466469 Modifying the Surface Properties of Wood Using ATRP Grafting Polymerization

Monday, November 14, 2016: 4:30 PM
Lombard (Hilton San Francisco Union Square)
Marta Vidiella del Blanco1,2, Ingo Burgert1,2 and Etienne Cabane1,2, (1)Wood Materials Science, Institute for Building Materials (IfB), ETH Zürich, Zürich, Switzerland, (2)Applied Wood Materials, EMPA – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland

Wood is a well-known bio-based material which can be used for a wide range of applications, with a major focus on its utilization as a building material. In order to profit from its natural properties and to develop smart and innovative materials, a variety of chemical modifications can be used. Cabane et al. have shown that wood can be modified by in-situ grafting of synthetic polymers enhancing the natural properties of wood and making it competitive with other available materials [1]. We recently extended the modification of wood through the grafting of fluorinated acrylates by surface-initiated ATRP (Fig 1A). ATRP is a living polymerization technique allowing for a better control over grafted polymer chain length. The polymer chains are grafted from the wood biopolymers through a two-step reaction. In the first step the ATRP initiator is grafted onto the wood surface (via esterification), and it is used in the second step to grow the polymer chains.

Several techniques were used to characterize the wood properties after the polymerization. Amongst others, the most outstanding results obtained were in regard to the wettability. Through the functionalization of wood with a fluorinated polymer, and following the examples of superhydrophobic surfaces found in nature, we have acquired a renewable material that is both superhydrophobic and oleophilic. The contact angles of water on the wood surface measured before and after modification increase drastically with values raising from 73º to 180 º (Fig 1B). This increase is both due to the chemical modification and the surface roughness acquired by the combination of the both the natural roughness of wood and the grafted polymer chains.

Moreover, quaternary amine acrylates were grafted onto the wood in order to further study the wettability given by the combination of the natural structure of wood and the chemical and physical properties of the polymer introduced. Both quaternary amines and fluorinated acrylates have been separately and successfully grafted into wood (Fig. 1C) offering different wettabilities (Fig 1D). In further work we would like to extend the methods used to copolymerize fluorinated and quaternary amine acrylates, combining the properties of both polymers. By this copolymerization it would be possible to obtain a material that is both hydrophilic and oleophobic [2]. This new material could be used to extract the oil present in contaminated water resources.

Fig. 1: A) Wood modification scheme; B) Contact angle measurements of water on the wood surface; C) FTIR spectra; D) Wettability of wood with various liquids.

[1].  E. Cabane, T. Keplinger, V. Merk, P. Hass, I. Burgert, ChemSusChem 2014, 7, 1020-1025.

[2]. P. Brown, O. Atkinson, J. Badyal, ACS Applied Materials & Interfaces 2014, 6, 7504-7511.

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