Nanocomposites and nanomaterials

Synthesis and properties of the core/shell halloysite/polyaniline nanocomposites
Noskov Yu.V.1, Ogurtsov N.A.1, Myronyuk I.E.1, Bliznyuk V.N.2, Pud A.A.1
1 V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, NAS of Ukraine, , 50 Kharkivske shose, Kyiv 02160, Ukraine. 
E-mail: alexander.pud@gmail.com; pud@bpci.kiev.ua
2 Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC 29634-0919 USA.

Halloysite is biocompatible alumosilicate nanotubular clay known due to its capacity to work as efficient multifunctional adsorbent, which is able to entrap, store and release drugs, nucleic acids, proteins, anticorrosion agents, biocides, etc. [1]. This capacity can be significantly enhanced in its nanocomposites with conducting polymer polyaniline, having own multifunctionality and delocalized charges with ability to interact with different substances. However, while such nanocomposites are known since beginning of this century [2] and suggested for use in different important applications (e.g. [3]) there is still a lack of information on factors influencing peculiarities of their synthesis/formation and properties that in turn hampers a development of such materials. 
Our work is directed to fill this gap in our knowledge through investigation of changes of physical-chemical parameters of chemical oxidative aniline polymerization in the presence of halloysite nanotubes and organic acid-dopant, of the polyaniline yield and of the composition and properties of such materials. Among the most important findings of our work we consider the relationships which reveal effects of the reagents ratio on pH/open circuit potential of the reaction mixture and the rate of the polymerization process, as well as on the quality, molecular structure and charge carriers of the polyaniline phase in the formed halloysite/polyaniline nanocomposites. These findings reveal specific interactions of the polyaniline phase with the halloysite nanotubes. 

1.	Lvov Yu. et al. Halloysite Clay Nanotubes for Loading and Sustained Release of Functional Compounds // Adv. Mater. – 2016. -28. –P. 1227–1250.
2.	Luca V., Thomson S. Intercalation and polymerisation of aniline within a tubular aluminosilicate // J. Mater. Chem. – 2000. – 10. – P. 2121–2126.
3.	Wang Y. et al. Enhancing the CO2 separation performance of SPEEK membranes by incorporation of polyaniline-decorated halloysite nanotubes// J. Membr. Sci. – 2019. – 573. – P. 602-611.