Two-Layer Functional Coatings of Chitosan Particles with Embedded Catechin and Pomegranate Extracts for Potential Active Packaging

Two-layer functional coatings for polyethylene (PE) and polypropylene (PP) films were developed for the active packaging concept. Prior to coating, the polymer films were activated by O2 and NH3 plasma to increase their surface free energy and to improve the binding capacity and stability of the coatings. The first layer was prepared from a macromolecular chitosan solution, while the second (upper) layer contained chitosan particles with embedded catechin or pomegranate extract. Functionalized films were analyzed physico-chemically to elemental composition using ATR-FTIR spectroscopy and XPS. Further, oxygen permeability and wettability (Contact Angle) were examined. The antimicrobial properties were analyzed by the standard ISO 22196 method, while the antioxidative properties were determined with an ABTS assay. Functionalized films show excellent antioxidative and antimicrobial efficacy. A huge decrease in oxygen permeability was achieved in addition. Moreover, a desorption experiment was also performed, confirming that the migration profile of a compound from the surfaces was in accordance with the required overall migration limit. All these properties indicate the great potential of the developed active films/foils for end-uses in food packaging.

Edible and Functionalized Films/Coatings—Performances and Perspectives

In recent years, food packaging has evolved from an inert and polluting waste that remains after using the product toward an active item that can be consumed along with the food it contains. Edible films and coatings represent a healthy alternative to classic food packaging. Therefore, a significant number of studies have focused on the development of biodegradable enveloping materials based on biopolymers. Animal and vegetal proteins, starch, and chitosan from different sources have been used to prepare adequate packaging for perishable food. Moreover, these edible layers have the ability to carry different active substances such as essential oils—plant extracts containing polyphenols—which bring them considerable antioxidant and antimicrobial activity. This review presents the latest updates on the use of edible films/coatings with different compositions with a focus on natural compounds from plants, and it also includes an assessment of their mechanical and physicochemical features. The plant compounds are essential in many cases for considerable improvement of the organoleptic qualities of embedded food, since they protect the food from different aggressive pathogens. Moreover, some of these useful compounds can be extracted from waste such as pomace, peels etc., which contributes to the sustainable development of this industry.

Synthesis of polyhydroxyurethanes from di(trimethylolpropane) and their application to quaternary ammonium chloride-functionalized films

Polyhydroxyurethanes synthesized using non-isocyanate and non-phosgene derivatives afford quaternary ammonium chloride (QAC)-functionalized films after chloroacetylation and quaternization with cross-linkable amines.

Synthesis of Hydrophilic Epoxy-Functionalized Films by UV-Initiated Copolymerization

Bisphenol A based epoxy acrylate (BABEA), a commercial ultraviolet (UV)-curiable material, was introduced as a new manufacturing material for facile fabrication of epoxy-functionalized films through UV-initiated copolymerization using glycidyl methacrylate (GMA) as the functional monomer. X-ray photoelectron spectroscope (XPS) results indicated the existence of epoxy groups on the surface of the poly (BABEA-co-GMA), which allowed for binding protein through an epoxy-amino group reaction. The contact angel results indicated the poly (BABEA-co-MMA) is hydrophilic, which avoided nonspecific adsorption of biological species. Bovine serum albumin (BSA) was successfully immobilized on the poly (BABEA-co-GMA) films by using the introduced epoxy groups effectively. This makes it possible to extend the application of such films in the fields of bio-separations and bio-recognitions.

ACTIVATION AND DEACTIVATION OF ROOM TEMPERATURE FERROMAGNETISM IN ZnO FILMS

In this paper, we report the activation and deactivation of room temperature ferromagnetism in pure and V doped ZnO ( Zn0.95V0.05O ) films upon surface functionalization with thiol. The thiol functionalized pure ZnO and Zn0.95V0.05O films has been investigated with X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), temperature programmed desorption (TPD) and vibrating sample magnetometer (VSM) measurements. The presence of S 2p3/2 peak about 163.5 eV implies that the formation of Zn-S bonds which in turn leads to the reduction of oxygen vacancies. PL spectra of thiol functionalized pure ZnO and Zn0.95V0.05O films show quenching of visible emission in comparison with the unfunctionalized ZnO films. TPD measurements show that the adsorption of thiol on ZnO surface is stable upto 480 K. On vacuum annealing of the thiol functionalized films above 480 K, desorption starts and gets completely desorbed about 535 K. The room temperature VSM measurements reveal clear signature of ferromagnetic behavior in the functionalized ZnO films. The disappearance of ferromagnetic behavior after vacuum annealing at 550 K confirms the observed ferromagnetic behavior in thiol functionalized ZnO films is due to the strong interaction between the ZnO host and thiol molecules.