Complex Kinetic Pathway of Furfuryl Alcohol Polymerization Catalyzed by Green Montmorillonite Clays

Abstract

Furfuryl alcohol (FA) which is derived from lignocellulosic biomass polymerizes into poly(furfuryl alcohol) (PFA) under acidic catalysis. A greener and more sustainable catalytic route was proposed in order to replace hazardous acidic catalysts. Organically modified montmorillonite (Org-MMT) and, in comparison, sodium MMT (Na-MMT) are used to evaluate the catalytic effect on the FA polymerization. X-ray diffraction (XRD) and transmission electronic microscopy (TEM) show that clay layers have been exfoliated during polymerization. Additional FTIR spectroscopy measurements confirm that furanic oligomers have intercalated between clay layers by cation exchange. An original combination between chemorheological and model-free kinetic analysis allows highlighting the influence of MMT on the overall polymerization pathway. The octadecyl ammonium cation (ODA) was also used as homogeneous acidic catalyst to highlight the specific role of this interlayer cation present in Org-MMT. Interestingly, FA/Org-MMT polymerizes more rapidly than FA/ODA but initiation of polymerization is slightly shifted to higher temperature due to initial intercalation between MMT layers. Then, the dual acidic character (Lewis + Brönsted) of Org-MMT leads to gelation at early stage of polymerization. The results clearly show that exfoliation of MMT layers increases the efficiency of collisions.

A Review on Epoxy and Polyester Based Polymer Concrete and Exploration of Polyfurfuryl Alcohol as Polymer Concrete

“…In a second stage, these linear oligomers were cross-linked into branched black materials and they were demonstrated by NMR experiments [72]. Recently, a greener and more sustainable catalytic route was proposed in order to replace hazardous acidic catalysts [41]. Organically modified montmorillonite (Org-MMT) and, in comparison, sodium MMT (Na-MMT) were used to evaluate the catalytic effect on the FA polymerization to PFA.…”

Biobased Epoxy Nanocomposites Derived from Lignin-Based Monomers

“…28 This catalytic effect of montmorillonite may come both from Bronsted acidity, due to dissociation of intercalated water molecules coordinated to cations, and Lewis acidity located in the octahedral sheets that can be efficiently promoted by cation-exchanged montmorillonite. 33 Furthermore, Figure 7, panel C shows an evident decrease in activation energy (from around 55 to 45 kJ/mol) as nanoclay content increases from 0 to 12 wt %, which highlights the catalytic role of nanoclay, as it indicates the catalytic impact of organic clay is stronger than the negative influence of the steric effect of the clay exfoliation. 34 3.4.2.…”

Curing of poly(furfuryl alcohol) resin catalyzed by a homologous series of dicarboxylic acid catalysts: Kinetics and pot life

“…7,18,19 It has been demonstrated 7,19 that the hydrogen atoms positioned on the methylene bridge between two furan rings play an important role in the color formation and are responsible for the crosslinking reaction with hydroxyl end groups of another chain. The condensation reaction of a methylol group with the C5 position of another furan ring, which causes dehydration.…”

“…The crosslinking of the linear oligomers, which leads to black-colored networks. 7,18,19 It has been demonstrated 7,19 that the hydrogen atoms positioned on the methylene bridge between two furan rings play an important role in the color formation and are responsible for the crosslinking reaction with hydroxyl end groups of another chain. The other suggested mechanism for PFA crosslinking is the Diels-Alder cycloaddition between the furan rings (diene) in oligomeric molecules and the conjugated dihydrofuranic sequences (dienophile).…”

“…The other suggested mechanism for PFA crosslinking is the Diels-Alder cycloaddition between the furan rings (diene) in oligomeric molecules and the conjugated dihydrofuranic sequences (dienophile). 7,18 Two major factors affecting the curing rate of PFA resins are the type and concentration of acid catalyst used. The application of a weak acid catalyst, such as acetic acid, leads to the incomplete curing of the resin even at temperatures higher than 100 8C.…”