Interplay of Molecular and Environmental Design in Supramolecular Polymerization

Supramolecular polymerization offers a powerful strategy to construct polymer-like architectures from well-defined molecular building blocks through reversible noncovalent interactions. The dynamic nature of these interactions enables responsiveness, adaptability, and the formation of complex hierarchical structures. At the same time, it makes supramolecular polymerization highly sensitive to its chemical and physical environment. As a result, the structure and properties of supramolecular polymers arise not only from molecular design, but also from the conditions under which self-assembly takes place. This thesis explores how molecular design and environmental parameters together govern supramolecular polymerization, and how environmental factors can be used as design tools to steer assembly pathways, control hierarchical organization, and access functional states. Using helical supramolecular polymers as model systems, and circular dichroism (CD) spectroscopy as a central technique, this work shows that environmental control is not merely a secondary effect, but a key element in supramolecular polymer design. Chapter 1 introduces supramolecular polymerization as a context-dependent process that can be described by a multidimensional free-energy landscape, in which multiple assembly pathways and structural states can coexist. External parameters such as solvent, temperature, additives, confinement, and applied stimuli reshape this landscape, thereby influencing both the thermodynamics and kinetics of self-assembly. This perspective positions environmental control alongside molecular design as a central principle in supramolecular polymerization. In Chapter 2, the role of molecular design is studied using constitutional isomers of amide-functionalized hexaazatrinaphthylene (HATNA). Although the isomers have similar electronic and optical properties, small differences in symmetry and functional group positioning lead to distinct hydrogen-bonding patterns and packing modes. These differences influence how the assemblies interact with their solvent environment, resulting in clear changes in supramolecular morphology. These findings show that molecular design not only controls intermolecular interactions, but also affects how assemblies interact with their surroundings. Chapter 3 focuses on actively modifying the environment by introducing macromolecular crowding as a physical parameter in supramolecular polymerization. By systematically varying both monomer design and macromolecular environment, including crowder concentration, size, architecture, and chemical compatibility, it is shown that crowding increases the effective concentration and can induce supramolecular polymerization. At the same time, it alters the available assembly pathways and the resulting structures. Macromolecular crowding therefore not only triggers assembly, but also influences how supramolecular structures form and develop. Building on this concept, Chapter 4 addresses the challenge of transferring supramolecular polymers from solution to the solid state. An in situ photopolymerization strategy is developed in which supramolecular assemblies are embedded within a cross-linked (meth)acrylate matrix that rapidly forms around them. In contrast to macromolecular crowding, where the environment remains dynamic, the matrix immobilizes the structures and protects them from external perturbations. This approach preserves the structural and chiroptical properties of the assemblies in the solid state. In Chapter 5, solvent effects are explored through solvent-induced stereomutation of supramolecular helicity. By systematically analyzing helicity across a wide range of solvents and mapping it as a function of Hansen solubility parameters (HSP), distinct solvent regimes corresponding to opposite supramolecular handedness are identified. This approach shows that supramolecular chirality is not solely determined by molecular structure, but arises from a reproducible interplay between dispersion, polarity, and hydrogen-bonding interactions with the solvent. As such, the solvent environment consistently modulates supramolecular helicity, establishing HSP mapping as a general strategy to explain and predict solvent-controlled chirality. Chapter 6 extends the concept of environmental control to the photonic domain by introducing vibrational strong coupling (VSC) as a tunable parameter in supramolecular polymerization. By coupling molecular vibrations to confined optical cavity modes, the thermodynamics of polymerization can be selectively modulated, resulting in either stabilization or destabilization of the assembled state. In this way, VSC offers a new route to control supramolecular stability by modifying the confined electromagnetic environment. Finally, the epilogue reflects on the broader implications of these findings. Supramolecular polymerization can be viewed as an emergent process arising from the interplay between molecular design and environmental conditions. By systematically incorporating environmental parameters into the design strategy, new opportunities emerge to control assembly pathways, create complex structures, and develop functional supramolecular materials.