Novel hydrogels containing Nafion and poly(ethylene oxide) based block copolymers

Antimicrobial coatings based on amine-terminated graphene oxide and Nafion with remarkable thermal resistance

We present a novel type of layer-by-layer (LbL) waterborne coating based on Nafion and amine-terminated graphene oxide (GO-NH2) that inhibits the growth of Escherichia coli and Staphylococcus aureus by more than 99% and this performance is not compromised upon extensive thermal annealing at 200 °C. Quartz crystal microbalance (QCM) sensorgrams allow the real time monitoring of the build-up of the LbL assemblies, a process that relies on the strong electrostatic interactions between Nafion (pH = 2.7, ζ = -54.8 mV) and GO-NH2 (pH = 2, ζ = 26.7 mV). Atomic force microscopy (AFM), contact angle and zeta potential measurements were used to characterise the multilayer assemblies. We demonstrate here that Nafion/GO-NH2 advanced coatings can offer drug-free and long-lasting solutions to microbial colonization and can withstand dry heat sterilization, without any decline in their performance.

Layer by Layer Antimicrobial Coatings Based on Nafion, Lysozyme, and Chitosan

The study focuses on the development of a new family of layer-by-layer coatings comprising Nafion, lysozyme and chitosan to address challenges related to microbial contamination. Circular dichroism was employed to gain insights on the interactions of the building blocks at the molecular level. Quartz crystal microbalance tests were used to monitor in real time the build-up of multilayer coatings, while atomic force microscopy, contact angle and surface zeta potential measurements were performed to assess the surface characteristics of the multilayer assemblies. Remarkably, the nanocoated surfaces show almost 100% reduction in the population of both Escherichia coli and Staphylococcus aureus. The study suggests that Nafion based synergistic platforms can offer an effective line of defence against bacteria, facilitating antimicrobial mechanisms that go beyond the concept of exclusion zone.

Characterization of Sodium and Potassium Nitrate Contaminated Polyaniline-Poly (Ethylene Oxide) Composites Synthesized via Facile Solution Casting Technique

Fabrication of composites by developing simple techniques can be an effective way to modify some properties of individual materials. The present study relates to facile synthesis of sodium nitrate (NaNO₃) and potassium nitrate (KNO₃) contaminated polyaniline (PANI) and poly (ethylene oxide) (PEO) composites without using any additives, plasticizers, or fibers. The physic-chemical and rheological properties of synthesized composites were analyzed. The composites showed enhancement in both storage and loss modules in comparison with the polymer matrices. The dynamic viscosity of the synthesized materials has inverse relation with that of temperature and shear stress. Rheological analysis reveals a continuous drop off in viscosity by increasing shear stress. The flow behavior was affected little by temperature. However, the overall results showed a shear thinning effect suggesting that polymer composites show non-Newtonian behavior. The addition of NaNO₃ and KNO₃ had a profound effect on shear viscosity of the materials, although the overall shear thinning behavior prevails. The PANI-PEO composite follows, as the first approximation models, both Bingham and modified Bingham models, while the salt contaminated system follows only the Bingham model. Both show shear stress values. The greater values of storage (G′) and loss (G″) modulus of composites than PANI-PEO blend suggests excellent elasticity, better stiffness, and good mechanical strength of the composites. Furthermore, the composites were more thermally stable than pure polymers.