性通过外部刺激可原位地导入人工缺陷，再利用外部刺激可将人工缺陷可逆地“擦除”。利用这一原理,我们成功地设计制备了多种可用外部刺激可逆地导入和擦除人工缺陷的微凝胶胶体晶体。用于导入和擦除缺陷态的外部刺激包括pH、温度、葡萄糖等。进一步我们发展了可用外部刺激在受体缺陷态、无缺陷态和给体缺陷态三种状态可逆转化的掺杂微凝胶胶体晶体。初步探索了此类胶体晶体在光学传感方面的应用，利用掺杂微凝胶胶体晶体局部有序-无序转变导致的光学变化，提出了新的光学传感机理，成功地制备了可快速响应的葡萄糖水凝胶光学传感器。作为本项研究的基础，本项目还对微凝胶胶体晶体的组装进行了研究，首次制备了二元微凝胶胶体晶体，提出了多种制备二维微凝胶胶体晶体的新方法，实现了大面积高质量二维微凝胶胶体晶体的制备。此外本项目还在收缩型葡萄糖敏感微凝胶、微凝胶胶体分子等领域进行了探索。