Zhao Zheng-Bai, An Shuang-Shuang, Xie Hai-Jiao, Han Xue-Lian, Wang Fu-He, Jiang Yong
†School of Chemistry and Chemical Engineering, Southeast University, Jiangning, Nanjing, Jiangsu 211189, P. R. China.
J Phys Chem B. 2015 Jul 30;119(30):9780-6. doi: 10.1021/acs.jpcb.5b04202. Epub 2015 Jul 10.
Three series of multicomponent silicone hydrogels were prepared by the copolymerization of two hydrophobic silicon monomers bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate (SiMA) and tris(trimethylsiloxy) 3-methacryloxypropylsilane (TRIS) with three hydrophilic monomers. The surface hydrophilicity of the silicone hydrogels was characterized by contact angle measurements, and an interesting phenomenon was found that the silicone hydrogels made from less hydrophobic monomer SiMA possess more hydrophobic surfaces than those made from TRIS. The surface properties such as morphology and elemental composition of the silicone hydrogels were explored by scanning electron microscopy (SEM) imaging and energy dispersive spectrometry (EDS) analysis, and their relationships with the surface hydrophilicity were investigated in details. The results show neither the surface morphology nor the elemental composition has obvious impact on the surface hydrophilicity. Atomic force microscopy (AFM) imaging revealed that SiMA hydrogel had a more significant phase separation structure, which also made its surface uneven: a lot of tiny holes were observed on the surface. This surface phase separation structure made SiMA hydrogel more difficult to be wetted by water or PBS buffer, i.e., more hydrophobic than TRIS hydrogel. On the basis of these results, we propose that the phase separation structure as well as the nature of silicon monomers might be the fundamental reasons of surface hydrophilicity. These results could help to design a silicone hydrogel with better surface properties and wider application.
通过两种疏水性硅单体双（三甲基硅氧基）甲基硅丙基甘油甲基丙烯酸酯（SiMA）和三（三甲基硅氧基）3 - 甲基丙烯酰氧基丙基硅烷（TRIS）与三种亲水性单体的共聚反应，制备了三个系列的多组分硅水凝胶。通过接触角测量对硅水凝胶的表面亲水性进行了表征，发现了一个有趣的现象：由疏水性较低的单体SiMA制成的硅水凝胶比由TRIS制成的具有更疏水的表面。通过扫描电子显微镜（SEM）成像和能量色散光谱（EDS）分析探索了硅水凝胶的表面形态和元素组成等表面性质，并详细研究了它们与表面亲水性的关系。结果表明，表面形态和元素组成对表面亲水性均无明显影响。原子力显微镜（AFM）成像显示，SiMA水凝胶具有更显著的相分离结构，这也使其表面不平坦：在表面观察到许多小孔。这种表面相分离结构使得SiMA水凝胶更难被水或PBS缓冲液润湿，即比TRIS水凝胶更疏水。基于这些结果，我们提出相分离结构以及硅单体的性质可能是表面亲水性的根本原因。这些结果有助于设计具有更好表面性质和更广泛应用的硅水凝胶。
