Innovative Hyperbranched Polybenzoxazine-Based Graphene Oxide-Poly(amidoamines) Nanomaterials.

Elena Iuliana Bîru,Horia Iovu,Sorina Alexandra Gârea

doi:10.3390/polym12102424

Elena Iuliana Bîru, Horia Iovu + Show 1 more

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https://doi.org/10.3390/polym12102424

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Abstract

The covalent functionalization of graphene oxide (GO) surface with hyperbranched benzoxazine (BZ) structures has been achieved using poly(amidoamine) dendrimers (PAMAM) of different generations. By increasing the PAMAM generation, multiple benzoxazine rings were synthesized decorating the GO layers. The polymerization process and the exfoliation behavior were investigated. The novel BZ-functionalized GO hybrid materials were characterized by a combination of techniques such as FT-IR, XPS, and 1H-NMR for the confirmation of benzoxazine formation onto the GO layer surfaces. Raman and XRD investigation showed that the GO stacking layers are highly disintegrated upon functionalization with hyperbranched benzoxazine monomers, the exfoliation being more probably to occur when lower PAMAM generation (G) is involved for the synthesis of hybrid GO-BZ nanocomposites. The polymerization of BZ rings may occur either between the BZ units from the same dendrimer molecule or between BZ units from different dendrimer molecules, thus influencing the intercalation/exfoliation of GO. DSC data showed that the polymerization temperature strongly depends on the PAMAM generation and a significant decrease of this value occurred for PAMAM of higher generation, the polymerization temperature being reduced with ~10 °C in case of GO-PAMAM(G2)-BZ. Moreover, the nanoindentation measurements showed significant mechanical properties improvement in case of GO-PAMAM(G2)-BZ comparing to GO-PAMAM(G0)-BZ in terms of Young modulus (from 0.536 GPa to 1.418 GPa) and stiffness (from 3617 N/m to 9621 N/m).

Highlights

Nowadays the synthesis of versatile polymers represents an emerging demand for industrial sectors that require easy to handle, yet high-performance polymers for construction materials, electronic devices, or aerospace industry
graphene oxide (GO)-COOHsurface surfaceloading loadingwith withdendrimer dendrimer structures was investigated through probe the chemical attachment of hyperbranched poly(amidoamines)
New nanomaterials based on benzoxazine (BZ)-functionalized graphene oxide (GO)

Summary

Introduction

Nowadays the synthesis of versatile polymers represents an emerging demand for industrial sectors that require easy to handle, yet high-performance polymers for construction materials, electronic devices, or aerospace industry. Polybenzoxazines (PBZs) are a unique class of thermoset resins that in many cases surpass the phenolic and epoxy resin properties in terms of thermal resistance, UV and chemical stability, water absorption, void formation, and volumetric shrinkage during the curing process [1,2,3]. These remarkable features of PBZs are generated by the rich molecular flexibility of the benzoxazine monomers that allows the synthesis of complex polymerizable structures for tailored properties [4]. PBZ resins are produced via further thermal ring-opening polymerization (ROP) forming numerous –OH groups that are inter- and intramolecularly hydrogen

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