Silver/polyaniline nanocomposites (Ag NPs/PANI) containing PANI nanofiber and Ag nanoparticles were synthesized by one-step approach without using any extra reducing agent or surfactant and applied to new antimicrobial agents. Morphologies and crystallinity of the nanocomposites were characterized with SEM and XRD. The results showed that the average diameter of the PANI nanofibers is around 50-150 nm, and the average particle size of Ag NPs is around 100 nm. The crystallinity of PANI gets better with increasing silver nitride concentration. UV-vis absorption spectroscopy analysis indicated that the Ag NPs have some effect on the microstructure of PANI. The antimicrobial properties of Ag NPs/PANI against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus and fungous Yeast were evaluated using viable cell counts. The test results demonstrated that Ag NPs/PANI have enhanced antimicrobial efficacy compared to that of pure Ag NPs or pure PANI under the same test condition. The mechanism of the synergistic antimicrobial effect of Ag NPs with PANI was also proposed. In addition, thermal gravity analysis indicated that pure PANI and Ag NPs/PANI exhibit better thermal stability.
BACKGROUND: Polyaniline (PANI) has attracted much attention in many fields due to its chemical and physical properties, and different nanostructures of PANI changing from one-dimensional to three-dimensional have been obtained. By changing the concentration of cetyltrimethylammonium bromide (CTAB), the morphology of hydrochloric acid-doped polyaniline could be changed from one-dimensional nanoneedles or nanowires with a network structure (50-100 nm in diameter) to three-dimensional hollow microspheres (ca 400 nm in outer diameter) via combining interfacial polymerization and self-assembly process.
RESULTS: These different nanostructures of PANI were proved using scanning electron and transmission electron microscopies. A plausible mechanism of the formation of the changeable nanostructures of PANI may be different from that of interfacial polymerization without surfactant or a traditional homogenous reaction system using CTAB as surfactant.CONCLUSION: The results obtained from Fourier transform infrared spectrometry, X-ray diffraction and the four-probe method showed that the molecular structure of PANI does not change with increasing CTAB concentration, but crystallinity and conductivity of PANI increase with surfactant concentration.
To enhance SO 2 utilization, improve fertilizer use efficiency, and minimize the negative environmental impact, the novel slow release sulfurcontaining urea fertilizers with good biodegradation performance were developed by coating with the sustainable poly(eugenol sulfone) derived from renewable eugenol and SO 2 . The poly(eugenol sulfone) was synthesized by a simple free radical polymerization under mild conditions, and structural features of the synthesized copolymers were studied by various characterization techniques. Characterization results revealed that the copolymers exhibited the strict alternating copolymerization structures containing OSO. A set of systematically designed experiments were carried out to determine the influences of the amount of initiator, reaction time, and reaction temperature on the molecular structure, release, and biodegradation behavior of the coated fertilizers. The obtained results proved that the coated fertilizers showed excellent release and biodegradation features. Moreover, the release and biodegradation rate of the coated fertilizers can be adjusted by changing the molecular weight of poly(eugenol sulfone). In addition, the kinetic study on the slow release characteristics of poly(eugenol sulfone)-coated fertilizers showed that the best fitting effect was obtained by the Ritger−Peppas equation. This work offers a simple and useful strategy for designing sulfur-containing urea fertilizers with excellent slow release and biodegradation performance and provides a new route for sulfur recycling. In the future, the fertilizer will be deeply tested to evaluate their impact on plant growth, chemical, and biological soil properties.
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