Studying functional properties of hydrogel and silicone–hydrogel contact lenses with PALS, MIR and Raman spectroscopy

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 131; pp. 686 - 690
• Main Authors: Filipecki, J., Sitarz, M., Kocela, A., Kotynia, K., Jelen, P., Filipecka, K., Gaweda, M.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15-10-2014
• Subjects: Contact Lenses; Electrons; Free volume; Hydrogel, Polyethylene Glycol Dimethacrylate - chemistry; Materials Testing; MIR; Polymers; Polymers - chemistry; Porosity; Positron annihilation; Raman spectroscopy; Silicones - chemistry; Spectrophotometry, Infrared; Spectrum Analysis, Raman; Free volume; Positron annihilation; Polymers; Raman spectroscopy; Contact lenses; MIR
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2014.04.144

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•The evolution of production of contact lenses affect on the physiology of the eye.•The structure of contact lenses were examined by means of PALS, MIR & Raman methods.•Dependence between the free volumes in polymer contact lenses has been demonstrated.
Determination of free volume holes of the hydrogel and silicone–hydrogel polymer contact lenses were investigated. Two types of polymer contact lenses were used as materials: the first is a hydrogel contact lenses Proclear family (Omafilcon A), while the second is a silicone–hydrogel contact lens of the family Biofinity (Comfilcon A). Positron annihilation lifetime spectroscopy PALS was used to characterize geometrical sizes and fraction of the free volume holes in the investigated samples. There is a clear difference in the free volume sizes and their fractions between silicone–hydrogel and polymer hydrogel contact lenses which in turn are connected with oxygen permeability in these lenses. Apart from that, spectroscopic (middle infrared) MIR and Raman examinations were carried out in order to demonstrate the differences of the water content in the test contact lenses.