No JavaScript support!

To take full advantage of this digital library, please verify if your browser supports JavaScript.

polski

English

dLibra Digital Library

readers on-line: 31

Edition

Export metadata

Favourite positions

Add to Favourites

Add to Favourites

Please login or register to use additional features!

Save this address

Add to bookmarks

Edition description

Analiza nanostruktury polimerowych soczewek kontaktowych z wykorzystaniem spektroskopii czasów życia pozytonów PALS

Show publication content!

Analiza nanostruktury polimerowych soczewek kontaktowych z wykorzystaniem spektroskopii czasów życia pozytonów PALS

Kocela, Agnieszka

Filipecki, Jacek. Promotor ; Korzekwa, Witold. Promotor pomocniczy

soczewki kontaktowe ; pozyton ; spektroskopia

The major objective of the project is an attempt at explaining the effect of structural parameters on oxygen as the most important criterion for safe use of lenses. In order to achieve the objective, there was a complete study of methodology of the positron annihilation lifetime spectroscopy (PALS) technique carried out. The technique is designed to examine functional modification of the natural structure of nanogaps in modern polymer materials used in manufacturing hydrogel and silicone-hydrogel contact lenses. Additionally, there were also UV-vis-NIR, MIR and Ramana spectroscopic studies carried out in the project. The most important results obtained in the project can be summed up as follows:1. Analysis of the τ1 component of the spectrum characterising the p – Ps trapping annihilation, positron annihilation with free electrons or loosely attached in cation vacancies did not show any significant division between hydrogel and silicone-hydrogel lenses. 2. On the basis of interpretation of the τ1 component characterising the annihilation connected with positron trapping in the existing free molecular volumes, a clear division was obtained between hydrogel and silicone-hydrogel lenses, which proves existence of higher molecular volumes in the silicone-hydrogel lenses. 3. An analysis of two-state positron trapping showed that the silicone-hydrogel lenses are distinguished by larger sizes of defects, in which annihilation occurs in relation to the silicone-hydrogel lenses and by higher rate of positron capturing by the defects. 4. Mathematical analysis of the third positron lifetime component, reflecting the “pick – off” trapping of o – Ps by free volumes, provided clear information about geometrical parameters of free volumes. The hydrogel lenses are characterised by significantly smaller dimensions of free volumes in relation to the silicone – hydrogel lenses. A value of the fv /C, i.e. the quotient of polymer free volume to macroscopic free volume is also higher for the silicone – hydrogel lenses. 5. One of the objectives of this project was examination of the results of physical studies in relation to medical aspects of biopolymers. The consequence of existence of larger free volumes and occurrence of larger numbers of free volumes in the silicone – hydrogel lenses is a higher oxygen-transmission coefficient, very important for correct functioning of the cornea in a human eye. 6. The UV-vis-NIR studies suggest one major conclusion that all the examined hydrogel and silicone – hydrogel contact lenses properly stop the harmful 245 nm ultraviolet radiation. 7. In the spectrum of each lens, MIR and Ramana spectroscopic studies showed a clear, characteristic peak for bending and stretching the O – H vibrations taking place in water particles.

Place of publishing:

Częstochowa

Akademia im. Jana Długosza w Częstochowie ; Wydział Matematyczno-Przyrodniczy

2015

rozprawa doktorska

application/pdf

oai:dlibra.bg.ajd.czest.pl:3047

80000199

pol

Praca opublikowana na podstawie licencji udzielonej przez Autora

Location of original object:

Biblioteka Główna Akademii im. Jana Długosza w Częstochowie