Nanocomposite films and coatings using inorganic nanobuilding blocks (NBB): current applications and future opportunities in the food packaging sector

Abstract

The aim of this review is to provide an in-depth overview on the use of inorganic nano-sized entities for the generation of nanocomposite materials in the form of films and coatings for food packaging applications.According to recent trends toward "green" strategies, special focus has been dedicated to the development of nanocomposite coatings obtained using biopolymers as the main polymer matrix. After a first introductive part, the discussion has been addressed to the use of inorganic fillers, metals and metal-oxides, zeolites, and graphene. For each class of filler, a first 'in-depth' description of the most relevant physicochemical properties for the food packaging sector has been followed by case-by-case references to recent developments and envisaged implementations. The technical aspects that may be crucial in the design and end use of (bio)nanocomposite coatings have been covered in the last part of this work, which also includes an updated list of current applications on nano-sized inorganic fillers in the food packaging field.

High diffusion barrier and piezoelectric nanocomposites based on polyvinylidene fluoride‐trifluoroethylene copolymer and hydrophobized clay

“…A further advantage of the addition of impermeable fillers with high aspect ratio, such as clay or graphene sheets into polymers is to increase the gas barrier properties of the latter. This is particularly true when exfoliation of the original layered structure of the filler is obtained, resulting in well‐known “tortuous path” effect . Besides the filler morphology, volume fraction, and dispersion state, the intrinsic permeability of the polymer and of the filler/polymer interface impact the composite permeability .…”

Evaluation of crystallinity and gas barrier properties of films obtained from PLA nanocomposites synthesized via “in situ” polymerization of l-lactide with silane-modified nanosilica and montmorillonite

“…Also nanosilica has been largely used to improve the properties of polymers such as PLA, to control rheological behavior or as a structural reinforcement [18][19][20]; as reported for clay particles, also with nanosilica it is important to obtain a very good dispersion of the mineral in the polymer matrix. Most of the scientific literature deals with nanocomposites prepared via blending or dissolving the polymer in a nanosilica suspension and re-precipitating the polymeric matrix, but these techniques sometimes could not be efficient enough to obtain materials with good properties [16,[21][22][23][24][25]. It is also necessary to add relatively high quantities of nanoparticles -between 4% and 10% on the total weight of the polymer -to have relevant effects on gas permeability reduction [26].…”

Transparent Pullulan/Mica Nanocomposite Coatings with Outstanding Oxygen Barrier Properties

“…The bigger advantage of using synthetic clays is represented by standardized physicochemical properties. Unlike natural clays, micas that are able to expand with very high aspect ratios have been obtained by synthetic pathways, which eventually promote better and higher quality dispersion in the polymer matrix [1,2]. For this reason, the use of synthetic NBBs as attractive nanomaterials is rising at both the academic and industrial level.…”

“…Layered silicate minerals include several classes and many groups that, in turn, account for different mineral species that are potentially suitable to produce nanocomposites. However, only few of these minerals (especially montmorillonite) have been widely exploited thus far [1]. Commercially available natural and organically modified are disadvantaged by their limited aspect ratios (α) <100 and high surface charge heterogeneity.…”

“…However, most examples concerned the incorporation of the inorganic phase directly into the bulky biopolymer. The use of fillers within coatings made of biopolymers has been proposed only very recently to produce bionanocomposite coatings to improve the properties of a plastic substrate without jeopardizing its original attributes, to optimize cost efficiency, and to reduce environmental impact [1,8]. Bionanocomposite coatings were successfully produced by using natural montmorillonite (Na + -MMT) [9] and graphene oxide [10] to improve the oxygen barrier properties, even at high relative humidity values, or in combination with microfibrillated cellulose (MFC) [11] and borax [12] to produce biocoatings with enhanced mechanical and permeability properties.…”