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    Diethoxy-azobis(pyridinium) salt as photoinitiator for cationic polymerization
    (Wiley-V C H Verlag Gmbh, 2008) Durmaz, Yasemin Yuksel; Zaim, Oemer; Yagci, Yusuf
    N,N'-diethoxy-4,4'-azobis(pyridinium) hexafluorophosphate (DEAP) has been synthesized by alkylation of the corresponding N-oxide and characterized. DEAP exhibits UV induced cis-trans isomerization with absorptions at around lambda = 459 and 360 nm, respectively. The ability of the DEAP ion to act as a photoinitiator for the cationic polymerization of cyclohexene oxide and N-vinylcarbazole is demonstrated. The initiation step involves the decay of the excited state of the trans form of the salt with homolytic bond rupture of the nitrogen-oxygen bond. Its potential use as a photoinitiator for free radical polymerization is also demonstrated using methyl methacrylate monomer as the example.
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    A new strategy for direct solution electrospinning of phosphorylated poly (vinyl chloride)/polyethyleneimine blend in alcohol media
    (Pergamon-Elsevier Science Ltd, 2023) Altinkok, Cagatay; Sagdic, Gokhan; Daglar, Ozgun; Ayra, Merve Ercan; Durmaz, Yasemin Yuksel; Durmaz, Hakan; Acik, Gokhan
    Phosphorylated poly(vinyl chloride) (PPVC)/polyethyleneimine (PEI)-based nanofibers were produced via electrospinning in their blended solutions for the first time. For this purpose, PVC was partially converted into PVC-N3 and the PVC-N3 is then reacted with bis(diethoxyphosphoryl) acetylene (BDPA) via metal-free azide--alkyne 1,3-dipolar cycloaddition reaction to achieve the alcohol-soluble PPVC. PPVC and PEI solutions at certain concentrations prepared in methanol were electrospun from a single syringe at 90/10 and 85/15 vol ratios without phase separation. The accuracy of the modifications conducted on PVC was proven by Fourier-transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR) spectros-copies and gel permeation chromatography (GPC), respectively. The achieved nanofibers and their intermediates were characterized by scanning electron microscope (SEM), water contact angle (WCA) measurement, ther-mogravimetric (TGA) and differential scanning calorimetry (DSC) analyses.The blood interaction of PPVC-PEI was evaluated through hemolysis and platelet activation assay, since most of the biomedical applications of PVC derivatives have close contact with blood. The results showed that PPVC-PEI nanofibers provide a safer surface for platelet with lower hemolytic activity compared to PPVC nanofibers. Therefore, PPVC-PEI-based electrospun nanofibers obtained by such an effective strategy exhibited a promising perspective for scientists in various biomedical purposes.