Starch Graft Copolymers: Novel Applications in Industry

Starch, which is a natural carbohydrate biopolymer, has been the subject of academic and industrial studies for many decades, basically due to its low cost, biodegradability and versatility of use. Chemical modification of starch by grafting various monomers onto it imparts increased hydrophilicity, hydrophobicity or polyelectrolyte nature to starch depending on the reagent and conditions used. The starch graft copolymers are synthesized by the free radical initiated reaction of starch with acrylic monomers in presence of a free radical initiator such as ceric ammonium nitrate. High viscosity, thermal stability, biodegradability, good film forming properties and water absorption capacity are some of the properties shown by the graft copolymers of starch. Graft copolymers find various applications in industry as flocculants, waste water treatment and heavy metal ion removal, for sizing cotton, as mulch films, in oil drilling, as biodegradable polymers and in superabsorbents. Starch graft copolymers are also gaining increasing importance in the manufacture of molded plastics, ion-exchange resins, plastic films and in cosmetics. Non-biodegradable plastic waste is an ecological threat. Use of starch as an extender and replacement of synthetic polymers-based hydrogels is currently an active research area. Incorporation of starch into other synthetic polymers not only reduces our dependence on petrochemical derived monomers but also provides materials in which the starch portion can biodegrade rapidly in the environment. (C) Koninklijke Brill NV, Leiden, 2010