Mechanical properties of robust ultrathin silk fibroin films
Mechanical properties of robust ultrathin silk fibroin films
复制标题
DOI：
10.1002/adfm.200601136
复制
发表时间：
2007-09-03
影响因子：
19
通讯作者：
Tsukruk, Vladimir V.
中科院分区：
文献类型：
--
作者：
Jiang, Chaoyang;Wang, Xianyan;Tsukruk, Vladimir V.
通过旋涂和旋辅助逐层组装制备了坚韧的丝素蛋白超薄多层膜，并首次在拉伸和压缩模式下研究了它们的力学性能。这些超薄膜的特征在于具有6 - 8吉帕（用甲醇处理后）的高弹性模量，极限拉伸强度达到兆帕。其优异的韧性比常规聚合物复合材料通常所观察到的要高数倍（此处所研究的丝材料为328千焦/立方米，而典型值＜100千焦/立方米）。这些出色的性能被认为是由高度结晶的β - 折叠的自增强微观结构逐渐形成所导致的，β - 折叠起到增强填料和物理交联的作用，这一过程对于块状丝材料是众所周知的，但在此处也证明在超薄膜中同样会发生，尽管其尺寸有限。然而，在比延伸区域长度更薄的膜内的受限状态导致弹性显著降低，这在由丝材料设计纳米尺寸的膜时应予以考虑。这种具有出色机械强度的再生丝纤维在微尺度薄膜生物器件、生物相容性植入物以及人造皮肤的合成涂层方面具有潜在应用。
Robust ultrathin multilayer films of silk fibroin were fabricated by spin coating and spin-assisted layer-by-layer assembly and their mechanical properties Were studied both in tensile and compression modes for the first time. The ultrathin films were characterized by a high elastic modulus of 6-8 GPa- (after treatment with methanol) with the ultimate tensile strength reaching MPa. The superior toughness is times higher than that usually observed for conventional, polymer composites (328 kJ m(-3) for the silk material studied, here versus typical values of < 100 kJ m(-3)). These outstanding properties are suggested to be caused by the gradual development of the self-reinforcing microstructure of highly crystalline beta-sheets, serving as reinforcing fillers and physical crosslinks, a process that is well known for bulk silk materials but it is demonstrated here to occur in ultrathin films as well, despite their limited dimensions. However, the confined state within films thinner than the lengths of the extended domains causes a significantly reduced elasticity which should be considered in the design of nanosized films from silk materials. Such regenerated silk fibrbirt with outstanding mechanical strength have potential applications in microscale films biodevices, biocompatible implants, and synthetic coatings for artificial skin.