Abstract 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.

中文翻译：

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PDMS 分子量对人工晶状体用软聚硅氧烷-脲-弹性体透明度和机械性能的影响

摘要 制备了柔软的热塑性聚硅氧烷-脲-弹性体（PSUs），作为一种生物材料，用于在白内障手术后替代人类天然晶状体。PSU 由端氨基聚二甲基硅氧烷 (PDMS)、4,4'-亚甲基双(环己基异氰酸酯) (H12MDI) 和 1,3-双(3-氨基丙基)-1,1,3,3-四甲基二硅氧烷 (APTMDS) 合成两步加聚路线。这种材料必须高度透明，并且必须表现出低杨氏模量和出色的尺寸稳定性。因此，通过八甲基环四硅氧烷 (D4) 和 APTMDS 的环链平衡制备了 3000–33,000 g·mol-1 范围内的聚二甲基硅氧烷，以研究软链段分子量对机械性能和透明性的影响。 PSU-弹性体。2,4,6,8-四甲基-2,4,6, 8-四苯基环四硅氧烷 (D4Me,Ph) 与 D4 共聚，以将聚二甲基-甲基-苯基-硅氧烷-共聚物的折射率调整到与年轻人类天然晶状体相当的值。制备了断裂伸长率值高于 700% 的非常有弹性的 PSU。由分子量高达 18,000 g·mol-1 的 PDMS 合成的 PSU 弹性体在可见光谱范围内显示出超过 90% 的透射率值。通过掺入 14 mol% 的甲基苯基硅氧烷，软链段的折射率从 1.4011 增加到 1.4346（37 °C）。PSU 弹性体的杨氏模量约为 1 MPa，并且在 PDMS 分子量高达 15,000 g·mol-1 时更低。应用 10 周期滞后测量来评估 PSU 在重复应力下的机械稳定性。随着 PDMS 分子量的增加，100% 应变下的滞后值从 32% 降低到 2%（第 10 次循环）。此外，仅在具有低 PDMS 分子量的 PSU 弹性体中检测到 5% 应变时的滞后。最后，对 PSU 弹性体的体外细胞毒性试验的初步结果显示对 HaCaT 细胞没有毒性作用。