Roberto Lazzaroni

Chiral induction by the solvent phase offers a promising route to achieve homochirality in self-assembled molecular networks. In this work, we examine solvent-driven chiral induction at the solid–liquid interface, where an enantiopure solvent biases the handedness of two-dimensional (2D) networks formed by achiral molecules physisorbed on the basal plane of highly oriented pyrolytic graphite. Using scanning tunneling microscopy at the liquid–solid interface, we visualize the 2D organization of the achiral monomer 10,12-pentacosadiynoic acid in chiral liquid environments. We compare the induction efficiencies of several enantiopure citronellyl-derived solvents that differ in their capacities for specific solute–solvent interactions. Complementary molecular dynamics simulations provide molecular-level insight into the possible mechanisms of solvent-mediated chiral induction.

Weak dipole–dipole interactions drive the formation of 2D honeycomb porous networks at interfaces. STM and simulations uncover how subtle molecular design and interfacial forces control stability, switching behavior, and guest inclusion.

Combining surface chirality and photoresponsiveness can result in interfaces with dynamic stereochemical properties. Such materials offer unique opportunities in the context of tunable chiral recognition at interfaces. Here, we present a strategy to achieve dynamically chiral surfaces using self-assembled molecular networks (SAMNs) of overcrowded alkene-based molecular motors on highly oriented pyrolytic graphite. The chiroptical properties and the dynamic behavior of the molecular motors are maintained when confined in the SAMN, as shown using scanning tunneling microscopy (STM) with in situ irradiation. Light triggers the transition from a homochiral assembly of the stable state of a molecular motor (RP chirality) to the heterochiral coassembly between the stable and the metastable state (RP/RM chirality). The RP/RM coassembly is a kinetic phase that disappears once the external stimulus is removed─highlighting the reversibility of the system. These results demonstrate how molecular motion can be harnessed to encode reversible chirality into surfaces.

Combining surface chirality and photo-responsiveness can result in interfaces with dynamic stereochemical properties. Such materials offer unique opportunities in the context of tunable chiral recognition at interfaces. Here, we present a strategy to achieve dynamically chiral surfaces using self-assembled molecular networks (SAMNs) of overcrowded alkene-based molecular motors on highly oriented pyrolytic graphite. The chiroptical properties and the dynamic behaviour of the molecular motors are maintained when confined in the SAMN, as shown using scanning tunneling microscopy (STM) with in-situ irradiation. Light triggers the transition from a homochiral assembly of the stable state of a molecular motor (RP chirality) to the heterochiral co-assembly between the stable and the metastable state (RP/RM chirality). The RP/RM co-assembly is a kinetic phase that disappears once the external stimulus is removed – highlighting the reversibility of the system. These results demonstrate how molecular motion can be harnessed to encode reversible chirality into surfaces.

Porous materials have evolved from rigid, strongly bonded inorganic materials, such as zeolites, to modular and adaptable metal-organic and covalent organic frameworks (MOFs and COFs), based on reversible intermolecular interactions. The shift towards weak and reversible interactions continues, where recent research has explored porous materials based on even weaker interactions, such as hydrogen bonding and electrostatic forces. Building on this trend, here we report the formation of two-dimensional (2D) honeycomb porous supramolecular networks driven by weak, yet directional dipole-dipole interactions formed at the solution-solid interface. Scanning tunneling microscopy (STM) and molecular modeling reveal how these interactions guide self-assembly and structural stability. A comparative investigation of a structurally similar building block highlights the role of molecular design and interfacial forces in tuning these interactions. Molecular mechanics and molecular dynamics (MM and MD) simulations were conducted to understand the stabilization of experimentally observed supramolecular networks, considering the roles of molecule-substrate and molecule-solvent interactions. We further report on electric field-mediated switching behavior within these networks and their ability to host suitable guest molecules. This study highlights the increasing importance of weak intermolecular forces in the design of porous materials, paving the way for dynamic and reconfigurable nanomaterials.

Copolymerization allows tuning polymer’s properties and a synergetic effect may be achieved for the resulting hybrid, i.e., outperforming the properties of its parents as often observed in natural materials. This synergetic concept is herein applied to enhance both dynamicity and properties of vitrimeric materials using poorly dynamic hydroxyurethane and non-dynamic epoxy thermosets. The latter generates activated hydroxyl, promoting exchange reactions 15 times faster than pure polyhydroxyurethanes. This strategy allows obtaining catalyst-free high-performance vitrimers from conventional epoxy-amine formulations and an easily scalable (bio-)CO2-based yet poorly efficient dynamic network. The resulting hybrid network exhibits modulus retention superior to 95% with fast relaxation (<10 min). The hydroxyurethane moieties actively participate in the network to enhance the properties of the hybrid. The material can be manufactured as any conventional epoxy formulation. This new strategy to design dynamic networks opens the door to large-scale circular high-performance structural carbon fiber composites (CFRP). The CFRP can be easily reshaped and welded from flat plates to complex geometries. The network is degradable under mild conditions, facilitating the recovery and re-use of high-added-value fibers. This accessible and cost-effective approach provides a versatile range of tunable dynamic epoxides, applicable across various industries with minimal adjustments to existing marketed products.

We herein propose capitalizing on strong hydrogen bonding from novel bio-CO2-derived dynamic thermosets to achieve high-performance natural fiber composites (NFC) with circular features. CO2- and biomass-derived polyhydroxyurethane (PHU) thermosets were selected, for the first time of our knowledge, as matrices for their ability to make strong H-bond, resulting in outstanding mechanical properties for NFC. Exploiting this H-bond key feature, exceptional interface bonding between flax and PHU was confirmed by atomic force microscopy and rationalized by atomistic simulation. Without any treatment, an increase of 30% of stiffness and strength was unveiled compared to an epoxy benchmark, reaching 35 GPa and 440 MPa respectively. Related to the thermoreversible nature of hydroxyurethane moieties, cured flax-PHU were successfully self-welded and displayed promising properties, together with recyclability features. This opens advanced opportunities that cannot be reached with epoxy-based composites. Implementing CO2-derived thermosets in NFC could lead to more circular materials, critical for achieving sustainability goals.

Shapeable and flexible pressure sensors with superior mechanical and electrical properties are of major interest as they can be employed in a wide range of applications. In this regard, elastomer‐based composites incorporating carbon nanomaterials in the insulating matrix embody an appealing solution for designing flexible pressure sensors with specific properties. In this study, PDMS chains of different molecular weight were successfully functionalized with benzoxazine moieties in order to thermally cure them without adding a second component, nor a catalyst or an initiator. These precursors were then blended with 1 weight percent of multi‐walled carbon nanotubes (CNTs) using an ultrasound probe, which induced a transition from a liquid‐like to a gel‐like behavior as CNTs generate an interconnected network within the matrix. After curing, the resulting nanocomposites exhibit mechanical and electrical properties making them highly promising materials for pressure‐sensing applications.