The Role of Amide Groups in Vinyl Monomers Containing Siloxane Groups for Highly Oxygen Permeable Hydrogels
作者:Mitsuru Yokota、Hiroharu Ajiro、Mitsuru Akashi
DOI:10.1246/bcsj.20110366
日期:2012.5.15
In order to improve the hydrophilicity of silicone-containing monomers, N-2-(N′,N′-dimethylcarbamoyl)ethyl-N-[3-tris(trimethylsiloxy)silylpropyl]acrylamide (SiDAAA) and N-2-(N′,N′-dimethylcarbamoyl)ethyl-N-3-[methylbis(trimethylsiloxy)silyl]propyl}acrylamide (SiDAAA2) were designed. Although these two monomers had complicated side chain structures, these showed similar radical polymerizability (from 2.6 × 104 to 3.8 × 104 of Mn, and from 87 to 90% of conversion) as conventional silicone-containing monomer 3-tris(trimethylsiloxy)silylpropyl methacrylate (TRIS) due to the acrylamide backbone. Moreover, the additional amide group in those monomers contributed to improved miscibility during copolymerization with N-(hydroxyethyl)acrylamide (HEAA) and 2-hydroxyethyl methacrylate (HEMA), which was determined by light transmission observation at 88% transmittance using a SiDAAA/HEAA (50/50) hydrogel. In contrast, TRIS/HEAA was not miscible, and TRIS/HEMA (60/40) gave only 26% transmittance. The glass-transition temperatures of poly(SiDAAA) and poly(SiDAAA2) were 61 and 28 °C, which were much higher than that of poly(TRIS) at 0.8 °C. The oxygen permeability of the hydrogels varied with the copolymer composition, mainly due to the siloxanyl group contents. In particular, permeability coefficients of more than 100 Barrer (1 Barrer = 10−11 (cm3 O2) cm cm−2 s−1 mmHg−1) which is sufficient oxygen permeability for corneal safety in the case of contact lens applications, can be obtained at lower than 60% water content. The biocompatibility of these hydrogels is also discussed.
为了改善含有硅的单体的亲水性,设计了N-2-(N’,N’-二甲基氨基甲酰基)乙基-N-[3-三(三甲基硅氧基)硅丙基]丙烯酰胺(SiDAAA)和N-2-(N’,N’-二甲基氨基甲酰基)乙基-N-3-[甲基双(三甲基硅氧基)硅基]丙基}丙烯酰胺(SiDAAA2)。虽然这两种单体具有复杂的侧链结构,但由于其丙烯酰胺骨架,它们表现出与传统硅酮单体3-三(三甲基硅氧基)硅丙基甲基丙烯酸酯(TRIS)类似的自由基聚合性(Mn为2.6×104至3.8×104,转化率为87至90%)。此外,这些单体中额外的酰胺基团有助于与N-(羟乙基)丙烯酰胺(HEAA)和2-羟乙基甲基丙烯酸(HEMA)共聚时的相容性,通过SiDAAA/HEAA(50/50)水凝胶的光透射观察确定,透光率为88%。相比之下,TRIS/HEAA不相容,TRIS/HEMA(60/40)仅提供26%的透光率。聚(SiDAAA)和聚(SiDAAA2)的玻璃化转变温度分别为61°C和28°C,远高于聚(TRIS)的0.8°C。水凝胶的氧透过率随共聚物组成而变化,主要是由于硅氧烷基团含量。特别是,在水分含量低于60%的情况下,氧透过率系数可以超过100巴(1巴=10-11(cm3 O2)cm cm-2 s-1 mmHg-1),这对于隐形眼镜应用中的角膜安全性是足够的。这些水凝胶的生物相容性也在讨论中。