In the past, climate change led the United Nations to define the Sustainable Development Goals Statement “blueprint to achieve a better and more sustainable future” and the European Commission to promote the “bioeconomy” concept and to launch the Green Deal Policy. Accordingly, the COP26 conference proposed a drastic reduction of fossil-based fuels and materials, in favor of biobased materials which should ensure intrinsic carbon neutrality. Contextually, many startups and established materials suppliers proposed new, trendy materials claiming sustainability advantages but, in many cases, without robust scientific backing. The need for transparency in terms of circularity led us to exploit a fast, reliable and easily deployable analytical method for assessing the biogenic carbon fraction in a variety of industrial materials. Our research team identified a radiocarbon analysis based on Saturated-absorption CAvity Ring-down (SCAR) spectroscopy as a quick and effective method for such a scope. Here we demonstrate its use for the determination of biogenic/fossil carbon proportions of polymeric and coated materials such as leather, coated textiles and trendy alternatives used in the fashion industry, with the scope of defining their intrinsic renewable content. The reliability of the SCAR method is validated through a comparison with the results obtained by the benchmark technique.

The elastic response of chromium-tanned leather was successfully improved by treatment with XSBR, a carboxylated styrene-butadiene copolymer. The carboxylic groups pending from a styrene-butadiene rubber (SBR) backbone were found to promote penetration of the aqueous polymer dispersion into the fibrous tanned leather and participated in pH-reversible physical crosslinking by H-bonding. The different penetrations of XSBR or SBR were investigated using a micro-FTIR cross-sectional analysis from the grain (outer) to the flesh (inner) side of 18 wt% elastomer-treated samples, based on the shaved leather weight. In particular, the profile of the diagnostic out-of-plane =C-H bending of butadiene and styrene units was consistent with a more effective penetration of XSBR. The leather with XSBR showed a comparatively lower elastic modulus of 10–15% and roughly a 10% increase in elongation at the break, indicating better flexibility and shape recovery. Also, the leather was characterized by a 15% higher burst strength. These results suggest the better swelling of the ionomeric XSBR in the initial stage of retanning performed at a pH higher than the isoelectric point of the leather when both the tanned leather and the XSBR ionomer had a negative surface charge. The high pH favored the penetration of XSBR due to a poor attractive interaction with the tanned fibrous leather network. Subsequent processing in an acid bath caused further physical crosslinking through hydrogen bonding between XSBR and the leather.