A study of non-bounded/bounded water and water mobility in different agar gels

Here we report the results of a systematic study aimed at exploring the water state and the types of water (i.e. bound non-freezable, bound freezable and freezable bulk-like) in agar hydrogels prepared from four different types of commercial agar powders. The influence of agar concentration on the water behaviour in the hydrogels was also investigated. The total water content, the identification and quantification of the different types of water was carried out by gravimetric, thermogravimetric and calorimetric analyses, while water mobility and localization in the gel network were investigated by unilateral 1H NMR. Moreover, 1H NMR depth profiles of agar gels applied on Noto stone specimens were collected to monitor the gel deformation due to water release and to evaluate the ability of the gel in controlling the water release into a porous material.