Preparation and investigation of properties of polybenzimidazole and polybenzoxazole based nanofibers

In this thesis, it is aimed to obtain polybenzimidazole (PBI) and polybenzoxazole (PBO) nanofibers by using different solvents and different hybrid polymers capable of electrospinning. The most suitable solvent pair and hybrid polymer were selected by examining some properties of the obtained nanofibers. The PBI and PBO polymers used in the electrospin treatment are obtained from the polycondensation reaction of hydroxamoyl chlorides [terephthalohydroxamoyl chloride, 4,4'-bis (phenylhydroxamoyl chloride), 4,4'-bis (phenyl hydroxamoyl chloride) ether] with aromatic amine [3,3'-diaminobenzidine and of 3,3'-dihydroxybenzidine] monomers. The PBI and PBO electrospin solutions were prepared using DMF, THF and Ac solvents. In addition, PVP, PS and PVDF polymers which are electrospinable polymers were used as hybrid polymers. Solvent effect of nanofibers obtained with the prepared solutions on iec and surface contact angle values were investigated. PVDF hybrid nanofibers prepared with a 3/1 solution of DMF / Ac solvent pair were found to have the best ion and surface contact angle. PBONF3 nanofiber was identified as the best nanofibers with a surface contact angle of 143,1º. The highest ion exchange capacity was found to be 2.5 mmol / g for PBINF2 nanofibers. The effect of solvent selection on SEM fiber diameter was investigated. PBINF and PBONF hybrid structures are found fiber diameter distribution between 150-450 nm from fiber diameter distribution graphs. Water uptake capacities could not be calculated due to the biodegradability of PVP in nanofibers prepared with PVP. Nanofibers prepared with PVDF uptake water in the range of 14.7 % - 38.46 %. Characterization of nanofibers was determined by FT-IR analysis. TGA analysis was performed to determine the thermal strength and percentage content of the nanofibers by mass. According to TGA analysis, first decomposition temperatures of nanofibers were determined between 400-450 ºC. The relationship between volume fraction and water uptake capacity was investigated. PBONF3 was determined to be the best hydrophobic nanofiber with a volume fraction of 19% and a water uptake capacity of 14.7%. In addition, the sound absorption test was performed for all nanofibers and it was observed that they had high sound absorption properties. As a result, in this study, lightweight, high ion exchange capacity, thermal strength, hydrophobic character and sound damping properties of nanofiber materials were obtained.