Self‐Sterilized EVOH‐TiO₂ Nanocomposites: Interface Effects on Biocidal Properties

Abstract

Nanocomposite materials obtained by TiO2 incorporation into ethylene–vinyl alcohol copolymers, extensively used in food packaging, are prepared via a straightforward melting process. The structural characteristics of the nanocomposites are examined using wide and small angle X‐ray scattering (WAXS/SAXS), and vibrational infrared and Raman spectroscopies. A microscopy (SEM/TEM) study shows that the materials obtained are highly homogeneous at the nanometric scale, exhibiting an intimate contact between both the organic and inorganic components. TiO2 incorporation into this polymer matrix renders self‐sterilized nanocomposite materials upon light excitation, which are tested against nine micro‐organisms (gram‐positive and gram‐negative bacteria, cocci, and yeasts) typically involved in food contamination and/or degradation. Overall, the nanocomposites display an impressive performance in the killing of all micro‐organisms with a maximum for an oxide content between 2–5 wt %. The measurement of the physico‐chemical properties together with the structural characterization of the materials provide conclusive evidence that the nanocomposites biocidal capability born of the nanometric organo‐inorganic interface and rationalize the existence of a maximum as a function of the TiO2 content.

Rheological and structural details of biocidal iPP-TiO2 nanocomposites

“…The excellent biocidal capabilities exhibited by nanocomposites based on a metallocene iPP and TiO 2 have been reported in previous works [3][4][5], varying either the nanoparticle composition, this ranging from 0.5 to 5 wt.%, at a given compatibilizer content, or the interfacial agent fraction at a specific TiO 2 content of 2 wt.%. This striking antimicrobial activity has been also found by using an ethylene-vinyl alcohol copolymer as polymeric matrix [6][7][8].…”

“…Compared with other biocidal agents, an excellent power for destruction of regular bacteria, as B. stearothermophilus, E. coli, S. aureus, P. jadini, and other microorganisms widely present in the environment that cause infections and serious illness, as P. aeruginosa and E. faecalis, has been found in titania nanoparticle-polypropylene nanocomposites [3][4][5].…”

“…This striking antimicrobial activity has been also found by using an ethylene-vinyl alcohol copolymer as polymeric matrix [6][7][8]. The existence of energy/charge transfer(s) through these polymer/oxide interfaces and the subsequent development of new electronic states within the nanocomposite system [9] are behind this optimal germicide capability.…”

Copolymers of acrylonitrile with quaternizable thiazole and triazole side-chain methacrylates as potent antimicrobial and hemocompatible systems

“…In addition, it is important to mention that highly efficacious and non-hemolytic antimicrobial quaternized polycarbonates, described by Yang and Hedrick groups, are able to eliminate E. coli and S. aureus bacteria in 4 h [46,51]. Also, in comparison with reported results of composites consisting of a cationic poly(vinylpyridine) matrix and embedded silver bromide nanoparticles, these systems present 4 log-reduction in 1 h toward E. coli [80], while titania nanocomposites give 3-4 log-reduction in 15-30 min for different bacteria and fungi [81,82]. This gives an idea about the efficiency and responsiveness of our systems.…”

TiO<sub>2</sub> Films Synthesis over Polypropylene by Sol-Gel Assisted with Hydrothermal Treatment for the Photocatalytic Propane Degradation

“…One of the main issues associated with coatings over polymer substrates is the coating bonding to the substrate. In the particular case of the synthetized coatings in this work, anchoring of these can be attributed to the fact that OH-groups from TiO 2 nanoparticles act as bonding sites via Hydrogen Bridge to polypropylene as claimed by Cerrada et al [22]. Figure 5 describes the synthesis mechanism of the sol-gel process followed by the hydrothermal treatment [23] and finally, the proposed anchoring mechanism of the TiO 2 to polypropylene.…”