Search

Copyright of Lithuanian Journal of Physics is the property of Lithuanian Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present study, pure poly(dimethylsiloxane) (PDMS) polymer and PDMS-detonation nanodiamond (PDMS-DND) composite with 1 wt. % of DND were irradiated under vacuum at room temperature with a 2 MeV proton beam with fluences in the 1013–1015 cm-2 range. Modification of the structures and properties of the pure polymer and the nanocomposite material were monitored as a function of proton fluence. Specifically, the vibrational dynamics of pure PDMS and PDMS-DND nanocomposites, both unirradiated and irradiated samples, were investigated using Raman and Fourier transform infrared spectroscopy (FTIR). The Raman and FTIR spectra of the PDMS and PDMS-DND composites exhibit an overall reduction in intensity of all vibrational bands of the irradiated samples. The changes in relative intensities of the characteristic vibrational bands as a function of irradiation fluence indicate that cleavage of the backbone (Si–O–Si) PDMS chains was most pronounced. Importantly, structural degradation of PDMS-DND composites takes place at an order of magnitude higher fluence than for pure PDMS, indicating the potential of using DND-based polymer composites for application in high radiation environments. The appearance of strong photoluminescence following irradiation was more pronounced for PDMS-DND composites as compared to pure PDMS. [ABSTRACT FROM AUTHOR]

Pure poly(dimethylsiloxane) (PDMS) films, PDMS-nanodiamond (ND) and pure nanodiamond powder were irradiated with 2 MeV protons under a variety of fluence and current conditions. Upon proton irradiation, these samples acquire a fluence-dependent photoluminescence (PL). The emission and excitation spectra, photostability and emission lifetime of the induced photoluminescence of PDMS and PDMS-ND samples are reported. Pure PDMS exhibits a noticeable stable blue PL, while the PDMS-ND composites exhibit a pronounced stable green PL under 425 nm excitation. The PL of PDMS-ND composites is much more prominent than that of pure PDMS or pure ND powder even when irradiated at higher doses. The origin of the significantly enhanced PL intensity for the proton-irradiated PDMS-ND composite is explained by the combination of enhanced intrinsic PL within ND particles due to ion-implantation-generated defects and by PL originating from structural transformations produced by protons at the nanodiamond/matrix interface.