Hypothesis

Hollow nanospheres, characterized by a cavity inside a solid shell, have potential applications due to their unique structure, but the unchangeable morphology and permeability of the shell restrain their further practical utilization. While several smart hollow nanospheres that can respond to pH, ion strength, and temperature have been developed, they are inclined to suffer from problems associated with high energy consumption or the difficult removal of residual stimulants. Thus, it is desirable to develop a novel and free-of-residual trigger stimulating mode.

Experiments

In this work, CO₂ is used to fabricate smart hollow nanospheres composed of crosslinked poly(diethylamino-ethyl methacrylate) (PDEAEMA) network from polystyrene (PS)/PDEAEMA core-shell nanospheres by a template-removal technique. The morphology evolution of the resultant nanospheres during the fabrication process was characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA) and dynamic light scattering (DLS) and was visualized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM).

Findings

Hollow nanospheres can be generated by experiencing a morphology change from a core nanosphere, core-shell, yolk-shell to a final hollow structure. The increase in shell-stiffness can restrain the collapse of hollow spheres. It is demonstrated that CO₂ is easy to introduce and remove (via N₂ input) without stimulation residues in this system. In addition, mild CO₂/N₂ purging can only reversibly change the swelling/collapse of hollow particles; violent CO₂/N₂ bubbling can reversibly regulate both the size and aggregation/re-dispersion state of the hollow nanospheres, which can be intuitively observed by atomic force microscopy (AFM).

中文翻译：

---

CO ₂可切换中空纳米球

假设

空心纳米球的特征是在固体壳内部具有空腔，由于其独特的结构而具有潜在的应用前景，但壳的形态和渗透性不变，限制了它们的进一步实际应用。虽然已经开发出了几种可以响应pH，离子强度和温度的智能空心纳米球，但它们倾向于承受与高能耗或难以去除残留刺激物有关的问题。因此，期望开发一种新颖且无残留的触发刺激模式。

实验

在这项工作中，CO ₂用于通过模板去除技术从聚苯乙烯（PS）/ PDEAEMA核壳纳米球制备由交联的聚（二乙氨基乙基甲基丙烯酸乙酯）（PDEAEMA）网络组成的智能空心纳米球。通过X射线光电子能谱（XPS），傅立叶变换红外光谱（FTIR），热重分析（TGA）和动态光散射（DLS）表征了制造过程中所得纳米球的形貌演变，并通过透射电子显微镜进行了可视化（TEM）和扫描电子显微镜（SEM）。

发现

空心纳米球可以通过经历从核纳米球，核-壳，蛋黄-壳到最终的中空结构的形态变化而产生。壳刚度的增加可以抑制空心球的塌陷。已经证明，在该系统中，CO ₂易于引入和去除（通过N ₂输入），而没有刺激性残留物。另外，温和的CO ₂ / N ₂吹扫只能可逆地改变空心颗粒的溶胀/塌陷。剧烈的CO ₂ / N ₂鼓泡可以可逆地调节中空纳米球的大小和聚集/再分散状态，这可以通过原子力显微镜（AFM）直观地观察到。