Physico-Chemical Properties of Polymer Nanocomposites
Islam Ali Elsayed Ali;
Abstract
In this work, series of Ag/PS/PVP nanocomposites via facile and novel synthetic steps were prepared. Our synthetic route is simpler; it does not need expensive oxidizing agents, surfactants, templates and complicated apparatus.
The present work contains five chapters in addition to the list of figures, tables, abbreviations and references. The first two chapters are concerned with the introduction and literature reviews of previous studies.
Chapter 3 describes the preparation methodology, experimental setup and techniques used in the Ag/PS/PVP nanocomposites microsphere processing and analysis. Ag nanoparticles with different particle sizes were prepared via γ- irradiation method. Several techniques were used to detect the structural changes of the nanocomposites due to interaction between Ag ions and PS/PVP. These are: ultraviolet-visible spectrophotometer, transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectrophotometer and Thermogravimetric analysis (TGA)
Chapter 4 includes the obtained results and their discussions:
Ultraviolet/Visible spectroscopy (UV/VIS) investigated that the as-prepared Ag nanocomposites have improved optical properties. Such incremented optical properties were attributed to the nanoscale dispersion (nm). The improvement in the optical properties is considered to be dependent on, Ag concentration and irradiation dose. The surface plasmon peaks appearing in the visible region (400-435 nm) for Ag/PS/PVP nanocomposite microspheres are characteristic of the metal nanoparticles.
The obtained data regarding the change of the absorption intensity and wavelength at maximum absorption and the size of Ag nanoparticles pointed the followingremark: The particle size of Ag nanoparticles in the asprepared Ag/PS/PVP nanocomposite microspheres decreases with increasing irradiation dose and increase with increasing either Ag+ ion concentration or PVP content. The calculated band gap energies Ag/PS/PVP nanocomposites are higher than that of bulk of Ag indicating the strong quantum confinement. The increases in the band gap energy have been attributed to the crystalline size dependent properties.
Transmission electron microscope images illustrated that the nanostructured Ag/PS/PVP microspheres were found to be dispersed spherical nanoparticales with good structural homogeneity and polydispersity at either lower concentration of AgNO3 and/or irradiation dose. Spherical structure of Ag accompanied with small agglomeration appeared in the as-prepared nanocomposites at either higher AgNO3 concentration or irradiation dose.
Transmission electron microscope images illustrated that the average diameter of the Ag nanoparticles is indicatedas the peak position of the Gaussian curves of the histogram to be from 10-40 nm. The nanostructured Ag/PS/PVP microspheres were found to be dispersed spherical nanoparticles with good structural homogeneity and polydispersity.
The XRD pattern of irradiated Ag/PS/PVP nanocomposite samples show four new diffraction peaks which reveal that the Ag nanoparticles are formed in thePS/PVP matrix and their crystal structure is face center cubic (fcc) structure. Also, it can be seen that, with increasing irradiation dose, the particle size decreases, whereas the particle size increase gradually with increasing AgNO3 concentration. The calculated particle sizes of Ag nanoparticles using UV/VIS, TEM and XRD data are in good agreement with each other, consistent and dependent on the theory of examination.
FTIR spectra illustrate that the formation of Ag/PS/PVP nanocomposites leads to disappearance and/or weakening of some characteristic peaks followed by the change in peak position, peak shape and peak intensity due to incorporation of various content of Ag nanoparticles and irradiation doses. Decrease in the transmittance of somebands reveals that there is an interaction between Ag and PS/PVP.
Thermal gravimetric analysis (TGA) showed that, pure PS/PVP sample proceed in three main weight loss stages between 45-190 Co, 250-350 Co and 350-450 C°. The appearance of the fourth stage withincorporation of Ag nanoparticles; confirm the coordination between AgNPs and NH groups. Finally, from the thermal parameters of Ag/PS/PVP degradation reaction, thermal stability of Ag/PS/PVP nanocomposites is higher than in pure PS/PVP.
The present work contains five chapters in addition to the list of figures, tables, abbreviations and references. The first two chapters are concerned with the introduction and literature reviews of previous studies.
Chapter 3 describes the preparation methodology, experimental setup and techniques used in the Ag/PS/PVP nanocomposites microsphere processing and analysis. Ag nanoparticles with different particle sizes were prepared via γ- irradiation method. Several techniques were used to detect the structural changes of the nanocomposites due to interaction between Ag ions and PS/PVP. These are: ultraviolet-visible spectrophotometer, transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectrophotometer and Thermogravimetric analysis (TGA)
Chapter 4 includes the obtained results and their discussions:
Ultraviolet/Visible spectroscopy (UV/VIS) investigated that the as-prepared Ag nanocomposites have improved optical properties. Such incremented optical properties were attributed to the nanoscale dispersion (nm). The improvement in the optical properties is considered to be dependent on, Ag concentration and irradiation dose. The surface plasmon peaks appearing in the visible region (400-435 nm) for Ag/PS/PVP nanocomposite microspheres are characteristic of the metal nanoparticles.
The obtained data regarding the change of the absorption intensity and wavelength at maximum absorption and the size of Ag nanoparticles pointed the followingremark: The particle size of Ag nanoparticles in the asprepared Ag/PS/PVP nanocomposite microspheres decreases with increasing irradiation dose and increase with increasing either Ag+ ion concentration or PVP content. The calculated band gap energies Ag/PS/PVP nanocomposites are higher than that of bulk of Ag indicating the strong quantum confinement. The increases in the band gap energy have been attributed to the crystalline size dependent properties.
Transmission electron microscope images illustrated that the nanostructured Ag/PS/PVP microspheres were found to be dispersed spherical nanoparticales with good structural homogeneity and polydispersity at either lower concentration of AgNO3 and/or irradiation dose. Spherical structure of Ag accompanied with small agglomeration appeared in the as-prepared nanocomposites at either higher AgNO3 concentration or irradiation dose.
Transmission electron microscope images illustrated that the average diameter of the Ag nanoparticles is indicatedas the peak position of the Gaussian curves of the histogram to be from 10-40 nm. The nanostructured Ag/PS/PVP microspheres were found to be dispersed spherical nanoparticles with good structural homogeneity and polydispersity.
The XRD pattern of irradiated Ag/PS/PVP nanocomposite samples show four new diffraction peaks which reveal that the Ag nanoparticles are formed in thePS/PVP matrix and their crystal structure is face center cubic (fcc) structure. Also, it can be seen that, with increasing irradiation dose, the particle size decreases, whereas the particle size increase gradually with increasing AgNO3 concentration. The calculated particle sizes of Ag nanoparticles using UV/VIS, TEM and XRD data are in good agreement with each other, consistent and dependent on the theory of examination.
FTIR spectra illustrate that the formation of Ag/PS/PVP nanocomposites leads to disappearance and/or weakening of some characteristic peaks followed by the change in peak position, peak shape and peak intensity due to incorporation of various content of Ag nanoparticles and irradiation doses. Decrease in the transmittance of somebands reveals that there is an interaction between Ag and PS/PVP.
Thermal gravimetric analysis (TGA) showed that, pure PS/PVP sample proceed in three main weight loss stages between 45-190 Co, 250-350 Co and 350-450 C°. The appearance of the fourth stage withincorporation of Ag nanoparticles; confirm the coordination between AgNPs and NH groups. Finally, from the thermal parameters of Ag/PS/PVP degradation reaction, thermal stability of Ag/PS/PVP nanocomposites is higher than in pure PS/PVP.
Other data
| Title | Physico-Chemical Properties of Polymer Nanocomposites | Other Titles | "الخواص الفيزيائية والكيميائية لمركبات البوليمر النانومترية " | Authors | Islam Ali Elsayed Ali | Issue Date | 2015 |
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