COMPLEXES OF STARCH WITH TELECHELIC POLY(EPSILON-CAPROLACTONE) PHOSPHATE

The interaction of starch with poly(epsilon-caprolactone) having end-linked phosphate groups (PCL phosphate) was studied in order to determine if aliphatic polyesters could form inclusion complexes with starch similar to those formed from amylose and fatty acids. Normal cornstarch co-jet cooked with aqueous PCL phosphate solutions formed highly viscous gels on cooling, whereas jet-cooked starch solutions had low viscosities. Solutions of waxy maize starch had low viscosities after jet cooking either with or without PCL phosphate, while high amylose starch formed gels with or without PCL phosphate. Essentially all amylose precipitated from a dilute solution upon addition of PCL phosphate solution. After extraction with a solvent for the PCL phosphate, about 0.l g PCL phosphate remained bound per g of amylose. X-ray diffraction and CP/MAS C-13 NMR studies showed that the PCL phosphate/amylose complexes adopt a semi-crystalline, V-type helical inclusion structure.