Low Fluorinated Oligoamides for Use as Wood Protective Coating

New highly hydrophobic fluorinated oligoamides were synthesized and studied as materials for the protection of non-varnishable wooden artifacts. The new oligoamides were designedto achieve the best performance (including high chemical affinity to the wood material) and thelowest environmental impact. In order to minimize the risk of bioaccumulation, short perfluoroalkyl side chains were reacted with oligoethylene L-tartaramide (ET), oligoethylene adipamide-Ltartaramide (ETA), oligoethylene succinamide-L-tartaramide (EST), oligoethylene succinamide (ES),and oligodiethylenetriamino-L-tartaramide (DT). Favorable reaction conditions were also adopted toobtain low molecular weight compounds characterized by non-film-forming properties and solubilityor dispersibility in environmentally friendly organic solvents. Their behavior in terms of modificationof the wood surface characteristics, such as wettability, moisture absorption, and color, was analyzedusing a specific diagnostic protocol to rapidly obtain preliminary, but reliable, results for optimizinga future synthesis of new and tailored protectives. The influence of different monomer units on thereactivity, solubility, and hydrophobic properties of different oligoamides was compared showingESF (contact angle 138.2o) and DF (132.2o) as the most effective products. The study of stability tophotochemical degradation confirms ESF as promising protective agents for artefacts of historical andartistic interest in place of long-chain perfluoroalkyl substances (PFAS), products currently subject torestrictions on use.