Cellulose as a Source of Water Dispersible Renewable Film-Forming Materials

Cellulose is found to be a good source of waterborne film-forming materials when modified with the correct type and level of functional groups. The modification of cellulose to incorporate high levels of levulinic functionality and other C 2 –C 6 alkyl esters is reported for the first time. The levulinyl-functionalized cellulose is readily modified to produce oxime or acylhydrazone derivatives, which is particularly useful to fine-tune the physical characteristics of the cellulose ester. This includes the glass transition temperature of the cellulose esters, their ability to produce fine uniform colloidal particles in aqueous media and ultimately provide the principle film-forming component of an architectural coating. The process has been demonstrated at the 500 g level suggesting ready scalability. Lewis acids and Lewis acid-assisted Brønsted acids are employed for the first time in such chemistry, and together with sulfur-based Brønsted acids are all found to be effective catalysts for the esterification of cellulose to produce mixed ester systems. The Lewis acid catalysts demonstrate exceptional activity and produce high molecular weight cellulose derivatives.