Lab for Thin Films - Nanobiomaterials - Nanosystems - Nanometrology


Development of transparent barrier coatings on polymeric substrates for packaging and Study of the adhesion and interface property

Greece-Germany Bilateral Project (2002-2004)
Coordination by LTFN
AUTh Sci. Responsible: Prof. S. Logothetidis

The development and production of transparent coatings of oxides (SiOx, AlOx) to coat the polymeric films with functional properties (high hardness, low friction coefficient, reflectivity, high oxygen and water vapor barrier properties) is a strongly demand in the field of flexible packaging. To meet this demand, the following two problems have to be solved: 1) The development of films aiming to surface modification of the polymeric films producing (oxide/polymeric substrate) systems, and 2) The improvement of the adhesion/bonding of different materials (oxides/polymers). Solving the above two problems is of high scientific and technological interest, and constitutes the objective of this project, since in addition to flexible packaging there is a wide range of applications in large scale optical systems (architecture building , cars), solar modules, microelectronics, flexible displays, etc. The complementary of the methods and characterization techniques applied by the Greek (EL) and German (DE) groups and their previous collaboration, expertise and available equipment ensure the successful completion of the project and strengthening of their collaboration in the field.

E-beam evaporation (EBE) is the main technique used for the deposition of transparent films onto polymers. The technical demands for transparent, functional coatings onto polymeric substrates are :

  • Good adhesion of the deposited coatings to the substrates
  • Well defined optical and barrier properties
  • Good wear resistance.

The main expected achievements of the project are:

  • The determination of the modification of the polymeric films technique to improve the adhesion of the deposited coatings to the substrate
  • The good optical response and wear resistance of the producing (oxide/polymeric substrate) systems
  • The high barrier properties of the coated polymeric films
  • The in-situ and real-time monitoring of the growth process

To achieve the above tasks the following techniques will be used: (i) low energy atomic beams and oxygen plasma techniques for the modification of the polymeric substrates in vacuum, (ii) growth of transparent films by EBE and computational methods/modelling of the films' growth and (iii) atomic level characterization techniques such as Spectroscopic Ellipsometry (IR-Vis-UV) for in-situ and real-time monitoring of the deposition process, X-rays Photoelectron Spectroscopy (XPS) to determine molecular composition and binding states of the elements on the surface, Atomic Force Microscopy (AFM) for surface roughness and topography study, Nanoindentation and Nanoscratching for mechanical properties measurements, as well as Peel-test for the measurement of the adhesion strength of the deposited transparent coatings and oxygen permeability measurements.

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