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The purpose of this thesis was the design, synthesis and characterization of novel flexible polymers with high refractive index (HRI) for application as intraocular lens (IOL) material. To be suitable as ophthalmic implant, the material needs to achieve several parameters of physical, medical and chemical nature. The components of this multi-parameter-system tend to interfere with each other. Therefore, the polymer design was disassembled into three segments (HRI group, spacer unit, polymerizable group) and analyzed separately regarding the relationship between chemical structure and physical properties.
Overall ten different HRI homopolymers based on a methacrylate backbone and siloxane backbone have been synthesized by variation of the polymerizable group. Five of them were described for the first time. The obtained refractive indices ranged between nD = 1.567 – 1.645 with ABBE numbers νA = 20.3 – 33.7. Substituting the methacrylate unit with a siloxane unit heavily increased the flexibility of the materials, resulting in a glass transition temperature decrease from Tg,PMA = 66 – 110 °C to Tg,PSX = -15 – 49 °C. By comparison of the properties, a straight¬forward calculation system for estimation of the core parameters nD, vA and Tg preliminary to the synthesis was developed. Furthermore, important characteristics like transmission in the ultraviolet and visible range and lightfastness of the materials were determined. The variation of the aliphatic spacer group was performed in a synthesis of six monomers with direct linkage and 14 monomers with spacer groups with an atomic structure of –(CH2)s– in a range of s = 2 – 12. Besides the respective homopolymers of polyacrylate and polymeth¬acrylate type, five copolymers were also synthesized to uncover differences and similarities in the physical trends. All core parameters were brought into range of the designated target (nD = 1.551 – 1.633; νA = 24.4 – 33.4; Tg = -26 – 149 °C) using spacer alter¬nation. Computational coherences between the parameters and physical differences between polyacrylates and polymethacrylates were determined. This enables the possibility of a tuning of the polymer properties, which was successfully applied to other HRI systems. The glistening affinity also showed a structural dependency, providing the opportunity for improvement.
The variation of the HRI group started with the synthesis of 16 different polyacrylates and polymethacrylates containing monoaryl and biaryl functions of different substitution. Six novel, highly transparent polymers with a triaryl ether function and aliphatic spacers (s = 2) were developed based on the gained experience. Since the used structures were constitutional isomers, the influence of the layout on the physical properties could be investigated. The refractive indices ranged from nD = 1.617 – 1.626 (νA = 26.1 – 28.0) with glass transition temperatures between Tg = 47 – 62 °C. Concluding, a coherent scoring and calculation system for copolymers was developed. Based on this system, flexible HRI materials with good optical quality and low glass transition temperatures were synthesized. The machinability of these materials has been proven by preparation of intraocular lenses (IOLs) and phakic intraocular lenses (pIOLs). The unfolding process and biocompatibility examination also showed promising results in concluding tests in the animal model and qualifies the material for application in a novel IOL lens.