Influence on the structure and the molecular mobility of cellulose–diamine complexes studied by a multiscale experimental approach

In this paper, the influence of diamines on the intrinsic structure and molecular mobility of cellulosic complexes is discussed. Cellulose was pre-swollen by ethylenediamine then put in contact with a series of aliphatic diamines at a stoechiometric ratio. These materials were then characterized by Wide Angle X-Ray diffraction (WAXS) and solid-state \(^{13}C\) ${}^{13}C$ NMR spectroscopy. It was observed by WAXS that diamines are able to swell cellulose along the (010) crystallographic plane and are able to modify unit cell angle \(\gamma \) $\gamma$ of cellulose monoclinic structure. Moreover according to their periodicity, ordered- or disordered-phases structures were identified in such cellulosic complexes by Cross Polarization - Magic Angle Spinning (CP-MAS) \(^{13}C\) ${}^{13}C$ NMR spectroscpy. Two-dimensional Wide-line Separation (2D WISE) and \(T_1\) $T_1$ relaxation time \(^{13}C\) ${}^{13}C$ NMR spectroscopy experiments showed that complexes do exhibit molecular motions between 23 and 90 \(^{\circ }\) ${}^{\circ }$ C. Modulated Differential Scanning Calorymetry (MDSC) further showed the presence of two glass transition temperatures \(T_g\) $T_g$ , which were attributed, in combination with the \(^{13}C\) ${}^{13}C$ NMR spectroscopy observations through a multiscale approach, to relaxation motions internal to the diamines chemical structure and to the motion of cellulose–diamine planes respectively.