Improving photostability of poly(1,3,4-oxadiazole)s fiber

Poly(1,3,4-oxadiazole)s (POD) was a kind of thermally stable fiber. However, its photostability was not good enough in practical application. Although some methods, such as synthetic modification or treatment by using polyhedral oligomeric silsesquioxane, were used to improve photostability of POD, the procedure was too complicated or costly. In this work, the photostability of POD fiber was improved by adhered iron trihydroxide (Fe(OH)₃) through coordination bond, which was a relatively simple method. The ferric chloride (FeCl₃) was easily adhered to surface of POD fiber by dipping method and then Fe(OH)₃ formed by treatment with sodium hydroxide (NaOH) solution. The existence of Fe(OH)₃ and formation mechanism were proved by XPS, SEM-EDS and FTIR, and the homogeneousness was observed by SEM. Results of XPS and FTIR measurements suggested that the adherence driving force was coordination bond. SEM characterization illustrated that the adherence was quite homogenous. The ability of UV-absorption of Fe(OH)₃, which was confirmed by UV-spectra, could protect poly(1,3,4-oxadiazole)s fiber from photodegradation. The effect of protection was testified by mechanical testing. The results indicated that the Fe(OH)₃ can improve photostability of poly(1,3,4-oxadiazole)s fiber effectively.