About ten years ago, chemically fueled systems have emerged as a new class of synthetic materials with tunable properties. Yet, applications of these materials are still scarce. In part, this is due to an incomplete characterization of the viscoelastic properties of those materials, which has – so far – mostly been limited to assessing their linear response under shear load. Here, we fill some of these gaps by comparing the viscoelastic behavior of two different, carbodiimide fueled Fmoc-peptide systems. We find that both, the linear and non-linear response of the hydrogels formed by those Fmoc-peptides depends on the amount of fuel driving the self-assembly process – but hardly on the direction of force application. In addition, we identify the concentration of accumulated waste products as a novel, so far neglected parameter that crucially affects the behavior of such chemically fueled hydrogels. With the mechanistic insights gained here, it should be possible to engineer a new generation of dynamic hydrogels with finely tunable material properties that can be tailored precisely for such applications, where they are challenged by mechanical forces.

大约十年前，化学燃料系统已经成为一类具有可调特性的新型合成材料。然而，这些材料的应用仍然很少。在某种程度上，这是由于对这些材料的粘弹性特性的不完整表征——到目前为止——主要限于评估它们在剪切载荷下的线性响应。在这里，我们通过比较两种不同的碳二亚胺驱动的 Fmoc 肽系统的粘弹性行为来填补其中的一些空白。我们发现，由这些 Fmoc 肽形成的水凝胶的线性和非线性响应都取决于驱动自组装过程的燃料量——但几乎不取决于力的施加方向。此外，我们将累积废物的浓度确定为一种新颖的、到目前为止，忽略了对这种化学燃料水凝胶的行为产生关键影响的参数。有了这里获得的机械洞察力，应该有可能设计出具有精细可调材料特性的新一代动态水凝胶，这些特性可以为此类应用精确定制，在这些应用中它们受到机械力的挑战。