Cellulose nanofiber (MFC) reinforced starch-based foams, prepared by the freezing/freeze-drying route, are very interesting porous materials due to the strong MFC reinforcement of the cell wall itself. However, in order to fully realize the potential of these nanocomposite biofoams, both cell wall composition and cell structure must be controlled. The effect of starch–MFC–water suspension composition, together with preparation temperature (−27, −78, and −196 °C) on the foam cell structure is investigated. NMR-analysis of bound water content, DSC and freezing experiments in combination with freeze-drying experiments and FE-SEM microscopy are used to determine a suitable freeze-drying temperature. The freeze-drying temperature is critical in order to avoid cell structure collapse, as found from FE-SEM studies. By varying the cell-wall composition and preparation temperature, the foam morphology can be manipulated. The connection between cell size and starch content is considered to depend on the inherent properties of starch and a mechanism for ice crystal formation is suggested. Based on improved preparation conditions, foams with mixed open and closed cell structures and as much as 70 wt% MFC in the cell wall are created successfully.

The molecular self-diffusion coefficients in nematic and smectic-$A$ thermotropic liquid crystals are measured using stimulated-echo-type ${}^2\mathrm{H}$ and ${}^1\mathrm{H}$ pulse-field-gradient spin-echo nuclear magnetic resonance (PGSE NMR) combined with multiple-pulse dipolar decoupling and slice selection. The temperature dependence of the principal components of the diffusion tensor in the nematic phase follows a simple Arrhenius relationship except in the region of nematic-isotropic phase transition where it reflects, merely, the decrease of the molecular orientational order. The average of the principal diffusion coefficients in the isotropic-nematic phase transition region is close to the diffusion coefficient in the isotropic phase. At the nematic–smectic-$A$ phase transition the diffusion coefficients change continuously. The results in nematic phase are best described in terms of the affine transformation model for diffusion in nematics formed by hard ellipsoids. In the smectic-$A$ phase the data are interpreted using a modified model for diffusion in presence of a periodic potential along the director.