Double network hydrogels (DNH) are a specific form of interpenetrating polymer networks that outperform all existing hydrogels in terms of mechanical strength. One of many application possibilities of such networks is the substitution of cartilage, which has the Youngs Modulus of rubber and the compression strength of concrete.
Here, we report on a novel ultrastrong double-network hydrogel based on poly(2-methyl-2-oxazoline) and poly(acrylic acid), which is stabilized by hydrogen bonds between the polymers involved; even at physiological pH conditions above the pKa (4.7) of acrylic acid. The resulting biocompatible, non-cytotoxic material exhibits not only remarkably high compressive strength of up to 60 MPa, but also shows a compressive modulus, water content, friction coefficient, and a dynamic load behavior similar to the challenging cartilage. Variation of poly(2-oxazoline)s and acrylates reveal that polymer structures, distances in the hydrogel and the nature of the hydrogen donors play an important role in achieving such a mechanical performance. An additional feature is to exchange a minor amount of functional groups of 5 to 10 mol% in the poly(acrylate) network, which has a tremendous effect on toughness and even on resistance against deprotonation. Thus, poly(2-oxazoline)-based double network hydrogels are a platform of exceptionally strong and tough hydrogels with adjustable properties.

We investigate the toughening of epoxies with layered poly(ether imide) (PEI) structures at the meso- to macroscale. This is further combined with gradient morphologies at the microscale originating from reaction-induced phase separation. Characteristic micro-scale features of the gradient morphology were controlled by the curing temperature, while the layered macro structure originates from facile scaffold manufacturing techniques with varying poly(ether imide) layer thicknesses. The fracture toughness of the heterogeneous system is investigated as a function of varying cure temperature (120–200 °C) and PEI film thickness (50–120 μm). Interestingly, the result shows that the fracture toughness was mainly controlled by the macroscopic feature, being the final PEI layer thickness, i.e., film thickness remaining after partial dissolution and curing. Remarkably, as the PEI layer thickness exceeds the plastic zone around the crack tip, around 62 μm, the fracture toughness of the dual scale morphology exceeds the property of bulk PEI in addition to a 3-fold increase in the toughness of pure epoxy. On the other hand, when the final PEI thickness was smaller than its plastic zone, the fracture toughness of the architected system was lower than pure PEI but still higher than pure epoxy (1.5–2 times) and “bulk toughened” system with the same volume percentage. This indicates the governing mechanism relating to microscale interphase morphology. Interestingly, decreasing the gradient microscale interphase morphology can be used to trigger an alternative failure mode with a higher crack tortuosity, which seems to be the dominating synergistic toughening effect.

Nowadays, the main interest of many research groups is focused on development and characterization of multifunctional nanocomposite materials based on nanostructured polymeric matrices. Intensive progress in Materials Science required advanced techniques, which allow to investigate the properties of developed nanocomposite materials at the nanoscale. This is directly related to the wide range of applications of these materials in different sectors such as constructions, aeronautics, electronics, medicine, pharmaceutics, cosmetics and others.

Atomic force microscopy (AFM) is one of the widely used techniques to study the topography and morphology of different nanocomposite materials. As is well known these techniques allow also to measure electric conductivity in both quantitative way using tunneling atomic force microscopy (TUNA)) or qualitative way using electrostatic force microscopy (EFM). Moreover, the progressive development of this technique, in the last decade, enables quantitative measurement of nanomechanical properties. This novel technology called PeakForce quantitative nanomechanical mapping (PeakForce QNM) detects simultaneously the topography, elastic modulus and adhesion of investigated materials.

In present work, different kinds of nanostructured polymer materials (block copolymers and thermosets) and their nanocomposites were successfully analyzed using EFM, TUNA or PeakForce QNM techniques. The main aim of this investigation was focused on better understanding of the relationship between electric conductivity or mechanical properties and morphology of designed materials at the nanoscale level.

Acknowledgement:
Financial support from MCIN/AEI/10.13039/501100011033 and FEDER in the frame of PID2021-126417NB-I00 project is gratefully acknowledged.

New composite materials were obtained by modifying cotton fabric with chitosan or modified chitosan with benzaldehyde, and both polymers crosslinked with glutaraldehyde. ZnO particles, synthesized in situ, were included in the polymer films. Chitosan's ability to coordinate with zinc ions was used to prepare inorganic particles with a determined size, structure, and distribution in the polymer layer. The presence of hydrophilic or hydrophobic functional groups in the chitosan chain affected the morphology of the organic film and inorganic particles.
Optical and scanning electron microscopies revealed that a uniform chitosan layer was formed on the cotton fabric, which slows the thermal degradation of the materials and prevents them from complete weight loss, as the untreated cotton fabric. Including ZnO particles in the film leads to a denser coating with typical roughness and porosity, characterized by the Brunauer Emmett Teller (BET) method and atomic force microscope (AFM). Energy Dispersive X-ray (EDX) analysis and mapping for the Zn element show that zinc is homogeneously distributed on the fabric surface.
The obtained materials have been investigated in vitro against model microbial strains: Gram-positive and Gram-negative bacteria, fungi and viruses.
Their ability to wipe spills from crude oil and oil products in water has many advantages. They are flexible and stable, float on the water, and can be regenerated and used repeatedly.


Acknowledgements: The authors gratefully acknowledge the financial support by the European Union-NextGenerationEU through the National Recovery and Resilience Plan of the Republic of Bulgaria, project № BG-RRP-2.004-0002, „BiOrgaMCT”.

Block copolymers (BCPs) consisted of two or more distinct physicochemical properties can self-assemble into abundant morphologies.[1] Conferring percolating pore structures to the self-assembled BCPs has received tremendous attention in advanced membrane separation in decades.[2, 3] With the flourishment of sustainable materials in recent years, it necessitates to develop sustainable BCPs in membrane manufacturing for environmental mitigation. To this end, we synthesized the environmental friendly sustainable BCPs, the polycarbonate-based triblock copolymers with the carboxyl-terminated homopolymer sides.[4] Then the BCPs were treated by the developed pore-forming strategy for seconds at room temperature. In this way, the nanoporous BCP membranes with the pore walls functionalized by the carboxyl-terminated homopolymer sides were prepared. Such membranes were able to reject 94.2% brilliant blue R (826 g/mol) by virtue of electrostatic repulsion between the membrane pore walls and the dye molecules. Meanwhile, the water permeance was maintained as around 1020 L/(m2·h·bar), which is 1-3 orders of magnitude higher than that of other membranes with the similar rejections.
Taking advantage of the highly tuned pore sizes, the BCP membranes were further served as the porous substrates for constructing catalytic membranes.[5] The membranes confined the degradation reactions within the nanopores in such a way that the generated radicals during filtration could rapidly degrade dyes. A series of pollutants (e.g., methylene blue, brilliant blue, tetracycline) were almost completely removed from water by the membranes while the permeance was up to 1866 L/(m2·h·bar). These works unfold a seductive opportunity for BCP membranes in highly efficient remediation of wastewater.

Due to their exceptional corona structure, patch-like surface-compartmentalized micelles (patchy micelles) are highly interesting for relevant applications, e.g. as efficient stabilizers for emulsions or compatibilizers for polymer blends. One elegant way to produce worm-like patchy micelles is crystallization-driven self-assembly of triblock terpolymers with a crystallizable middle block [1]. However, other geometries like spherical or disc-shaped patchy micelles are only rarely reported. Here, we present stereocomplex-driven self-assembly (SCDSA) as a facile route to spherical patchy micelles with a semicrystalline stereocomplex (SC) core in organic solvents, employing diblock copolymers with enantiomeric poly(L-lactide)/poly(D-Lactide) blocks and highly incompatible corona-forming blocks (polystyrene (PS), poly(tert-butyl methacrylate) (PtBMA)) [2]. Theses micelles are efficient compatibilizers for highly immiscible PS/PtBMA blends as they improve the homogeneity of the blend and significantly reduce the PS droplet size [3]. This is attributed to their adaptive corona structure, resulting in a selective swelling/collapse of the respective miscible/immiscible corona patches at the blend interface. The incorporation of a fluorescent dye inside the SC micelle core via SCDSA allows the use of confocal scanning fluorescence microscopy to localize the patchy SC micelles, being predominantly assembled at the PS/PtBMA blend interface.