Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation-Network Degradation Correlation

Maryam Jouyandeh; Vahideh Akbari; Seyed Mohammad Reza Paran; Sébastien Livi; Luanda Lins; Henri Vahabi; Mohammad Reza Saeb

doi:10.3390/nano11081990

Epoxy/Ionic Liquid-Modified Mica Nanocomposites: Network Formation-Network Degradation Correlation

Nanomaterials (Basel). 2021 Aug 3;11(8):1990. doi: 10.3390/nano11081990.

Authors

Maryam Jouyandeh¹, Vahideh Akbari¹, Seyed Mohammad Reza Paran², Sébastien Livi³, Luanda Lins⁴, Henri Vahabi¹, Mohammad Reza Saeb⁵

Affiliations

¹ Université de Lorraine, CentraleSupélec, LMOPS, F-57000 Metz, France.
² Center of Excellence in Electrochemistry, School of Chemistry, College of Science, University of Tehran, Tehran 1417935840, Iran.
³ Université de Lyon, CNRS, UMR 5223, Ingénierie des Matériaux Polymères, INSA Lyon, F-69621 Villeurbanne, France.
⁴ Université de Lyon, CNRS, UMR 5510, MATEIS, INSA Lyon, F-69621 Villeurbanne, France.
⁵ Department of Polymer Technology, Faculty of Chemistry, Gdańsk University of Technology, G. Narutowicza 11/12, 80-233 Gdańsk, Poland.

Abstract

We synthesized pristine mica (Mica) and N-octadecyl-N'-octadecyl imidazolium iodide (IM) modified mica (Mica-IM), characterized it, and applied it at 0.1-5.0 wt.% loading to prepare epoxy nanocomposites. Dynamic differential scanning calorimetry (DSC) was carried out for the analysis of the cure potential and kinetics of epoxy/Mica and epoxy/Mica-IM curing reaction with amine curing agents at low loading of 0.1 wt.% to avoid particle aggregation. The dimensionless Cure Index (CI) was used for qualitative analysis of epoxy crosslinking in the presence of Mica and Mica-IM, while qualitative cure behavior and kinetics were studied by using isoconversional methods. The results indicated that both Mica and Mica-IM improved the curability of epoxy system from a Poor to Good state when varying the heating rate in the interval of 5-15 °C min^-1. The isoconversional methods suggested a lower activation energy for epoxy nanocomposites with respect to the blank epoxy; thus, Mica and Mica-IM improved crosslinking of epoxy. The higher order of autocatalytic reaction for epoxy/Mica-IM was indicative of the role of liquid crystals in the epoxide ring opening. The glass transition temperature for nanocomposites containing Mica and Mica-IM was also lower than the neat epoxy. This means that nanoparticles participated the reaction because of being reactive, which decelerated segmental motion of the epoxy chains. The kinetics of the thermal decomposition were evaluated for the neat and mica incorporated epoxy nanocomposites epoxy with varying Mica and Mica-IM amounts in the system (0.5, 2.0 and 5.0 wt.%) and heating rates. The epoxy/Mica-IM at 2.0 wt.% of nanoparticle showed the highest thermal stability, featured by the maximum value of activation energy devoted to the assigned system. The kinetics of the network formation and network degradation were correlated to demonstrate how molecular-level transformations can be viewed semi-experimentally.

Keywords: cure index; cure kinetics; degradation kinetics; epoxy nanocomposite; ionic liquids; mica.