Kametani Yuki, Nishijima Ami, Hiramoto Shu, Uemura Takashi
Institute of Engineering Innovation, School of Engineering, The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan
Department of Applied Chemistry Graduate School of Engineering, The University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo 113-8656 Japan.
Chem Sci. 2025 May 12. doi: 10.1039/d5sc02118a.
Materials with ultimately thin (2D) or narrow (1D) structures have gained significant attention due to their exceptional properties. However, decreasing the dimensionality of soft polymer materials has been a formidable challenge due to the lack of rational synthetic methodology. Here, we performed cross-linking polymerization inside metal-organic frameworks (MOFs) as nanoporous scaffolds to afford poly(-isopropylacrylamide) (PNIPAm) with unprecedented 1D and 2D network topologies: double strands and monolayer sheets. Remarkably, these polymer networks exhibited unique thermoresponsive properties in water that were strongly correlated with their specific topologies. Note that the transition temperature of double-stranded PNIPAm is among the lowest of known PNIPAm materials. The monolayer PNIPAm sheets exhibit a markedly slow thermal response over a wide temperature range. The dimensional constraint imposed on cross-linking by MOF-templated polymerization enables precisely controlling the chain orientation and proximity, providing new insights into the mechanism of the PNIPAm phase transition.
具有极致薄（二维）或窄（一维）结构的材料因其卓越性能而备受关注。然而，由于缺乏合理的合成方法，降低软质聚合物材料的维度一直是一项艰巨的挑战。在此，我们在作为纳米多孔支架的金属有机框架（MOF）内部进行交联聚合，以获得具有前所未有的一维和二维网络拓扑结构的聚（N-异丙基丙烯酰胺）（PNIPAm）：双链和单层片材。值得注意的是，这些聚合物网络在水中表现出独特的热响应特性，且与其特定拓扑结构密切相关。请注意，双链PNIPAm的转变温度在已知PNIPAm材料中是最低的之一。单层PNIPAm片材在很宽的温度范围内表现出明显缓慢的热响应。MOF模板聚合对交联施加的尺寸限制能够精确控制链的取向和间距，为PNIPAm相变机制提供了新的见解。
