Krasnov Igor, Seydel Tilo, Greving Imke, Blankenburg Malte, Vollrath Fritz, Müller Martin
Institut für Experimentelle und Angewandte Physik, Universität Kiel, 24098 Kiel, Germany Institute of Materials Research, Helmholtz-Zentrum Geesthacht (HZG), 21502 Geesthacht, Germany.
Institut Max von Laue-Paul Langevin (ILL), CS 20156, 38042 Grenoble, France
J R Soc Interface. 2016 Sep;13(122). doi: 10.1098/rsif.2016.0506.
Spider silk is a material well known for its outstanding mechanical properties, combining elasticity and tensile strength. The molecular mobility within the silk's polymer structure on the nanometre length scale importantly contributes to these macroscopic properties. We have therefore investigated the ensemble-averaged single-particle self-dynamics of the prevailing hydrogen atoms in humid spider dragline silk fibres on picosecond time scales in situ as a function of an externally applied tensile strain. We find that the molecular diffusion in the amorphous fraction of the oriented fibres can be described by a generalized fractional diffusion coefficient Kα that is independent of the observation length scale in the probed range from approximately 0.3-3.5 nm. Kα increases towards a diffusion coefficient of the classical Fickian type with increasing tensile strain consistent with an increasing loss of memory or entropy in the polymer matrix.
蜘蛛丝是一种以其出色的机械性能而闻名的材料，兼具弹性和拉伸强度。丝聚合物结构内纳米长度尺度上的分子运动性对这些宏观性能起着重要作用。因此，我们研究了在皮秒时间尺度上，作为外部施加拉伸应变的函数，潮湿蜘蛛拖丝纤维中主要氢原子的系综平均单粒子自动力学。我们发现，取向纤维非晶部分的分子扩散可以用一个广义分数扩散系数Kα来描述，该系数在约0.3 - 3.5纳米的探测范围内与观测长度尺度无关。随着拉伸应变的增加，Kα朝着经典菲克型扩散系数增加，这与聚合物基质中记忆或熵的损失增加一致。
