Polymerization of acrylated epoxidized soybean oil with phenol furfural resins via repeated forward and retro diels–alder reactions

Abstract

In this work, the Diels-Alder reaction between the acrylate groups of acrylated epoxidized soybean oil and the furan rings of p-tertiary butyl phenol furfural resin (TBPF) is described. The reaction was carried out at 110 C in presence of FeCl 3 catalyst, and tough polymers were obtained in 1 h. Surprisingly, samples that were heated and cooled 5, 10, and 20 times to 140 C and room temperature had better mechanical properties than samples that were kept at 140 C for the same total duration. This unexpected behavior is attributed to a series of forward and retro Diels-Alder reactions between the functional groups. To prove this hypothesis, a model reaction between TBPF and n-butyl acrylate was studied. At 100 C, 1 H-nuclear magnetic resonance signals of the furan ring protons disappeared, only to reappear at 140 C. Thermogravimetric analysis of the adduct showed a weight loss at 140-150 C, which was in quantitative agreement with the amount of butyl acrylate. Infrared analysis showed that furan rings were not completely consumed by extended heating at 110 C. After five heating and cooling cycles of much shorter duration at 140 C, the furan absorption in the infrared disappeared. The storage modulus of acrylated epoxidized soybean oil-TBPF samples after 20 heating cycles was 1.15 GPa.

A Combined Experimental–Theoretical Study on Diels‐Alder Reaction with Bio‐Based Furfural: Towards Renewable Aromatics

“…For instance, alkyl phenols can be produced by the catalytic lignin-first depolymerization process [3] or from tannins present in lignocellulosic biomass. [4] Aromatics can be also produced from hemicellulose or cellulose through the furfural [5][6][7][8][9][10][11][12][13] or 5-hydroxymethylfurfural platform, [14,15] using a Diels-Alder (DA) / aromatization sequence. A similar strategy has been reported, using pinacol [16] or limonene as other bio-based platforms.…”

“…[6,7] For instance, Hubert reported the synthesis of toluene and benzene by co-feeding ethylene or propylene with furfural at 450-600°C in the presence of ZSM-5, with in situ decarbonylation of furfural. [6a] Alternatively, to preserve the chemical functionality of furfural while decreasing the HOMO-LUMO gap, furfural can be derivatized to amines, [8] acetals, [9] alcohols, [10] phenolic-type resins [11] or amides, [12] making the DA reaction thermodynamically favorable This strategy was employed to synthesize furfuralderived polymers which can be depolymerized via a retro-DA reaction at the end of life. The aromatization of these furfural-FULL PAPER 2 derived cycloadducts has been investigated only sporadically.…”