The viscoelastic properties of filaments and biopolymers play a crucial role in soft and biological materials from biopolymer networks to novel synthetic metamaterials. Colloidal particles with specific valency allow mimicking polymers and more complex molecular structures at the colloidal scale, offering direct observation of their internal degrees of freedom. Here, we elucidate the time-dependent viscoelastic response in the bending of isolated semi-flexible colloidal polymers, assembled from dipatch colloidal particles by reversible critical Casimir forces. By tuning the patch–patch interaction strength, we adjust the polymers' viscoelastic properties, and follow spontaneous bending modes and their relaxation directly on the particle level. We find that the elastic response is well described by that of a semiflexible rod with persistence length of order 1000 μm, tunable by the critical Casimir interaction strength. We identify the viscous relaxation on longer timescales to be due to internal friction, leading to a wavelength-independent relaxation time similar to single biopolymers, but in the colloidal case arising from the contact mechanics of the bonded patches. These tunable mechanical properties of assembled colloidal filaments open the door to “colloidal architectures”, rationally designed (network) structures with desired topology and mechanical properties.

中文翻译：

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揭示孤立的半柔性胶体聚合物的粘弹性弯曲松弛动力学

长丝和生物聚合物的粘弹性在从生物聚合物网络到新型合成超材料的软和生物材料中起着至关重要的作用。具有特定价态的胶体粒子可以在胶体尺度上模拟聚合物和更复杂的分子结构，从而直接观察它们的内部自由度。在这里，我们阐明了孤立的半柔性胶体聚合物弯曲时随时间变化的粘弹性响应，这些聚合物是通过可逆临界卡西米尔力由二段胶体颗粒组装而成的。通过调整贴片-贴片相互作用强度，我们调整了聚合物的粘弹性，并直接在粒子水平上遵循自发弯曲模式及其松弛。我们发现弹性响应可以通过具有 1000 μm 数量级持久长度的半柔性杆来很好地描述，可通过临界 Casimir 相互作用强度进行调节。我们确定较长时间尺度上的粘性松弛是由于内部摩擦，导致类似于单个生物聚合物的波长独立松弛时间，但在胶体情况下是由粘合贴片的接触力学引起的。组装胶体长丝的这些可调机械性能为“胶体结构”打开了大门，合理设计的（网络）结构具有所需的拓扑结构和机械性能。导致类似于单一生物聚合物的波长独立弛豫时间，但在胶体情况下是由粘合贴片的接触力学引起的。组装胶体长丝的这些可调机械性能为“胶体结构”打开了大门，合理设计的（网络）结构具有所需的拓扑结构和机械性能。导致类似于单一生物聚合物的波长独立弛豫时间，但在胶体情况下是由粘合贴片的接触力学引起的。组装胶体长丝的这些可调机械性能为“胶体结构”打开了大门，合理设计的（网络）结构具有所需的拓扑结构和机械性能。