Carboxymethyl cellulose (CMC) has attracted considerable scientific attention, thanks to its enhanced water solubility and wide range of possible chemical reactions. In the present review, we attempt to summarize the current knowledge on chemical modifications of CMC, focusing specifically on the derivatization of its carboxyl functions, through “grafting onto” strategies. CMC derivatives, obtained by grafting of small molecules and/or polymers, can be engineered as peculiar assembled architectures (e.g., conjugates, nanoparticles, hydrogels), particularly suitable for the development of drug delivery systems or scaffolds for tissue engineering. The potential of the resulting CMC derivatives in biomedical applications is, therefore, discussed in detail.

The present work explores the possibility of chemically modifying carboxymethyl cellulose (CMC), a widely diffused commercial cellulose ether, by grafting of hydrophobic moieties. Amidation of CMC, at high temperature and in heterogeneous conditions, was selected as synthetic tool for grafting on CMC a panel of commercially available amines (bearing long aliphatic chains, alkyl aromatic and heteroaromatic groups, more or less spaced from the cellulose backbone). The reaction was successfully carried out in absence of solvents, catalysts and coupling agents, providing a promising and more sustainable alternative to conventional amidation procedures. Relationships between the chemical structure of the obtained CMC derivatives and their thermal properties were carefully studied, with a particular attention to the thermal behavior. Grafting of aromatic and heteroaromatic alkyl amines, presenting a linear alkyl chain between CMC backbone and a terminal bulky moiety, allowed for efficiently separating the polysaccharide chains, improving their mobility and resulting in a consequent lowering of the glass transition temperature (T_g). The T_g values obtained (90–147 °C) were found to be closely dependent on both the size of the aliphatic spacer, the structure of the aromatic ring and the extent of amidation.

The use of lignin as a filler for polymers to give composites provides both economic advantages and, in some cases, improved mechanical performance. The presence of lignin can also introduce certain advanced properties, including biodegradability, antimicrobial and antioxidant activity. Here we demonstrate that improved thermal insulation, thermal stability, and flame retardancy result when lignin is compounded with hydride-functionalized silicones to give elastomers and foams. In the absence of any additional inorganic flame retardant agent, the V-1 rating (UL-94) could be reached after chemical post-treatment of the materials with NH₃ vapor to remove excess SiH groups (which were identified as a culprit for excessive flammability). The fire resistance was further improved to the V-0 rating (UL-94) by applying additional thermal post-treatment at 220 °C in air. These foams also demonstrated low thermal conductivity, which were comparable with pure silicone foams of similar density. The improved thermal stability is attributed to flame retardant silica char, lignin repolymerization and char and the ability of lignin to scavenge radicals.