resumo
Polylactide (PLA) with a terminal triple bond was synthesized by organocatalyzed ring-opening polymerization and coupled with azide-functionalized graphene oxide (GO) through an azide-alkyne cycloaddition "click" reaction. The functionalized graphenic species involved were analyzed by spectroscopic techniques (FT-IR, solid state C-13 NMR, Raman), which confirmed the coupling of PLA and GO. Additionally, an in depth study of the prepared GO, intermediates and GO-g-PLA hybrid was carried out that sheds light on the mechanisms involved in the functionalization path. The obtained GO-g-PLA hybrid, containing at least 20% of biopolymer, presented an exfoliated graphenic structure, as established by XRD. The conditions used in the grafting of the PIA chains inhibited the crystallization and melting observed for the free polymer. Furthermore, the graphene oxide seems to be reduced during functionalization, which can also be an advantage. Nanocomposites were obtained as solvent-cast films, prepared by dispersion of the GO-g-PLA hybrid in commercial PEA. Preliminary results regarding the performance of these nanocomposites, obtained by DSC and DMA, highlighted the effect of functionalization. Loading values as low as 0.5% suffice to improve the mechanical properties over a broad temperature range due to the high surface area resulting from the good dispersibility of polymer functionalized nanofillers and/or their effect on the polymer chain organization. (C) 2015 Elsevier B.V. All rights reserved.
palavras-chave
RING-OPENING POLYMERIZATION; POLY-LACTIC-ACID; EXFOLIATED GRAPHITE OXIDE; CLICK CHEMISTRY; CRYSTALLIZATION KINETICS; POLY(LACTIC ACID); MECHANICAL-PROPERTIES; ALIPHATIC POLYESTERS; NANOCOMPOSITES; SHEETS
categoria
Materials Science
autores
Campos, JM; Ferraria, AM; do Rego, AMB; Ribeiro, MR; Barros-Timmons, A
nossos autores
Ana Margarida Madeira Viegas de Barros Timmons
Professor associado
João Miguel Campos
Bolseiro de pós-Doutoramentoagradecimentos
This work was funded through project CICECO - Aveiro Institute of Materials (ref. FCT UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when applicable co-financed by FEDER under the PT2020 Partnership Agreement.; This work is also supported by the