The structure of PA-Se-S-Cd composite materials probed with FTIR spectroscopy

Composite organic-inorganic functional materials are of significant importance in various applications of science and technology. In this work, PA-Se-S and PA-Se-S-Cd composite materials obtained by employing the sorption-diffusion method are discussed. A single precursor - K2SeS2O6 - was used as the source of both sulfur and selenium. In the aqueous solution, SeS2O62- and its decomposition products diffused into the polymer where they reacted with Cd2+ ions so that to form cadmium chalcogenide particles. Fourier-transform infrared (FTIR) spectroscopy was used to characterize the interactions between polyamide 6 and inorganic constituents, namely, K2SeS2O6, CdS and CdSe. The spectral behavior of amide I, II, A and B bands evidenced the competing formation of complex bonding structures based on the formation of covalent, electrostatic and hydrogen bonding between the PA 6 amide (NH-CO) groups and the inorganic constituents. The number and the type of the formed bonds depend on the polyamide 6 exposure time in the K2SeS2O6 precursor solution. Such a complex interaction induces obvious conformational changes of the polyamide 6 chains. A possible bonding mechanism has been proposed to explain the observed spectral phenomena.