Examining fungal decomposition strategies in the development of environmentally friendly pressure-sensitive adhesives

Water-based pressure-sensitive adhesives (PSAs) are extensively utilized in various applications due to their affordability and convenience. Nonetheless, their production relies on acrylic monomers derived from oil, compromising their recyclability and biodegradability, which increased their environmental impact. To address this, hybrid acrylic polymers that incorporate acrylate-functionalized lactide-based macromonomers have been proposed. Our previous work evidenced the remarkable biodegradability of these hybrid PSAs in latex form when they were subjected to fungal treatments. This research specifically delves into the degradation of dried PSA films, a common application format in commercial settings, through the utilization of fungal consortia and solid-state fermentation. PSA degradation and deterioration were tracked through different approaches such as mass loss, infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and water contact angle measurements, and metabolomics. Our findings revealed that the choice of fungal species, carbon source, and substrate thickness significantly influenced biodegradation rates. Particularly noteworthy were the results obtained from the co-culture of Pestalotiopsis microspora and Trametes versicolor, which yielded degradation rates upwards of 50%, especially when wheat bran was employed as the carbon source. Furthermore, renewing culture media and inoculum significantly enhanced PSA biodegradation. These outcomes highlight the potential of fungal consortia in solid-state cultures to substantially improve the biodegradation of hybrid acrylic PSA films, providing valuable insights for the development of more sustainable adhesive bio-based products and contributing to the closure of the PSA lifecycle.