Supporting Information Interaction mechanisms between guaiacols and lignin: the vinyl bond makes the difference V. Daniela Barrera-García 1,2,‡ , David Chassagne 1,2 , Christian Paulin 3 , Jésus Raya 4 , Jérôme Hirschinger 4 , Andrée Voilley 2 , Jean Pierre Bellat 3 and Régis D. Gougeon 1,2* Characterization of the lignin. The specific surface area of lignin has been determined by N 2 adsorption at 77 K using the BET method. The adsorption isotherm is of type II, which is representative of nonporous or macroporous solid. 1 The measured specific surface area is 38 + 1 m 2 .g -1 for this lignin sample, comparable to values reported in the literature. 2 As shown by Faix, 3 lignin can also be characterized by FTIR spectroscopy. The spectrum of our lignin (Figure 2) displays the classical features of hardwood lignin of the GS type, with a characteristic most intense absorption at ~ 1124 cm -1 assigned to aromatic C-H in plane deformation in G and S units. A detailed analysis of the fingerprint region can further classify our lignin among four possible types and thus provide a semi-quantitative description of the G/S ratio and methoxy groups. 3 In particular, the higher band at ~ 1328 cm -1 (C-O vibration of S rings) than the one at ~ 1268 cm -1 (shoulder, C-O of G rings), the pronounced band at ~ 835 cm -1 and