The effects of silver nitrate on the structure and properties of polyurethanes containing pyridyl units

In this study, 2,6-pyridinedimethanol was used as a chain extender to synthesize a new polyurethane, PDM-PU. Further, various amounts of silver nitrate were incorporated to produce PDM-PU/AgNO3 complexes. FT-IR and UV–Vis analyses confirm the formation of complex in the PDM-PU/AgNO3. DSC and DMA results show that the glass transition temperature (Tg), dynamic Tg and storage modulus at 25 °C of the PDM-PU/AgNO3 complexes increase with increasing AgNO3 content. This is due to the formation of complex structure that can restrict the segmental motion of polymer chains. The TGA and stress–strain test results show that the thermal decomposition temperature, tensile strength and elongation at break increase with the AgNO3 content initially. Then, they decrease inversely. This indicates that the formation of complex structure raises these properties when the AgNO3 content is below certain value. But as more coordinate bonds were formed, the specimens become brittle. In addition, the crosslink effect caused by coordinate bonds inhibits the dissolution of polymer chains and thereby reduces the swelling degree of the complexes in solvent. Furthermore, AgNO3 imparts antibacterial activity against S. aureus and K. pneumoniae to the complexes