Physicochemical evaluation of polyvinyl alcohol films crosslinked with saturated and unsaturated dicarboxylic acids: A comparative study

Abstract In this study, crosslinked films of polyvinyl alcohol (PVA) were prepared using two dicarboxylic acids: saturated succinic acid (SA) and unsaturated maleic acid (MAL) as crosslinkers. The crosslinking capabilities of these acids were compared through physical, chemical, mechanical, morphological, thermal analysis, and swelling measurements to investigate their impact on the physicochemical properties of the resulting films. Attenuated total reflectance fourier transform infrared spectroscopy (FTIR) confirmed the occurrence of an esterification reaction between PVA and the dicarboxylic acids. Based on the degree of crosslinking and thermal properties, it was noted that the crosslinking achieved with maleic acid is more effective for PVA compared with succinic acid. The crosslinking degree of PVA‐MAL was determined to be 6.47 times higher than that of the PVA‐SA film. In terms of thermal stability, the decomposition temperature for crosslinked PVA‐MAL was measured at 365.57°C, whereas PVA‐SA exhibited a slightly lower decomposition temperature of 362.58°C. The findings indicate that the PVA‐MAL film displays lower crystallinity and a higher contact angle (80.60°) in contrast to PVA‐SA (76.0°) and PVA (30.4°). Atomic force microscopy analysis indicated that the PVA‐SA film exhibited more surface roughness compared with the smoother PVA‐MAL film. Also, crosslinked films displayed enhanced elasticity and resilience in comparison with neat PVA, which may be due to the difference in crosslinking density, disruption in intermolecular hydrogen bonding due to crosslinking, and incorporation of flexible crosslinkers. Highlights PVA was crosslinked using SA and MAL. Unsaturated MAL exhibited superior crosslinking density over saturated SA. PVA‐SA film exhibited a porous surface compared to PVA‐MAL film. PVA crosslinked with unsaturated MAL showed higher thermal stability than SA. Both the films showed enhanced elasticity and resilience compared with neat PVA.