Physicochemical and Mechanical Properties of Non-Isocyanate Polyhydroxyurethane (NIPHU) Films with Silver Nanoparticles (AgNPs)

Bio-based non-isocyanate polyhydroxyurethanes (NIPHUs) provide a versatile platform for functional polymeric materials while reducing dependence on conventional isocyanate-based polyurethane synthesis. In this work, soybean oil-derived NIPHU films were functionalized with silver nanoparticles (AgNPs) synthesized by biological routes using Solanum tuberosum and Acca sellowiana peel extracts, and by chemical reduction with sodium borohydride (NaBH4). This study was aimed at determining how formulation conditions affected AgNP formation, silver incorporation and the resulting physicochemical and mechanical properties. Plant extracts were characterized by phenolic compounds, reducing sugars and antioxidant activity, while AgNP formation was assessed by UV-vis spectroscopy, X-ray diffraction and ATR-FTIR. Functionalized films were characterized by wettability, mechanical performance, thermal stability, fluid absorption, total silver content and surface morphology. All routes enabled the formation of metallic AgNPs, while the films exhibited differences in silver incorporation and mechanical performance. The functionalized films generally exhibited increased wettability and mechanical resistance compared with the unfunctionalized NIPHU, whereas phosphate-buffered saline (PBS) uptake did not consistently increase and thermal stability of the NIPHU matrix was maintained. ST-4-30 showed the most balanced mechanical and physicochemical response. Overall, the AgNP synthesis route emerged as an effective formulation variable for tuning the properties of soybean oil-derived NIPHU films.