Abstract:The synthesis of nanocomposite materials based on poly(methyl methacrylate) and graphene oxide (GO) is presented using the in situ polymerization technique, starting from methyl methacrylate, graphite oxide, and an initiator, and carried out either with (solution) or without (bulk) in the presence of a suitable solvent. Reaction kinetics was followed gravimetrically and the appropriate characterization of the products took place using several experimental techniques. X-ray diffraction (XRD) data showed that graphite oxide had been transformed to graphene oxide during polymerization, whereas FTIR spectra revealed no significant interactions between the polymer matrix and GO. It appears that during polymerization, the initiator efficiency was reduced by the presence of GO, resulting in a reduction of the reaction rate and a slight increase in the average molecular weight of the polymer formed, measured by gel permeation chromatography (GPC), along with an increase in the glass transition temperature obtained from differential scanning calorimetry (DSC). The presence of the solvent results in the suppression of the gel-effect in the reaction rate curves, the synthesis of polymers with lower average molecular weights and polydispersities of the Molecular Weight Distribution, and lower glass transition temperatures. Finally, from thermogravimetric analysis (TG), it was verified that the presence of GO slightly enhances the thermal stability of the nano-hybrids formed.
Nanocomposite materials based on
poly(butyl methacrylate) and either
graphene oxide (GO) or functionalized graphene oxide (F-GO) were produced
using the in situ bulk radical polymerization technique. It was found
that the Hummers method results in a higher degree of oxidation, compared
to the Staudenmaier, whereas F-GO was produced using a silane-modifying
agent. Polymerization kinetics were studied both experimentally and
theoretically, and it was found that the presence of hydroxyl groups
in the surface of GO results in scavenging the primary initiator radicals,
thus reducing the initiator efficiency and the reaction rate, whereas
the number-average molecular weight of the polymer formed was increased.
The presence of F-GO affected the polymerization kinetics in a different
way resulting in partially grafted structures. The theoretical study
included the addition of a phenomenological transfer to the polymer
side-reaction to account for the polymerization occurring at the F-GO
surface.
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