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

Authors


  • Financial support from CSIC and MEC is acknowledged by Dr. A. Kubacka and Ms. C. Serrano for their I3P postdoctoral and FPU predoctoral grants, respectively. This work was supported by the CSIC under the projects PIF200580F0101, PIF200560F0102, PIF200560F103 and PIF200570F104. The synchrotron work was supported by the European Community – Research Infrastructure Action under the FP6 “Structuring the European Research Area” Programme (through the Integrated Infrastructure Initiative “Integrating Activity on Synchrotron and Free Electron Laser Science”), contract RII3-CT-2004-506008 (IA-SFS). We thank the collaboration of the Hasylab personnel in the soft-condensed matter beamline A2, especially Dr. S. S. Funari. Supporting Information is available online from Wiley InterScience or from the authors.

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.

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