Investigation of the Degree of Disorder of the Structure of Polymer Soft Contact Lenses Using Positron Annihilation Lifetime Spectroscopy PALS.

Background: Hydrogel and silicone-hydrogel polymeric materials are widely used in ophthalmology for the manufacture of contact lenses. An important aspect is the investigation of the structure of these materials.

Objectives: This study has been conducted in order to compare the degree of disorder and presence of free volumes in the internal structure of the polymeric soft contact lenses Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel).

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

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.

Ageing phenomenon in acrylic polymer dental materials detected by means of positron annihilation lifetime spectroscopy.

Background: Polymer materials based on acrylic monomers are commonly used in dentistry. It is important to research the structure of dental filling materials towards the material ageing.

Objectives: The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer materials.

Voids in mixed-cation silicate glasses: Studies by positron annihilation lifetime and Fourier transform infrared spectroscopies.

PALS in comparison with FTIR studies have been applied to investigate the structure of different oxide glasses. Three components of the positron lifetime τ (τ1 para- and τ3 ortho-positronium and τ2 intermediate lifetime component) and their intensities were obtained. The results of the calculation of mean values of positron lifetimes for the investigated glasses showed the existence of a long-living component on the positron annihilation lifetime spectra.

Structural studies of polymer hydrogel and silicone hydrogel contact lenses by means of positron lifetime spectroscopy methods.

Unlabelled: PURPOSE OF JOB: Currently, there isa need to increase comfort and visual acuity man. Simultaneously improving biocompatibility and minimizing the impact of the material on the physiology of the cornea is the primary driving force behind the evolution of materials used in the manufacture of contact lenses. Despite progressive development of modern materials science, there is still the problem of reducing the level of oxygen available to the cornea resulting in pathological changes in the cornea.