Influence of PDMS molecular weight on transparency and mechanical properties of soft polysiloxane-urea-elastomers for intraocular lens application
Autor: | Sibylle Thude, Solon Thanos, Günter Lorenz, Tobias Götz, Günter E. M. Tovar, Natascha Riehle, Andreas Kandelbauer |
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Rok vydání: | 2018 |
Předmět: |
chemistry.chemical_classification
Materials science Thermoplastic Polymers and Plastics Organic Chemistry General Physics and Astronomy Biomaterial Modulus 02 engineering and technology 021001 nanoscience & nanotechnology Elastomer Octamethylcyclotetrasiloxane 03 medical and health sciences Hysteresis 0302 clinical medicine chemistry 030221 ophthalmology & optometry Materials Chemistry Composite material Elongation 0210 nano-technology Refractive index |
Zdroj: | European Polymer Journal. 101:190-201 |
ISSN: | 0014-3057 |
Popis: | Soft thermoplastic polysiloxane-urea-elastomers (PSUs) were prepared for the application as a biomaterial to replace the human natural lens after cataract surgery. PSUs were synthesized from amino-terminated polydimethylsiloxanes (PDMS), 4,4′-Methylenebis(cyclohexylisocyanate) (H12MDI) and 1,3–Bis(3-aminopropyl)-1,1,3,3–tetramethyldisiloxane (APTMDS) by a two-step polyaddition route. Such a material has to be highly transparent and must exhibit a low Young’s Modulus and excellent dimensional stability. Polydimethylsiloxanes in the range of 3000–33,000 g·mol−1 were therefore prepared by ring-chain-equilibration of octamethylcyclotetrasiloxane (D4) and APTMDS in order to study the influence of the soft segment molecular weight on the mechanical properties and the transparency of the PSU-elastomers. 2,4,6,8-Tetramethyl-2,4,6,8-tetraphenylcyclotetrasiloxane (D4Me,Ph) was co-polymerized with D4 in order to adjust the refractive index of the polydimethyl-methyl-phenyl-siloxane-copolymers to a value equivalent to a young human natural lens. Very elastic PSUs with Elongation at Break values higher than 700% were prepared. PSU-elastomers, synthesized from PDMS of molecular weights up to 18,000 g·mol−1, showed transmittance values of over 90% within the visible spectrum range. The soft segment refractive index was increased through the incorporation of 14 mol % of methyl-phenyl-siloxane from 1.4011 to 1.4346 (37 °C). Young’s Moduli of PSU-elastomers were around 1 MPa and lower at PDMS molecular weights up to 15,000 g·mol−1. 10-cycle hysteresis measurements were applied to evaluate the mechanical stability of the PSUs at repeated stress. Hysteresis values at 100% strain decreased from 32 to 2% (10th cycle) with increasing PDMS molecular weight. Furthermore, hysteresis at 5% strain was only detected in PSU-elastomers with low PDMS molecular weights. Finally, preliminary results of in vitro cytotoxicity tests on a PSU-elastomer showed no toxic effects on HaCaT-cells. |
Databáze: | OpenAIRE |
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