Undisputedly, multicomponent polymer architectures have gained significant interest over the years due to their special properties and to the large variety of application possibilities. Among such macromolecular materials, polymer conetworks, especially amphiphilic conetworks (APCNs), composed of chemically (covalently) bonded hydrophilic and hydrophobic polymer chains, belong to a special class of rapidly emerging nanostructured materials with various unique structural features and characteristics (see e.g. Refs. 1-5). Because of the immiscibility of the components, the synthesis of such macromolecular assemblies is quite challenging. Several successful synthetic routes have recently been developed by us, including various protection-deprotection schemes. Unique bicontinuous (cocontinuous) nanophase separated morphology exists in APCNs in a broad composition window with domain sizes in the range of ~2-30 nm. This provides unprecedented possibilities to obtain various new specialty intelligent (smart, responsive) and organic solvent selective superabsorbent poly(ionic liquid) conetwork gels, and catalytically active organic-inorganic nanohybrids by applying one of the nanophases as nanoreactor. The resulting novel materials have a variety of high value-added potential applications from intelligent drug delivery to antibacterial biomaterials, nanocatalysis, photonics, energy and environment protection related materials, sensors, and specialty superabsorbents etc.


Acknowledgements. Support by the National Research, Development and Innovation Office, Hungary (NN116252, NN129366, K135946, PD139162) and the European Research Area ERA-Chemistry program is acknowledged.

Polyelectrolyte’s complexation is a versatile tool that can be used for the preparation of functional composites or coatings due to the wide range of polyelectrolyte combinations and assembly parameters. Here, polyelectrolytes complexes (PECs) are employed as an efficient tool for the preparation of 3D self-standing natural polymer-based composites with flame retardant characteristics. Chitosan and sodium polyphosphate PECs were deposited in a layer-by-layer (LbL) fashion on cellulose fibers producing lightweight fiber-networks by a freeze-drying approach [1]. SEM micrographs demonstrated the coating acted as a glue enabling the production of a 3D porous structure with a content of cellulose fibers ranging from 80 to 90% wt. The 3 layers of chitosan/polyphosphate pair deposition prevented the flame spread after direct flame application in horizontal and vertical configuration. By cone calorimetry, the foams showed a total smoke release one order of magnitude lower than commercial polyurethane foams and extremely limited heat release rates. In a circular economy perspective, LbL-treated rice husk particles, collected as waste from food industry were combined with cellulose nanofibrils for the production of lightweight composites (density 40-80 kg/m3) characterized by 80%wt rice husk content. The samples showed self-extinguishing behavior in both horizontal and vertical configuration flammability tests. Similarly, aiming at a completely renewable composition, grape pomace particles were mixed with cellulose nanocrystals/gelatin PECs producing porous easily handle lightweight composites (density of 80 kg/m3) with freeze-drying procedure. These results clearly show the potentialities of PECs as viable tool enabling the production of sustainable lightweight materials capable of competing with petroleum-based foams.

Shape-morphing hydrogels (SMHs) are often bilayers (Fig. 1-A) consisting of an active layer, whose swelling capacity changes in response to a stimulus, and a passive layer, which exhibits a constant swelling degree [1]. This swelling differential causes a deformation of the material. It is thus relatively simple to design SMHs that respond to one stimulus. For instance, poly(N-isopropylacrylamide) in the active layer yields a thermosensitive SMH [2]. However, it is still challenging to design SMHs combining a simple composition and a response to several stimuli.
To overcome this issue, we propose to include stimuli-responsive supramolecular complexes into the active layer of an SMH. For that, naphthalene moieties were grafted in the upper layer of a poly(ethylene glycol) (PEG)-based hydrogel bilayer (Fig. 1-A(i)). Upon immersion into a solution containing hydrophilic electro-deficient cyclobis(paraquat-p-phenylene) (Blue Box), swelling and color changes of the active layer were obtained due to the formation of tetracationic based complexes (Fig.1-A(ii)) [3]. We then investigated the effect of different environmental cues (dilution, temperature, RedOx) on the expansion (α) of each layer and the subsequent deformation of the bilayer system (Fig. 1-B). We showed that these stimuli could be employed to efficiently control the degree of bending of the bilayer thanks to the synergy between the intrinsic properties of the PEG network and the dissociation/association of the supramolecular complexes. Building on this knowledge, we fabricated SMHs with attractive architectures and functions (Fig. 1-C).

Mechanical metamaterials – geometrically architected materials with unusual properties – show widespread promise from origami-type folding to vibration-dampening properties in high performance materials. Metamaterials with multiple stable states, an important subclass of metamaterials in general, are notable because each state may be used for different functions in the same material. Interestingly, such metamaterials often show solitons, that is propagation of waves of activation, as the materials switch between states. So far, these studies have mostly remained in the realm of mechanical engineering, yet incorporating chemical ‘solitons’ may open up new perspectives in actively driving such material changes with chemical reactions. As such, soft polymeric metamaterials incorporating chemical reaction cascades may enable new, adaptive folding responses through locally patterning signal distribution. In this context, we study how autocatalytic waves propagate across metamaterials fabricated from double network hydrogels. We show how the folding state of the mechanical metamaterial shapes signal propagation across a range of material geometries and how folding can influence distribution of signals. In particular, we show that folding state can influence whether chemical signals propagate via hinges or via folding contact points. This programmable signal propagation across architected materials opens up new avenues for controllable material folding in active metamaterials.

Robots have reshaped manufacturing, yet their usefulness for applications beyond industry, in e.g. disaster relief, (health)care, and prostheses/exoskeletons demands new approaches to programming deformations in soft and hybrid bodies.[1] Programming motion in synthetic materials through stimuli other than electricity such as chemical and/or physical triggers remains challenging, with current methods to be largely limited to single and/or material-specific deformations can be chemically programmed.[2]
To enhance the versatility of soft robotic materials, we introduce a novel liquid-crystalline side-chain end-on architecture capable of exhibiting opposite deformation modes in response to external stimuli, rooted in multiple phase-transitions.[3] Liquid crystalline elastomers (LCEs) offer a range of stimuli-driven deformations, where the molecularly controllable self assembly of the mesogens dictates ordered phases, allowing for multiple predictable directions of macroscopic deformations within a single material.[4] We further show that fine tuning of the polymeric chain elasticity and the stresses induced upon the UV-polymerization of magnetically aligned monomers can lead to the formation of two high-ordered phases, namely chevron Smectic C and Smectic A. This unanticipated reversible behavior are scalable, broadening the toolbox for rationally designing multimodal, single-material soft actuators.

Hydrogels are three-dimensional polymer networks with high water content, making them ideal for soft actuators. They can achieve up to 70% volume change in response to stimuli, with programmable actuation modes and mild activation conditions [1].
A major challenge for hydrogel actuators is their slow actuation due to diffusion-limited water transport. Strategies like phase separation, 3D printing, pore-forming agents, freeze-drying, gas bubble generation, and electrospinning [2] have created porous hydrogels with response times of 1 second [3,4]. However, these methods often weaken mechanical properties, such as modulus, toughness, and tensile strength. A design concept that achieves ultra-fast actuation while enhancing these properties is still needed.
In this work, we rationally designed a hydrogel actuator with metal coordination complexes and crystallizable components. The resulting crystalline hydrogel actuators exhibited 33 times higher tensile strength, 22 times higher Young's modulus, and 20 times higher toughness than non-crystalline hydrogels. Additionally, our method created a highly porous structure through phase separation. We demonstrate that even for large-sized cylindrical hydrogels (radius = 9 mm, height = 25 mm), the response time was only 76s from the fully swollen state to the fully collapsed state when heated above LCST, which is much faster than the previous non-porous cylinder hydrogel samples with radius of 2.25 mm (response time ≥ 10 mins) [5].