Surface Functionalization of Face Masks with Cold Plasma and Its Effect in Anchoring Polyphenols Extracted from Agri-Food

Abstract

To improve the capability of non-woven polypropylene-based fabric (NWF-PP) used for face mask production to retain active biomolecules such as polyphenols, the surface functionalization of NWF-PP–directly cut from face masks–was carried out by employing cold plasma with oxygen. The nature/structure of the functional groups, as well as the degree of functionalization, were evaluated by ATR-FTIR and XPS by varying the experimental conditions (generator power, treatment time, and oxygen flow). The effects of plasma activation on mechanical and morphological characteristics were evaluated by stress–strain measurements and SEM analysis. The ability of functionalized NWF-PP to firmly anchor polyphenols extracted from cloves was estimated by ATR-FTIR analysis, IR imaging, extractions in physiological solution, and OIT analysis (before and after extraction), as well as by SEM analysis. All the results obtained converge in showing that, although the plasma treatment causes changes–not only on the surface–with certain detriment to the mechanical performance of the NWF-PP, the incorporated functionalities are able to retain/anchor the active molecules extracted from the cloves, thus stabilizing the treated surfaces against thermo-oxidation even after prolonged extraction.

Coating of Polypropylene Non‐Woven Fabric with Layered Double Hydroxides Bearing Antioxidant and Antibacterial Natural Compounds

“…A new band envelope in the region between 1800 and 1500 cm −1 with a maximum at 1715 cm −1 was observed, which can be attributed to the presence of oxidized species formed on the PP surface due to plasma treatment. [ 24 ] By performing a deconvolution procedure in the range 1850–1500 cm −1 (Figure 5b), four main contributions to the envelope were identified [ 24 ] : the band at 1740 cm −1 associated with C≐O stretching of peroxyacid, carboxylic acid monomer and possibly esters (also unsaturated), the band at 1710 cm −1 due to C═O stretching of carboxylic acid dimer or aldehydes, ketones, and possibly esters, the band at about 1647 cm −1 due to unsaturated carbonyls (both aldehydes and ketones) and vinyl double bonds, and the band at about 1590 cm −1 probably due to the bending of ‐NH and ‐NH 2 groups generated by the reaction of carbon radicals with nitrogen when the treated samples are exposed to air.…”

“…This test measures the sample's resistance to thermally induced oxidation by determining the time required for exothermic oxidation during an isothermal experiment performed under oxygen flow. [16,24,57] The results gathered in Table 3 showed that NWF is oxidized at 180 °C in less than 2 min after introducing oxygen into the DSC chamber. Furthermore, the plasma treatment led to the production of oxidized species on the surface, which accelerated the degradation processes at high temperatures, reducing the substrate's OIT to less than 1 minute.…”

“…[ 22 ],[ 23 ] Our group has recently demonstrated that plasma treatment of PP NWF can enhance the immobilization of natural extracts on the activated surface of NWF. [ 24 ]…”

“…[22], [23] Our group has recently demonstrated that plasma treatment of PP NWF can enhance the immobilization of natural extracts on the activated surface of NWF. [24] Polydopamine (pDA) is a biologically inspired polymer with strong adhesive properties, and it can adhere to many substrates, including PP-based surfaces. PDA is produced in situ by dopamine oxidative self-polymerization in buffered water, without damaging the surface and giving a stable, thin coating layer with excellent adsorption capabilities.…”