Christopoulos, Stavros

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Christopoulos, Stavros
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s.christopoulos@sorbonne.ae
ORCID
0000-0002-4877-6225
Scopus Author ID
16063314100
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  • Publication
    Comparative Study of Polyethylene Films Embedded with Oxide Nanoparticles of Granulated and Free-Standing Nature
    (2022)
    Christopoulos, Stavros 
    ;
    Slimani, Ahmed 
    ;
    Li, Liang 
    ;
    Le Guyon, Valerie
    ;
    Bsaibess, Eliane 
    ;
    Joumana, El-Rifai 
    ;
    Angastiniotis, Nicos
    ;
    Koutsokeras, Loukas
    ;
    Duponchel, Benoît
    Nanocomposite polymer films are a very diverse research field due to their many applications. The search for low-cost, versatile methods, producing regulated properties of the final products, has thus become extremely relevant. We have previously reported a bulk-scale process, dispersing granulated metal oxide nanoparticles, of both unary and multi-component nature, in a low-density polyethylene (LDPE) polymer matrix, establishing a reference in the produced films’ optical properties, due to the high degree of homogeneity and preservation of the primary particle size allowed by this method. In this work, unmodified, free-standing particles, namely zinc oxide (ZnO), titanium dioxide (TiO2), aluminum oxide (Al2O3), and silicon dioxide (SiO2) are blended directly with LDPE, and the optical properties of the fabricated films are compared to those of films made using the granulation process. The direct blending process evidently allows for control of the secondary particle size and ensures a homogeneous dispersion of the particles, albeit to a lesser extent than the granulation process. Despite the secondary particle size being comparatively larger than its granulated counterpart, the process still provides a regulated degree of deagglomeration of the free-standing oxide particles, so it can be used as a low-cost alternative. The regulation of the secondary particle size tunes the transmission and reflection spectra, in both unary and mixed oxide compositions. Finally, the direct blending process exhibits a clear ability to tune the energy band gap in mixed oxides.
      85  174
  • Publication
    Controlling the optical properties of nanostructured oxide-based polymer films
    (2021)
    Christopoulos, Stavros 
    ;
    Angastiniotis, N. C.
    ;
    Petallidou, K. C.
    ;
    Efstathiou, A. M.
    ;
    Othonos, A.
    ;
    Koutsokeras, L.
    A bulk scale process is implemented for the production of nanostructured film composites comprising unary or multi-component metal oxide nanoparticles dispersed in a suitable polymer matrix. The as-received nanoparticles, namely Al[Formula: see text]O[Formula: see text], SiO[Formula: see text] and TiO[Formula: see text] and binary combinations, are treated following specific chemical and mechanical processes in order to be suspended at the optimal size and composition. Subsequently, a polymer extrusion technique is employed for the fabrication of each film, while the molten polymer is mixed with the treated metal oxide nanoparticles. Transmission and reflection measurements are performed in order to map the optical properties of the fabricated, nanostructured films in the UV, VIS and IR. The results substantiate the capability of the overall methodology to regulate the optical properties of the films depending on the type of nanoparticle formation which can be adjusted both in size and composition.
    Scopus© Citations 12  130  84