Mhanna Ramona, Gao Yan, Van Tol Isaac, Springer Ela, Wu Ning, Marr David W M
Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado 80401, United States.
Langmuir. 2022 May 10;38(18):5730-5737. doi: 10.1021/acs.langmuir.2c00343. Epub 2022 Apr 29.
Magnetic colloidal chains are a microrobotic system with promising applications due to their versatility, biocompatibility, and ease of manipulation under magnetic fields. Their synthesis involves kinetic pathways that control chain quality, length, and flexibility, a process performed by first aligning superparamagnetic particles under a one-dimensional magnetic field and then chemically linking them using a four-armed maleimide-functionalized poly(ethylene glycol). Here, we systematically vary the concentration of the poly(ethylene glycol) linkers, the reaction temperature, and the magnetic field strength to study their impact on the physical properties of synthesized chains, including the chain length distribution, reaction temperature, and bending modulus. We find that this chain fabrication process resembles step-growth polymerization and can be accurately described by the Flory-Schulz model. Under optimized experimental conditions, we have successfully synthesized long flexible colloidal chains with a bending modulus, which is 4 orders of magnitude smaller than previous studies. Such flexible and long chains can be folded entirely into concentric rings and helices with multiple turns, demonstrating the potential for investigating the actuation, assembly, and folding behaviors of these colloidal polymer analogues.
磁性胶体链是一种微型机器人系统，因其多功能性、生物相容性以及在磁场下易于操作而具有广阔的应用前景。它们的合成涉及控制链质量、长度和柔韧性的动力学途径，该过程首先在一维磁场下对齐超顺磁性颗粒，然后使用四臂马来酰亚胺功能化聚乙二醇对其进行化学连接。在此，我们系统地改变聚乙二醇连接剂的浓度、反应温度和磁场强度，以研究它们对合成链物理性质的影响，包括链长分布、反应温度和弯曲模量。我们发现这种链的制造过程类似于逐步增长聚合，并且可以用弗洛里 - 舒尔茨模型准确描述。在优化的实验条件下，我们成功合成了具有弯曲模量的长柔性胶体链，该弯曲模量比先前的研究小4个数量级。这种柔性长链可以完全折叠成具有多圈的同心环和螺旋，展示了研究这些胶体聚合物类似物的驱动、组装和折叠行为的潜力。
