We have demonstrated the fabrication of double walled microspheres from a mixture of two polymers - poly(L-lactide) (PLLA) and poly(L-lactide-co-glycolide) 50:50 (PLGA 50:50) resulting in a core of polymer A rich phase and a shell of polymer B rich phase(12). It is important to obtain a composition profile of these spheres so that we can evaluate the orientation of the two phases and eventually manipualte these phases to design improved double walled systems. So far it has been a difficult task due to inherent problems with determining the composition of the spheres but with the current technique described in this paper some of the problems have been overcome. In addition PLLA and PLGA are chemically so similar that it is not always easy to identify and separate the different peaks in characterization techniques such as the Fourier Transform infrared spectroscopy. Therefore we had to resort to the differential scanning calorimetry to quantify the amounts of PLLA and PLGA 50:50 in our double walled spheres.
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