Research paperDevelopment, characterization and cytotoxicity of novel silane-modified clay minerals and nanocomposites intended for food packaging

- Two different organoclays were developed from Mt using silanes as modifiers.
- Better technological results were obtained with the 3-aminopropylthriethoxisilane modified clay mineral.
- PP-3-aminopropylthriethoxisilane modified clay mineral nanocomposites showed improved mechanical and barrier properties.
- Microbiological growth has been reduced with PP-3-aminopropylthriethoxisilane modified clay mineral nanocomposites.
- Vinyltrimethoxysilane modified clay mineral produced a decrease in cell viability in both cell lines tested.

Layered silicates are largely used to develop polymer nanocomposites with improved physical properties compared to the original polymeric matrix. In this work, the silylation of sodium montmorillonite (Mt) was performed in distilled water using 3-aminopropyltriethoxysilane and vinyltrimethoxysilane, obtaining two different silane modified clay minerals named Clay3 and Clay4, respectively. Clay3 indicated a better profile with a notable increase in the interlayer space compared to Mt. For this reason, Clay3 was selected to scale up its production and to be incorporated in polypropylene (PP) matrix. The PP-Clay3 nanocomposite showed an enhancement in elasticity, a reduction of 15% in the oxygen transmission rate and important antimicrobial effects in comparison to pristine PP. Also, for the first time, cytotoxic effects in human cell lines exposed to Clay3 and Clay4 were evaluated. No cytotoxic damage was observed after Clay3 exposure but an important decrease in cell viability was produced by Clay4. The PP-Clay3 nanocomposite is an attractive alternative for the food packaging industry although further work is needed to get better results in the case of Clay4. Moreover, individual case by case evaluation of clay minerals under different conditions is required in order to obtain the most complete toxicity information.

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