Electrospinning is an effective method in preparing polymeric nanofibrous drug delivery systems (DDSs) for topical wound healing and skin burn therapy applications. The aim of the present study was to investigate a new synthetic graft copolymer (Soluplus) as a hydrophilic carrier polymer in electrospinning of nanofibrous DDSs. Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG)) was applied in the nonwoven nanomats loaded with piroxicam (PRX) as a poorly water-soluble drug. Raman spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and scanning electron microscopy (SEM) were used in the physical characterization of nanofibrous DDSs. According to the SEM results, the drug-loaded PCL-PVAc-PEG nanofibers were circular in cross-section with an average diameter ranging from 500 nm up to 2 µm. Electrospinning stabilized the amorphous state of PRX. In addition, consistent and sustained-release profile was achieved with the present nanofibrous DDSs at the physiologically relevant temperature and pH applicable in wound healing therapy. In conclusion, electrospinning can be used to prepare nanofibrous DDSs of PCL-PVAc-PEG graft copolymer (Soluplus) and to stabilize the amorphous state of a poorly water-soluble PRX. The use of this synthetic graft copolymer can open new options to formulate nanofibrous DDSs for wound healing.

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Thermal stability of intrinsic polyaniline (PAn) and its derivatives is studied with T G and DSC under different atmospheres. Common polyaniline is fractionated into five fractions with solvent dissolution. Under nitrogen atmosphere, the onset decomposition temperature increases from 232'C for T H F soluble-acetone insoluble fraction to 430C for concentrated H,SO, soluble-NMP insoluble fraction , but the weight loss a t 500'C has no distinctive difference among the fractions, indicating that both step and random decomposition take place in the thermal procedure. Increase of molecular weight of poly (0-toluidine) (POT) or poly (0anisidine 1 (PAS) can also improve their thermal stability, but the steric repulsion between methyl or methoxy groups reduces the interchain interaction in POT or PAS , thus lowers their thermal stability. TG curve of POT in air exhibits apparent weight up-take at 190°C-230°C (as high as 6wt%) due to the thermal oxidation of methyl on aromatic ring into carboxy acid. The degree of weight up-take depends greatly on backbone defect and methyl group content. Under nitrogen atmosphere , cross-linking reaction happens on POT at 22O'C -250'C instead of weight up-take. 342