Development of Water Repellent, Non-Friable Tannin-Furanic-Fatty Acids Biofoams

Abstract

Tannin-furanic foams were prepared with a good yield using the addition of relatively small proportions of a polyflavonoid tannin extract esterified with either palmitic acid, oleic acid, or lauric acid by its reaction with palmitoyl chloride, oleyl chloride, or lauryl chloride. FTIR analysis allowed us to ascertain the esterification of the tannin, and MALDI-TOF analysis allowed us to identify a number of multi-esterified flavonoid oligomers as well as some linked to residual carbohydrates related to the equally esterified tannin. These foams presented a markedly decreased surface friability or no friability at all, and at densities lower than the standard foam they were compared to. Equally, these experimental foams presented a much-improved water repellence, as indicated by their initial wetting angle, its small variation over time, and its stabilization at a high wetting angle value, while the wetting angle of the standard foam control went to zero very rapidly. This conclusion was supported by the calculation of the total surface energy of their surfaces as well as of their dispersive and polar components.

An Investigation into the Relationship between Density and Pulverization Ratio for Tannin-Furanic Foam

“…Some research groups focused their works on finding out a way to reduce the phenomenon of high pulverization ratio in the case of TF [9,10]. Initially, starting with internal cross-linking, a cellular/nonporous TF was prepared via the addition of extra biomass [11].…”

“…One of the most intuitive manifestations is that the pulverization ratio for the modified TF was reduced efficiently, but inevitably the density of TF was increased in some formulations. In addition, vegetable oils were considered, and a significant reduction in the dropout of tannin-based foams could be achieved by the addition of palm oil [10,15]. Another option was to reconsider TF from a structural point of view and design the terminal foam product.…”