IP: 46.148.127.213 On: Wed, 26 Dec 2018 02:39:23 Copyright: American Scientific Publishers Delivered by Ingenta Copyright © 2019 American Scientific Publishers All rights reserved Printed in the United States of America Article Journal of Nanoscience and Nanotechnology Vol. 19, 2599–2605, 2019 www.aspbs.com/jnn Polyethylene/Organo–Inorgano Vermiculites and Their Antimicrobial Properties Marianna Hundáková 1 2 ∗ , Marta Valášková 1 , Erich Pazdziora 3 , and Dušan Kimmer 4 1 Nanotechnology Centre, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, 708 33 Ostrava-Poruba, Czech Republic 2 Regional Materials Science and Technology Centre, VŠB-Technical University of Ostrava, 17. listopadu 15/2172, 70833 Ostrava-Poruba, Czech Republic 3 National Reference Laboratory, Institute of Public Health in Ostrava, Partyzánské námˇ estí 7, 702 00 Ostrava, Czech Republic 4 SPUR a.s., tˇ r. T. Bati 299, 764 22 Zlín, Czech Republic Clay mineral vermiculite was treated with silver and copper nitrate solutions and samples were subsequently modified with organic compound (dodecylamine) via solid-solid melt intercalation. Prepared organo–inorgano vermiculites were used as nanofillers to the polyethylene matrix. Mix- tures of polyethylene with vermiculite nanofillers, prepared by melt compounding technique, were pressed into thin plates. Structure changes of prepared powder vermiculite nanofillers and polyethy- lene/vermiculite composites were studied by X-ray diffraction analysis. The X-ray diffraction pat- terns of vermiculite nanofillers confirm intercalation of dodecylamine into the vermiculite interlayer. Antimicrobial properties of powder vermiculite nanofillers were evaluated by the minimum inhibitory concentration of samples which is needed to completely stop the bacterial growth and polyethy- lene/vermiculite composites were evaluated by the number of colony forming units survived on surfaces of composite plates. Different bacterial strains were studied: (1) Gram-positive, represented by bacteria Staphylococcus aureus and Enterococcus faecalis, (2) Gram-negative, represented by bacteria Escherichia coli and Pseudomonas aeruginosa, and (3) yeast, Candida albicans. Powder vermiculite nanofillers and surfaces of polyethylene/vermiculite composites showed good antimicro- bial effect against tested bacteria and yeast. Powder vermiculite nanofillers show antimicrobial effect already after 30 minutes of tested time. Composite plates exhibited decrease of colony forming units number about 5–7 logarithmic orders depending on bacteria after 24 hours of tested time. Keywords: Vermiculite, Dodecylamine, Polyethylene, X-ray Diffraction, Antibacterial Activity. 1. INTRODUCTION Vermiculite is a 2:1 layered clay mineral with structure composed of an octahedral sheet sandwiched between two opposing tetrahedral sheets. Octahedral (Al 3+ ) and tetrahedral (Si 4+ ) cations can be substituted by cations with lower valency (Al 3+ , Mg 2+ , Fe 3+ , Fe 2+ ) resulting in arising of the negative charge on vermiculite layers. 1 The negative charge on vermiculite layers supports cation exchange, intercalation or adsorption of various cations or surfactants. Intercalated by organic surfactants vermiculite becomes organophilic and can be utilized as nanofiller to polymer matrix in order to improve the mechanical or ther- mal properties and provide the new functional features to polymer composites. 2 ∗ Author to whom correspondence should be addressed. Several authors used organic surfactant dodecy- lamine (DA) for clay mineral modification and studied their structural characteristics. 3–5 Montmorillonite inter- calated with DA was prepared and studied as a poten- tial adsorbent of hexavalent chromium from wastewater. 6 7 Kaolinite was intercalated with DA into the interlayer space by utilizing the methanol treated kaolinite and DMSO intercalation complex as an intermediate. 8 In our previous work, natural vermiculite with silver and copper or intercalated with DA were studied independently as nanofillers into the PE matrix. 9 10 In present work, vermiculite with silver and cop- per was modified to organovermiculite forms with dodecylamine and used as nanofiller to polyethylene. Prepared materials were characterized by X-ray diffrac- tion analysis and antimicrobial activity was tested on (1) Gram-positive (G + ) bacteria, Staphylococcus aureus J. Nanosci. Nanotechnol. 2019, Vol. 19, No. 5 1533-4880/2019/19/2599/007 doi:10.1166/jnn.2019.15852 2599