Figure 2.

Preparation of stable CMC networks by the combination of physical and chemical crosslinking. (a) Chemical structure of the CMC repetitive unit; two CMCs with DS = 0.7 were used in this work, i.e. CMC-L and CMC-H. (b) CMCs with DS ≤ 1 may form physical crosslinks in concentrated solutions, due to the establishment of hydrophobic associations among the unsubstituted cellulose blocks; based on its higher molecular weight and higher thixotropy, CMC-H is expected to form a more entangled structure than CMC-L (at fixed concentration). (c) Chemical structure of CA and (d) esterification reaction with the CMC; the reaction is activated by heat and occurs upon preliminary casting and drying of a CA/CMC solution. (e) Presence of both physical and chemical crosslinks in the final CMC network.