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Development of hot-melt extrusion as a novel technique for the ...

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atom <strong>as</strong> NH + 4 . This observed N 1s peak at BE= ~402.80 eV is in good agreement with <strong>the</strong>previously observed protonation <strong>of</strong> amide group by Beamson and Briggs [33] . The BE peak at~402.80 eV (higher than typically observed <strong>for</strong> amines BE= ~399 eV - 400.5 eV and muchmore <strong>for</strong> –NH + +2 group) <strong>for</strong> N1s is an indication <strong>of</strong> C-O-NH 2 structure where<strong>as</strong> <strong>the</strong> O atompeak at ~534.40 eV shows <strong>the</strong> same [18, 20] . These results strongly indicate an interactionbetween <strong>the</strong> amide group <strong>of</strong> <strong>the</strong> API and ester/carboxyl group <strong>of</strong> <strong>the</strong> polymer (L100) through<strong>the</strong> available H-interactions or hydrogen bridges (Fig. 7.5c).Fig. 7.5c: N 1s BE peaks <strong>of</strong> PRP and extruded <strong>for</strong>mulations.Similarly, N 1s peaks from PRP/L100-55 and DPD/L100-55 also complement <strong>the</strong>observations from PRP/L100 and DPD/L100 <strong>for</strong>mulations. The N (1s) energy <strong>of</strong> ~402.9 eVin DPD/L100 <strong>for</strong>mulation suggests protonation <strong>of</strong> <strong>the</strong> amide group <strong>as</strong> observed <strong>for</strong>a<strong>for</strong>ementioned PRP/L100 <strong>for</strong>mulation. The BE peak at ~402.90 eV (Fig. 7.5d) <strong>for</strong> N 1s is an+indication <strong>of</strong> C-O-NH 2 structure with longer peak shift than that <strong>of</strong> PRP/L100. As be<strong>for</strong>e, weconcluded that a strong interaction between <strong>the</strong> amide group <strong>of</strong> API and ester/carboxyl group<strong>of</strong> polymer through <strong>the</strong> available H-interactions h<strong>as</strong> taken place.145 | P a g e

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