Investigation into the Potential Migration of Nanoparticles from Laponite-Polymer Nanocomposites

Abstract

In this study, the migration potential of laponite, a small synthetic nanoclay, from nanocomposites into foods was investigated. First, a laponite/ethylene vinyl acetate (EVA) masterbatch was compounded several times and then extruded into thin low-density polyethylene (LDPE) based films. This way, intercalation and partial exfoliation of the smallest type of clay was achieved. Migration of laponite was investigated using Asymmetric Flow Field-Flow Fractionation (AF4) with Multi-Angle Laser Light Scattering (MALLS) detection. A surfactant solution in which laponite dispersion remained stable during migration test conditions was used as alternative food simulant. Sample films with different loadings of laponite were stored for 10 days at 60 °C. No migration of laponite was found at a limit of detection of 22 µg laponite per Kg food. It can be concluded that laponite (representing the worst case for any larger structured type of clay) does not migrate into food once it is incorporated into a polymer matrix.

Investigations into the Potential Abrasive Release of Nanomaterials due to Material Stress Conditions—Part B: Silver, Titanium Nitride, and Laponite Nanoparticles in Plastic Composites

“…In our previous studies the diffusion (in polymer) controlled migration potential of TiN-NP [2], Ag-NP [1], and Laponite [3] from LD-PE-based composites was investigated. The same nanocomposites were now used to investigate the potential mechanical release of nanoparticles.…”

“…In a previous study [3] it was demonstrated that AF4/MALLS was suitable for the characterization and quantification of laponite particles dispersed in an aqueous surfactant solution (2000 mg/L NovaChem). However, AF4/MALLS showed limitations caused by superimpositions in the fractogram when the sample matrix became too complex.…”

“…Nanomaterials are used in consumer products like food packaging articles which require profound knowledge on the potential release of nanomaterials into foods for proper risk assessment. In our previous works, based on comprehensive migration testing using plastics nanocomposites with incorporated silver nanoparticles (Ag-NPs) [1], nanotitanium nitride (TiN) [2], and nanolaponite [3], we could not find any detectable migration and together with theoretical considerations we concluded that migration of nanoparticles from plastic food packaging materials in general is not possible according to Fickian Law of diffusion as long as the particles are larger than 3-4 nm (in case of polyolefins) or 1-2 nm (for PET and similar polymers) in diameter [4] and when the nanomaterial is fully covered with polymer (i.e., does not stick out of the polymer). Since such small nanomaterial sizes are not used in food contact nanocomposites exposure of the consumer due to diffusion-controlled migration of nanomaterials can be excluded.…”

Food Packaging Based on Nanomaterials

“…The toxicological aspects of packaging nanomaterials are also covered in this Special Issue through the work of Bott and Franz [13], who studied nanoparticle migration from laponite–polymer nanocomposites. It is well-known that, in order to enhance the properties of nanoclay-containing polymeric nanocomposites, the nanoclays need to be properly exfoliated and intercalated within the polymeric matrix [2].…”

“…Therefore, in this work, sample films with different laponite loadings were stored at high temperature (60 °C) to accelerate release, and migration in a food simulant was studied. No migration of laponite was detected once it was incorporated into the polymer matrix using a limit of detection of 22 µg laponite per Kg food, thereby assuring the safety of this specific material for food packaging applications [13].…”