Aliphatic polyester-grafted starch composites by in situ

Catalyzed Ring-Opening Polymerization (ROP) of lactones, such as c-caprolactone and ii-vnlerolactone. ha\ been investigated for preparing aliphatic polycsrer-grafted corn starch compositions. The polynieri7ntion has been carried out either i n bulk (without solvent) or in I0 wtQ grunular starch i n toluene \uspension. aftcr adequate activation of thc starch wrface arnylosc/amylopectin hydroxyl groups into aluminum alkoxides. This activation has been done by it1 si/rr reaction with triethylaltiininuin and has proved to be very effective in promoting fast ROP and nlw covalent grafting o f the polyestcr chains onto thc starch xurfacc. Drying of the starch granules constitutes a key-step of the p r o p o d process. The actual lixation of the initiator onto the \tarch wrface has been chccked by XPS analysis whereas good adhesion between the two cornponenls has been evidenced by SEM observations. Growth of the polyester chains on the starch granules has bccn followed by thc increase of thc inean diameter o f the 'encapsulated' granulcs a\ attested by laser scattering granulometry. Koywotdv: Starch: aliphatic polycstei-s: poly(c-caprolactone): ringopening polymrriz;rtinn. composites.