dc.contributor |
Háskóli Íslands |
dc.contributor |
University of Iceland |
dc.contributor.author |
Koroliov, Anton |
dc.contributor.author |
Chen, Genyu |
dc.contributor.author |
Goodfellow, Kenneth M. |
dc.contributor.author |
Vamivakas, A. Nick |
dc.contributor.author |
Staniszewski, Zygmunt |
dc.contributor.author |
Sobolewski, Peter |
dc.contributor.author |
Fray, Mirosława El |
dc.contributor.author |
Łaszcz, Adam |
dc.contributor.author |
Czerwinski, Andrzej |
dc.contributor.author |
Richter, Christiaan |
dc.contributor.author |
Sobolewski, Roman |
dc.date.accessioned |
2020-05-26T14:30:56Z |
dc.date.available |
2020-05-26T14:30:56Z |
dc.date.issued |
2019-01-23 |
dc.identifier.citation |
Koroliov, A.; Chen, G.; Goodfellow, K.M.; Vamivakas, A.N.; Staniszewski, Z.; Sobolewski, P.; Fray, M.E.; Łaszcz, A.; Czerwinski, A.; Richter, C.P.; Sobolewski, R. Terahertz Time-Domain Spectroscopy of Graphene Nanoflakes Embedded in Polymer Matrix. Applied Sciences 2019, 9, 391. |
dc.identifier.issn |
2076-3417 |
dc.identifier.uri |
https://hdl.handle.net/20.500.11815/1843 |
dc.description |
Publisher's version (útgefin grein) |
dc.description.abstract |
The terahertz time-domain spectroscopy (THz-TDS) technique has been used to obtain transmission THz-radiation spectra of polymer nanocomposites containing a controlled amount of exfoliated graphene. Graphene nanocomposites (1 wt%) that were used in this work were based on poly(ethylene terephthalate-ethylene dilinoleate) (PET-DLA) matrix and were prepared via a kilo-scale (suitable for research and development, and prototyping) in-situ polymerization. This was followed by compression molding into 0.3-mm-thick and 0.9-mm-thick foils. Transmission electron microscopy (TEM) and Raman studies were used to confirm that the graphene nanoflakes dispersed in a polymer matrix consisted of a few-layer graphene. The THz-radiation transients were generated and detected using a low-temperature-grown GaAs photoconductive emitter and detector, both excited by 100-fs-wide, 800-nm-wavelength optical pulses, generated at a 76-MHz repetition rate by a Ti:Sapphire laser. Time-domain signals transmitted through the nitrogen, neat polymer reference, and 1-wt% graphene-polymer nanocomposite samples were recorded and subsequently converted into the spectral domain by means of a fast Fourier transformation. The spectral range of our spectrometer was up to 4 THz, and measurements were taken at room temperature in a dry nitrogen environment. We collected a family of spectra and, based on Fresnel equations, performed a numerical analysis, that allowed us to extract the THz-frequency-range refractive index and absorption coefficient and their dependences on the sample composition and graphene content. Using the Clausius-Mossotti relation, we also managed to estimate the graphene effective dielectric constant to be equal to ~7 ± 2. Finally, we extracted from our experimental data complex conductivity spectra of graphene nanocomposites and successfully fitted them to the Drude-Smith model, demonstrating that our graphene nanoflakes were isolated in their polymer matrix and exhibited highly localized electron backscattering with a femtosecond relaxation time. Our results shed new light on how the incorporation of exfoliated graphene nanoflakes modifies polymer electrical properties in the THz-frequency range. Importantly, they demonstrate that the complex conductivity analysis is a very efficient, macroscopic and non-destructive (contrary to TEM) tool for the characterization of the dispersion of a graphene nanofiller within a copolyester matrix. |
dc.description.sponsorship |
This research was funded in part by the PumpPrimerII Program at the University of Rochester. A.N.V. acknowledges support from the Air Force Office of Scientific Research (FA9550-16-1-0020). M.E.F. acknowledges support from the Polish National Centre for Research and Development (PBS1/A5/2/2012). |
dc.format.extent |
391 |
dc.language.iso |
en |
dc.publisher |
MDPI AG |
dc.relation.ispartofseries |
Applied Sciences;9(3) |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
Drude-Smith model for complex conductivity |
dc.subject |
Graphene |
dc.subject |
Graphene nanoflakes |
dc.subject |
Graphene-polymer nanocomposites |
dc.subject |
Multiblock copolyesters |
dc.subject |
Terahertz time-domain spectroscopy |
dc.subject |
Nanótækni |
dc.subject |
Litrófsgreining |
dc.title |
Terahertz Time-Domain Spectroscopy of Graphene Nanoflakes Embedded in Polymer Matrix |
dc.type |
info:eu-repo/semantics/article |
dcterms.license |
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited |
dc.description.version |
Peer Reviewed |
dc.identifier.journal |
Applied Sciences |
dc.identifier.doi |
10.3390/app9030391 |
dc.relation.url |
http://www.mdpi.com/2076-3417/9/3/391/pdf |
dc.contributor.department |
Iðnaðarverkfræði-, vélaverkfræði- og tölvunarfræðideild (HÍ) |
dc.contributor.department |
Faculty of Industrial Eng., Mechanical Eng. and Computer Science (UI) |
dc.contributor.school |
Verkfræði- og náttúruvísindasvið (HÍ) |
dc.contributor.school |
School of Engineering and Natural Sciences (UI) |