Chen Guoneng, Lin Riyan, Lei Yanshi, Cai Peng, Huang Yifu, Zhang Hefeng
Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, College of Chemistry and Chemical Engineering, Shantou University, Shantou 515063, People's Republic of China.
Soft Matter. 2023 Dec 13;19(48):9470-9477. doi: 10.1039/d3sm01055d.
The photocuring technology based on thiol-ene click reaction can be easily applied for copolymerizing or crosslinking the acrylate monomers for ionogels. However, there is still a problem: when the acrylate monomers contain the popular spiropyran as the stimuli-responsive group, it should be concerned about the participation of the active CC bond from the ring-opened spiropyran during a thiol-ene reaction, which may in turn affect the stimuli-responsiveness of the spiropyran. Up to now, the structure and properties of spiropyran-containing ionogels in this case have still not been well investigated. Therefore, in this work we carefully study a new spiropyran-containing polyurethane ionogel by crosslinking an acrylate-terminated, spiropyran-containing polyurethane prepolymer and a polythiol in ionic liquid through thiol-ene chemistry. It is found for the first time that, during constructing an ionogel, the coexistence of a reversible thiol-ene reaction between the CC bond from the ring-opened spiropyran and the thiol group can bring about a different reverse photochromic behavior. The proposed mechanism of the abnormal photochromism is analyzed. In addition, it is also observed that the thiol-ene chemistry can incorporate photomechanical and photoconductive properties into the new spiropyran-containing ionogel.
基于硫醇-烯点击反应的光固化技术可轻松用于使离子凝胶的丙烯酸酯单体共聚或交联。然而，仍存在一个问题：当丙烯酸酯单体含有常见的螺吡喃作为刺激响应基团时，在硫醇-烯反应过程中应关注开环螺吡喃的活性碳-碳键的参与情况，这可能反过来影响螺吡喃的刺激响应性。到目前为止，这种情况下含螺吡喃离子凝胶的结构和性能仍未得到充分研究。因此，在这项工作中，我们通过硫醇-烯化学方法，使含丙烯酸酯端基、含螺吡喃的聚氨酯预聚物与离子液体中的多硫醇交联，仔细研究了一种新型含螺吡喃的聚氨酯离子凝胶。首次发现，在构建离子凝胶过程中，开环螺吡喃的碳-碳键与硫醇基团之间可逆的硫醇-烯反应的共存会导致不同的逆光致变色行为。分析了所提出的异常光致变色机理。此外，还观察到硫醇-烯化学可将光机械和光电导性能引入新型含螺吡喃离子凝胶中。
