Photoregulated Structural Memory in Supramolecular Polymers

Memory is a central principle underlying adaptive behavior in biological systems and an important source of inspiration for the design of functional artificial materials. While memory effects have been widely realized in macroscopic materials and devices, whether comparable behavior can arise from dynamic molecular organization remains largely unexplored. In supramolecular polymers (SPs), memory has thus far been demonstrated primarily in the form of chiral memory, while other types of memory, such as structural memory─where supramolecular organization is retained despite changes at the molecular level─remain largely unexplored. Here, we demonstrate structural memory in SPs through light-driven control over self-assembly pathways. We introduce a photoswitchable dithienylethene-based molecular building block capable of reversible interconversion between open- and closed-ring isomers both in the monomeric and assembled state. Although both isomers undergo supramolecular polymerization into elongated one-dimensional fibers in methylcyclohexane, they differ markedly in their aggregation propensity and resulting morphology (rigid, bundled fibers for the open form vs flexible, individual fibers for the closed form). By controlling the sequence of photoirradiation and supramolecular polymerization, we obtain pathway-dependent supramolecular architectures that retain features of their formation history despite changes at the molecular level. These results establish a route toward SPs capable of storing pathway information and advance the design of history-dependent adaptive soft matter.