  As we passed the 20th anniversary of the publication of the 12 principles of
green chemistry, the sustainable modification of cellulose, being the most
abundant biobased polymer, is certainly worth considering. Many researchers
work on an efficient valorization of this renewable resource due to its
manifold and promising application possibilities, but very often the use of
non-sustainable approaches (i.e., solvents, reactants and modification
approaches) only addresses the renewability aspect of cellulose, while
neglecting most or all of the other principles of green chemistry. In this
review, we have employed the use of E-factors together with basic toxicity
information to compare between various approaches for homogeneous cellulose
modification. This approach, though simple and certainly not overarching, can
provide a quick and useful first sustainability assessment. Therefore, in order
to achieve a truly sustainable modification of cellulose, its renewability
combined with mild and efficient reaction protocols is crucial in order to
obtain sustainable materials that are capable of reducing the overall negative
impact of today's fossil-based polymeric materials.
