Poly(Vinyl Alcohol) Chemical-Dehydration to Polyacetylene By Absolute Sulfuric Acid

Recently, polyacetylene (PA) is receiving a renewed scientific attention because of its unique properties potentially useful also for non-electrical applications (e.g., hydrogen storage, drug delivery, adsorbent of organic compounds in aqueous systems, gas and liquid separation, oxygen absorbent in gas analysis, etc.). Poly(vinyl alcohol) (PVOH) is a very common type of polymer, widely exploited in different technological areas, and it can be used as a precursor for the PA synthesis. Here, a new scheme for a large-scale chemical synthesis of PA, based on a simple and low-cost PVOH dehydration reaction by absolute sulfuric acid, has been developed. In this process, PVOH, shaped in form of film, is dipped in absolute sulfuric acid (i.e., H2SO4 at 95-97%) and, after complete chemical-dehydration at room temperature, it is mechanically removed from the liquid phase by using a plastic sieve. This reaction leads to a complete PVOH film conversion to PA as it has been proved by infrared spectroscopy (ATR-mode). Indeed, the ATR spectrum of the reaction product included all characteristic absorption bands of PA. To the best of our knowledge, this very easy and effective PA synthesis method based on the PVOH chemical-dehydration reaction by absolute sulfuric acid has never been described in the literature.