Title
Novel cellulose and starch-based materials
Authors
B. VOLKERT A. LEHMANN and K. HETTRICH

Received October 14, 2013
Published Volume 48 Issue 5-6 May-June
Keywords cellulose carbamate, N-methylmorpholine-N-oxide monohydrate (NMMNO*H₂O), homogeneous synthesis, cellulose sulfate, microencapsulation, nanocellulose, thermoplastic starch mixed esters

Abstract
The experiences on cellulose research in our region, first in Teltow and later in Potsdam-Golm, have extended over many years since the 1920s with the foundation of the Vereinigte Glanzstoff-Fabriken in Teltow-Seehof, followed by the Institut für Faserforschung and the Institut für Polymerforschung of the Academy of Sciences of the GDR, up to the Fraunhofer Institute for Applied Polymer Research IAP, which is now situated in Potsdam-Golm. While the original fiber production in Teltow-Seehof was based on the viscose process, which is still the dominating process for producing man-made cellulose fibers, alternative ecologically friendly procedures have been developed in the course of the years. One of these developments concerns the so called CarbaCell process, whereby the chemical modification of cellulose with urea (instead of carbon disulphide in the viscose process) leads to cellulose carbamate, which can be spun and regenerated. Another alternative is the direct solution procedure in N-methylmorpholine-N-oxide monohydrate (NMMNO*H2O). This non-derivatizing solvent for cellulose can also be used for several homogeneous chemical reactions, whereby in comparison with the classical heterogeneous slurry processes, a completely different distribution of substituents in the anhydroglucose unit and also along the polymer chain is achieved. The substitution pattern has a high influence on the properties of the products, especially on the solution behavior. Also, anorganic cellulose esters like phosphates and sulfates can be synthesized regioselectively at positions C6 or C2/C3. Especially the cellulose sulfate with substitutions at position C6 is a suitable material for the micro-encapsulation of living cells for clinical applications.
Slightly substituted cellulose derivatives are also the starting point for the formation of nanocellulose, which is prepared as a clear and opalescent dispersion after a mechanical treatment.
Another subject matter is the development of starch-based materials. Starting from thermoplastic starch by adding a plasticizer, highly substituted starch esters are developed, which show mechanical properties like petrochemical-based thermoplastic materials.
A short overview of some research activities on the topics of cellulose and starch at the Fraunhofer Institute for Applied Polymer Research IAP over the last 20 years is presented.