Wood impervious oil-grafted tannin foams
PI : Christine Gerardin —
Laboratoire d’Études et de Recherche sur le Matériau Bois (LERMAB)
Co-applicants: Eric Masson (CrittBOIS), Alain Celzard (Institute Jean Lamour)
Collaboration : Antonio Pizzi (LERMAB), Hubert Chapuis (LERMAB)
Context — For several years, new biosourced cellular materials have been in development through the use of condensed tannins extracted from the bark of trees. This type of foam is among the most innovative foams proposed in recent years. In particular, Tannin-furanic foams, based on the co-reaction of bark-derived condensed tannins and thermosets furanic polymers, have been prepared, characterized and extensively studied in the LERMAB laboratory. The low thermal conductivity, the self-extinguishing capacity and high fire resistance of these foams has allowed us to envisage the development of several industrial uses with a number of companies in very different fields of application, and there has been considerable interest. Unfortunately, one of the characteristics of these foams is the absorption of water in the foam itself. Another problematic feature of these foams is their rather sensitive surface friability which poses a definite drawback to some of their utilizations.
Objectives —This project aims to graft one or several hydrophobic chains on polyphenols and to use these hydrophobic polyphenols in the previously developed formulations of tannin-furanic foams. The long, water-repellant fatty chains grafted onto the polyphenol will improve water repellency of the basic tannin materials and will further improve water resistance of these materials.
Approaches — Two approaches are conceivable, namely the use of oil based pre-grafted tannins for the preparation of the foams or even, while perhaps more difficult, the grafting of hydrophobic side chains on the hydroxyl groups in existing foams.
Expected results and impacts — This subject is, above all ,for an applied purpose and should allow for the production of innovative renewable materials. This study is also fundamental as it will allow us to study the chemical reactivity of tannins and of polyphenol in general.