A Multi-Technique Thorough Synthesis and Characterization of Tannin-Furanic Foams, a Sustainable Biobased Alternative to Foams Derived from Fossil Fuel-Based Chemicals

Aiming on sustainability options, materials that are discarded from the industry, and given a second life, are highly desirable. Condensed tannins, extracted from the saw-mill residue bark, constitute the starting point to create tannin-furanic foams, a rigid biobased material that could be a sustainable alternative to those derived from fossil fuel-based chemicals. With the objective of developing novel foam production strategies, three different tannin-furanic foams, namely mechanical, sulfuric and nitric, were thoroughly chemically characterized, and their morphological and macroscopic properties were compared with those of commercial plastic foams made of polystyrene and of polyethylene terephthalate. Understanding the influence of the foaming method on the foam properties is of utmost importance when aiming to substitute existing, well-established products. The chemical characterization was performed by using NMR, FTIR and UV Raman, assisted by DFT quantum mechanics simulations. The morphological characterization was done by FTIR imaging and X-ray micro-Tomography. Our studies demonstrated nitric tannin-furanic foams as the nearest approach as an insulating material, while mechanical tannin-furanic foam is more appropriate as a tough material, bio-based tannin-furanic foams therefore indeed appearing a feasible green alternative to plastic foams derived from fossil fuel-based chemicals.