title: Competitive interactions and controlled release of a natural antioxidant from halloysite nanotubes.
abstract: Halloysite nanotubes used as potential carrier material for a controlled release stabilizer in polyethylene were thoroughly characterized with several techniques including the measurement of specific surface area, pore volume and surface energy. The high surface energy of the halloysite results in the strong bonding of the additive to the surface. Dissolution experiments carried out with eight different solvents for the determination of the effect of solvent characteristics on the amount of irreversibly bonded quercetin proved that adsorption and dissolution depend on competitive interactions prevailing in the system. Solvents with low polarity dissolve only surplus quercetin adsorbed in multilayers. Polyethylene is a very apolar polymer forming weak interactions with every substance; quercetin dissolves into it from the halloysite surface only above a critical surface coverage. Stabilization experiments confirmed that strong adhesion prevents dissolution and results in limited stabilization efficiency. At larger adsorbed amounts better stability and extended effect were measured indicating dissolution and controlled release.
authors.affiliation: Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary. Electronic address: jhari@mail.bme.hu.
authors.forename: József
authors.initials: J
authors.lastname: Hári
authors.affiliation: Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary. Electronic address: gyurkiadam@gmail.com.
authors.forename: Ádám
authors.initials: Á
authors.lastname: Gyürki
authors.affiliation: Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary. Electronic address: fenuiww@gmail.com.
authors.forename: Márk
authors.initials: M
authors.lastname: Sárközi
authors.affiliation: Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary. Electronic address: foldes.eniko@ttk.mta.hu.
authors.forename: Enikő
authors.initials: E
authors.lastname: Földes
authors.affiliation: Laboratory of Plastics and Rubber Technology, Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, H-1521 Budapest, P.O. Box 91, Hungary; Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1519 Budapest, P.O. Box 286, Hungary. Electronic address: bpukanszky@mail.bme.hu.
authors.forename: Béla
authors.initials: B
authors.lastname: Pukánszky
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry*; D000077215:Clay; D015394:Molecular Structure; D043942:Nanotubes / Q000737:chemistry*; D010316:Particle Size; D020959:Polyethylene / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D000975:Antioxidants; D020959:Polyethylene; D000077215:Clay
keywords: Controlled release; Halloysite; Interaction; Nanotube; Natural antioxidant; Quercetin