Supramolecular polymers arise from the self-assembly of distinct monomeric building blocks that engage in directed non-covalent interactions. By applying external stimuli that transiently weaken these interactions, the building blocks can undergo reversible disassembly, endowing the resulting materials with useful responsive functionalities. In this presentation, we showcase recent advances in leveraging supramolecular self-assembly to engineer polymer films with tailored mechanical properties and dynamic responsiveness. We introduce a strategy that blends two distinct building blocks in controlled ratios, enabling enhanced mechanical performance and spatially modulated behaviors that mimic the anisotropic properties of complex natural materials. Furthermore, we present new supramolecular design approaches for materials that generate distinct optical signals in response to mechanical deformation. By directly linking molecular-level changes in supramolecular binding to macroscopic material behavior, our approach provides a means to probe assembly and disassembly processes as influenced by cross-linker content, processing history, and external stimuli. This presentation will highlight how these responsive motifs serve as powerful tools for the in-situ investigation of dynamic assembly mechanisms in supramolecular systems, offering new insights into their mechanoresponsive properties.

Thermoresponsive polymers have several potential applications.[1] Thermal behavior (such as the Low Critical Solubilization Temperature) depends on the material's nature and architecture, affecting its use and performance. It is well established that hydrophilic/hydrophobic balance is a key factor that defines copolymer thermal behavior.[2] On the other hand, the aggregation state also affects the cloud point.[3]
Here, Reversible Addition-Fragmentation Chain Transfer (RAFT) was used to generate, continuously and in the same pot, two series of poly[dimethyl(aminoethyl)] methacrylate – block – polystyrene (PDMAEMA-b-PS). A distinct PDMAEMA block, a thermo and pH-responsive polymer, was used for each series. Aliquots removed during PS block polymerization at various times provided copolymers with increasing hydrophobic content. Materials were fully characterized and had their aggregation state (DLS) and cloud point determined in aqueous media, providing information on the effects of polarity and aggregation state on the cloud point.
Results show a tendency to a drop in the cloud point values as the PS content increases, as expected. However, an abrupt break in this trend is observed as the system undergoes an aggregation transition due to higher hydrophobic/hydrophilic ratios of the copolymer, indicating that aggregation affects the system's thermal behavior due to the isolation of the hydrophobic block in the core of the aggregates and/or by changing the pH in the aggregate´s hydrophilic corona. Therefore, the thermal behavior in the aqueous media of PDMAEMA-b-PS copolymers depends not only on the average polarity of the copolymer but also on the aggregation state (free chains or micelles, for example).

Traditional polymers provide durability and structural integrity, but often lack adaptability. In contrast, supramolecular polymers rely on non-covalent interactions, enabling dynamic and reversible behavior. While these polymers offer enhanced responsiveness, they may sacrifice mechanical strength. Supramolecular microcrystals bridge this gap by combining the rigidity of crystalline structures with the adaptive nature of supramolecular assemblies, offering promising applications in catalysis, optoelectronics, and stimuli-responsive materials.

In this work, we show how the use of photochromic spiropyran as monomer enables the formation of supramolecular light-responsive microcrystals and microcrystalline structures. We studied how small modifications in the monomer’s design, have an impact the final material morphology, nanostructure, and light responsiveness. Previous reports[1-2] described how photoisomerization of these molecules is hindered in crystalline materials, but with our design, we show that the monomers not only still respond to light in the self-assembled microcrystals, but also allow them to undergo morphological transitions upon irradiation. Moreover, we extensively studied the nanostructure of the self-assembled microcrystals using x-ray scattering techniques and a combination of optical, electronic and force microscopy. We used the acquired knowledge to set the rules for the rational design of light-responsive microcrystalline structures.

Finally, we were able to turn the self-assembly active monomers into water-soluble units, capable of light-triggered dissipative self-assembly. In this way, we were able to create dynamic microcrystalline materials capable of self-assembly outside of the thermodynamic minima, i.e. capable of mimicking biological self-assembly. This work represents the first example of single-component light-activated out-of-equilibrium microcrystalline structures.

Compartmentalization plays a crucial role in developing complex chemical systems, where numerous chemical reactions interact to produce emergent behaviours.¹ These compartments need to be dynamic and operate out of equilibrium. Complex coacervates, liquid droplets formed via electrostatic interactions between polyelectrolytes, serve as versatile compartments due to their ability to form, dissolve, and regulate solute interactions in response to ionic strength.² ³However, their primary limitation is their equilibrium nature, preventing time-dependent behaviours such as aging. Efforts to drive coacervates out of equilibrium often rely on chemical fuels specific to certain polyelectrolyte systems.⁴
Recently, our group demonstrated the timed formation and aging of coacervates using ammonium carbonate, an unstable salt that decomposes into volatile species, lowers ionic strength, and induces coacervate formation.⁵ This approach is broadly applicable as it modulates solution conditions rather than the coacervates themselves. Here, we explore the reverse process using enzyme-catalyzed urea decomposition to regenerate ammonium and carbonate ions, increase ionic strength, and dissolve coacervates. This cycle enables repeated coacervate formation and dissolution without waste accumulation.
Furthermore, the combination of salt formation and decomposition can be used to maintain our system out of equilibrium, potentially leading to other emergent behaviours such as transient formation or dissolution of coacervates with tunable lifetimes. Finally, the change in the coacervate properties can potentially be used to regulate the reaction kinetics or self-assembly.

Synthetic membranes are ubiquitous, and their application is crucial to strategic sectors such as health, water purification and industrial production. Improving the separation performance of synthetic membranes is a critical priority but it represents a big challenge due to the existence of a trade-off between permeability (speed of separation) and selectivity (precision of separation). Biological membranes, display both high selectivity and permeability. The barrier function of biotic membranes is provided by a self-assembled phospholipid bilayer that is virtually impermeable for hydrophilic and charged molecules. Extreme selectivity is achieved through proteins embedded in the bilayer, which operate as selective transport units. Additionally, unlike their synthetic counterpart, biological membranes are dynamic and self-healing because they are held together by reversible supramolecular interactions.
Block copolymers have been used successfully to reconstitute natural membrane proteins for their ability to form bilayers akin to the cell wall. Unfortunately, these biomimetic membranes display a lack of scalability which hinders their application in separation processes. In this talk we present a self-assembly strategy to scale block copolymer bilayers up to the macroscopic scale, unlocking their technological potential in separation science. We use the interface between two immiscible aqueous solutions to template and stabilize the formation block copolymer bilayers with thickness of approximately 30 nm and surface areas exceeding 10 cm2. The method enables the incorporation of biological transporters and yields functional membranes that display ion-selective and self-healing properties. These membranes can be also incorporated into devices and used, for example, to convert ion gradients into electricity.

The need for more sustainable polymeric materials has intensified research efforts into recyclable and reprocessable cross-linked systems. Cross-linked polyurethanes (PUs) are widely used due to their outstanding mechanical properties and chemical resistance, yet their permanent network structure presents significant challenges for end-of-life management. Incorporating dynamic covalent bonds into polyurethane networks offers a promising approach to overcoming these limitations by enabling thermal reversibility and material reprocessing.

This study explores the implementation of thermally reversible cross-links based on Diels-Alder (DA) chemistry to improve the recyclability of cross-linked PUs. The synthesis and incorporation of dynamic cross-linkers, together with the influence of molecular design and cross-linker purity, are analyzed to assess their impact on thermal and mechanical properties. The reversibility of the network structure is investigated through differential scanning calorimetry, rheological measurements, and stress-relaxation analysis, demonstrating efficient reprocessing capabilities. The ability to recover mechanical performance after recycling highlights the potential of dynamic covalent networks to extend the lifespan of cross-linked PUs. However, side reactions such as maleimide homo-polymerization are also considered, as they may impact long-term reusability.

The results reinforce the viability of integrating reprocessable architectures into cross-linked PUs as a pathway toward more sustainable material solutions. By combining bio-based components with dynamic cross-linking strategies, new opportunities arise for reducing polymer waste and advancing sustainability and circular economy principles in high-performance polyurethane applications.