INCLUSION COMPOUND FORMED BETWEEN POLY(L-LACTIC ACID) AND UREA

We have successfully incorporated poly(L-lactic acid) (PLLA) into the narrow channels of its inclusion compound (IC) with urea(U). PLLA-U-IC was obtained by cocrystallization following the addition of a warm, saturated solution of urea in methanol to a warm, dilute chloroform solution df PLLA. Calorimetric observations (DSC) revealed that PLLA-U-IC melted at 137 degrees C with an approximate enthalpy of 41 cal/g. Wide-angle X-ray diffractograms of PLLA-U-IC powders and FTIR spectra of their KBr pellets both strongly point to the formation of a hexagonal PLLA-U-IC structure very similar to that observed for the U-IC's formed with n-alkanes and polyethylene. High-resolution solid-state C-13 NMR observations of pure PLLA and PLLA-U-IC reflect the differences between the PLLA. conformations and packing environments found in the ordered, solid bulk and U-IC samples.