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Abstract Super-crosslinked epoxy nanocomposites containing N-octadecyl-N'-octadecyl imidazolium iodide (IM)-functionalized montmorillonite (MMT-IM) nanoplatelets were developed and examined for cure kinetics, viscoelastic behavior and thermal degradation kinetics. The structure and morphology of [...]

• By cathodic electrodeposition the bare, bulk- and surface-modified Fe 3 O 4 nanoparticles were obtained. • Fe 3 O 4 , Mn-doped Fe 3 O 4 , and PVP-functionalized Mn-doped Fe 3 O 4 nanoparticles were synthesized. • Compared curability of nanocomposites containing Mn-doped and PVP-functionalized Mn-doped Fe 3 O 4. • Labeled epoxy nanocomposites in terms of Cure Index as, Poor , Good , and Excellent. Poor , Good , and Excellent are labels for thermoset composites cured at a given heating rate applied in nonisothermal differential scanning calorimetry (DSC). Here the potential of surface- and bulk-surface functionalized nanoparticles to curing with epoxy has been unraveled. Cathodic electrodeposition technique was used to yield three types of magnetic iron oxides (MIOs): MIOs, polyvinylpyrrolidone (PVP) surface-functionalized MIOs (PVP/MIOs), and PVP/MIOs in which Mn2+ cations were partially doped in (Mn-doped PVP/MIOs). The resulting nanoparticles were characterized for surface by Fourier-transform infrared spectroscopy (FTIR), for size and size distribution by field-emission scanning electron microscopy (FE-SEM), for bulk composition by X-Ray diffraction (RXD) and for supermagnetic properties by vibrating sample magnetometry (VSM). Epoxy nanocomposites containing 0.1 wt.% of PVP/MIOs and Mn-doped PVP/MIOs underwent nonisothermal DSC at four heating rates. Curing epoxy with PVP/MIOs and Mn-doped PVP/MIOs was qualified by Cure Index , which demonstrated the effect of bulk and surface modification of MIOs. Overall, Good cure was the case for epoxy nanocomposites containing Mn-doped PVP/MIOs due to accelerating effect of PVP and Mn2+ on crosslinking between epoxy and amine. [ABSTRACT FROM AUTHOR]

• Synthesized electrochemically and characetrized Fe 3 O 4 and Gd2+-Fe 3 O 4 , and PEG-Gd2+-Fe 3 O 4. • Compared the curability of nanocomposites by the aid of Cure Index concept. • Replacement of Fe2+ by Gd2+ activated Fe 3 O 4 surface and enhanced EG grafting onto Fe 3 O 4. • Replacement of Gd2+-Fe 3 O 4 with PEG-Gd2+-Fe 3 O 4 changed cure label of epoxy from Poor to Good. Lanthanide-doped Fe 3 O 4 nanoparticles were synthesized and functionalized via electrodeposition method using which gadolinium cations (Gd3+) were exchanged partially with Fe3+ in the ferrite lattice. Polyethylene glycol (PEG) was grafted onto the surface of Fe 3 O 4 and Gd-doped Fe 3 O 4 to study its potential for epoxy curing. X-Ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometry (VSM) confirmed successful synthesis, and bulk- and surface modification of Fe 3 O 4 and Gd-Fe 3 O 4 and PEG-Gd-Fe 3 O 4. Nonisothermal differential scanning calorimetry (DSC) on samples containing 0.1 wt.% of nanoparticles was indicative of Poor cure for epoxy/Fe 3 O 4 and epoxy/Gd-Fe 3 O 4 , while Excellent cure for epoxy/PEG-Gd-Fe 3 O 4 , demonstrating promising role of Gd in epoxy ring opening. [ABSTRACT FROM AUTHOR]

• Synthesized magnetic nanoparticles (MNPs) through controlled cathodic electro-deposition. • Functionalized surface and bulk of MNPs with PEG macromolecule and Zn2+ cations, respectively. • Epoxy/PEG-MNPs labeled Poor at low and high heating rates, but Good at intermediate rates. • Epoxy/Zn-doped PEG-MNPs labeled Good irrespective of heating rate applied in DSC. • Epoxy curing was completed by combined bulk and surface modification of MNPs. Nanoparticles govern early (chemical-controlled) and late (diffusion-controlled) stages of epoxy crosslinking, respectively. Surface functionalization of nanoparticles with macromolecules was recognized as an effective route to compensate for inadequate diffusion-controlled crosslinking. However, the effect of bulk composition amended with cations having catalytic effect towards epoxy ring opening has remained hitherto undescribed. In this work, cathodic electrochemical method was applied to obtain naked iron oxide nanoparticles (IONPs), polyethylene glycol (PEG) capped IONPs (PEG-IONPs) and zinc-doped IONPs (Zn-doped PEG-IONPs) for evaluation of the effects of surface (alone) and surface-bulk (concurrent) modification of IONPs. Various techniques including FTIR, XRD, VSM, and FE-SEM were employed to probe into changes in the surface and bulk of nanoparticles. Cure Index calculated based on nonisothermal differential scanning calorimetry (DSC) allowed for labeling epoxy nanocomposites as Poor ( Red ) or Good ( Blue ) cured networks. Partial substitution of Fe2+ cations by Zn2+ in the bulk of Zn-doped PEG-IONPs with respect to PEG-IONPs labeled their corresponding epoxy nanocomposites in Blue and Red . Although at low and high heating rates epoxy/PEG-IONPs was labeled Red , epoxy/Zn-doped PEG-IONPs nanocomposites was unconditionally labeled Blue thanks to a more significant catalytic effect springing from Zn2+ cations in Zn-doped IONPs compared to hydroxyl groups alone in PEG-IONPs. [ABSTRACT FROM AUTHOR]

• Isoconversional methods unraveled tendency of Zn x Fe 3 -x O 4 to cure with epoxy. • Non-catalytic and autocatalytic reactions contributed to epoxy/Zn x Fe 3 -x O 4 curing were quantified. • Molecular collision as a measure of interaction was increased for epoxy by addition of Zn x Fe 3 -x O 4. • Doping Fe 3 O 4 in Zn compensated for restricted autocatalytic reactions in epoxy/Fe 3 O 4 system. Epoxy nanocomposites containing electrochemically synthesized Fe 3 O 4 and Zn-doped Fe 3 O 4 (Zn-Fe 3 O 4) were prepared and their cure behavior and kinetics were discussed by the aid of nonisothermal differential scanning calorimetry and isoconversional methods. The results of differential and integral isoconversional methods indicated that addition of Fe 3 O 4 nanoparticles to epoxy decreases the activation energy of the epoxy nanocomposite with respect to the unfilled epoxy due to the steric hindrance effect as a consequence of aggregation of magnetic Fe 3 O 4 nanoparticles. By contrast, Zn-Fe 3 O 4 nanoparticles facilitated crosslinking of epoxy due to the autocatalytic reaction of OH groups on the surface of nanoparticles with epoxy groups. [ABSTRACT FROM AUTHOR]