Silver nanoparticles (AgNPs) synthesized on the surface of chitosan (CS) films using ultraviolet (UV) and natural light irradiation reduction methods were studied. Field-emission scanning electron ...microscopy revealed that the diameter of some AgNPs synthesized by the UV irradiation reduction method lay in the range of 5–15 nm. These AgNPs were isolated and dispersed on the surface of CS film. Meanwhile, some AgNPs aggregated to form larger cubic and irregular AgNPs with average size of 50–200 nm. Compared with those synthesized via the UV irradiation reduction method, AgNPs synthesized by the natural light irradiation reduction method were found to be much more individually isolated and uniformly dispersed on the CS film surface. The AgNPs synthesized using the natural light irradiation reduction method had spherical shape with average size of 10–30 nm. Thus, the size and morphology of AgNPs on the CS films (CS-AgNPs films) can be controlled by choosing an appropriate irradiation reduction method. The results of antibacterial testing illustrated that the CS-AgNPs films synthesized by both the ultraviolet and natural light irradiation reduction methods exhibited strong antibacterial activity against
Escherichia coli
.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Waterborne polyurethane (WPU) was synthesized and followed by adding colloidal silica to prepare WPU–silica hybrids. The silica content in the hybrid thin films was varied from 0 to 50 wt%. The ...experimental results revealed that the viscosity of these hybrid solutions increased with increasing silica content and resulted in the aggregation of silica particle in the hybrid films. The latter result was evidenced by SEM examination. The effect of interaction between silica particle and urethane polymer chains is more significant with increasing silica content. The prepared hybrid films show much better thermal stability and mechanical properties than pure WPU. The optical transparence did not linearly decrease with increasing the silica fraction in the hybrid thin film. At below 20% silica content, the film transparence decreased with increasing silica content; the converse is true at above 20% silica content. These results showed that the prepared hybrid films demonstrated tunable transparence with the silica fraction in the films.
Transmittance variation of the hybrid films (ca. 0.5 mm thickness) with different silica content over a wavelength range of 200–1100 nm. As shown in the inset, the transmittance at 633 nm decreases from 92% of pure WPU to 20% of the hybrid with 20% silica content, and then gradually increases from 20 to 87% of the hybrid with 50% silica content.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Polyaniline (PANI) co-doped with nitric acid (HNO
3
) and dodecyl benzene sulfonic acid (DBSA) was directly prepared by the chemical oxidative polymerization of aniline in an aqueous solution. When ...the molar ratio of HNO
3
/DBSA was 0.3:7, the resulted co-doped PANI (PANI
H0.3D7
) reached a maximum electrical conductivity of 7.98 S/cm. When the molar ratio of HNO
3
/DBSA was 0.4:6, the resulted co-doped PANI (PANI
H0.4D6
) exhibited a maximum yield of 70.09%. Thermogravimetric analysis (TGA) results illustrated that there were four weight loss stages in the co-doped PANI. These weight losses were resulted from the evaporation of moisture, HNO
3
, DBSA, and PANI respectively. TGA results also indicated that approximately 10.04 and 3.32 repeating units of PANI were doped with one HNO
3
molecule and one DBSA molecule in the co-doped PANI
H0.3D7
, respectively. Fourier transform infrared (FTIR) results showed that the absorption peaks of the −C═C− and −C
aromatic
−N− stretching vibrations in the emeraldine salt (ES) PANI were all shifted to the lower wavenumbers than those in the emeraldine base (EB) PANI. It was worth noting that the morphology of PANI was strongly affected by polymerization conditions.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The effects of dioctyl phthalate (DOP) loading on morphology and thermal and mechanical properties of the poly(vinyl chloride)/organically modified montmorillonite/DOP (PVC/O-MMT/DOP) nanocomposites ...are studied in this paper. Results of transmission electron microscope (TEM) indicate that O-MMT is partially intercalated and exfoliated in all PVC/O-MMT/DOP nanocomposites. It shows that the addition of DOP has no obvious influence on the dispersion of O-MMT in the PVC/O-MMT/DOP nanocomposites. Young’s modulus and tensile strength of the PVC/O-MMT/DOP nanocomposites are significantly decreased as the amount of DOP is increased. The thermal degradation onset temperature and glass transition temperature (
T
g
) of the PVC/O-MMT/DOP nanocomposites are decreased as the amount of DOP is increased. On the other hand, the elongation at break of the PVC/O-MMT/DOP nanocomposites is increased as the amount of DOP is increased. Also, the first thermal degradation weight loss (Δ
Y
) of the PVC/O-MMT/DOP nanocomposites is increased as the amount of DOP is increased. While increasing DOP loading, the PVC/O-MMT/DOP nanocomposites change from a rigid product to a semirigid product and finally into a flexible product.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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