Department of Chemical Engineering, Graduate School of Engineering, Tohoku University 6-6-07 Aoba, Aramaki-aza Aoba-ku, Sendai, 980-8579, Japan.
Langmuir. 2010 Apr 6;26(7):5208-12. doi: 10.1021/la903673j.
Hollow asymmetrical silica dumbbells containing a movable inner core were fabricated by a template-assisted method. Three different templates were employed for the fabrication of the hollow asymmetrical dumbbells. For the preparation of the first template, silica particles were uniformly covered with a cross-linked polymethylmethacrylate (PMMA) shell and the polymerization of styrene was conducted to induce a protrusion of polystyrene (PSt) from the PMMA shell. Anisotropic colloids composed of silica, PMMA, and PSt were used as templates, coated with a silica shell, and held at 500 degrees C for 2 h to remove the polymer interior components of the template colloid. The heat treatment successfully produced hollow asymmetrical silica dumbbells containing an inner silica core. After being dried, approximately 50% of the inner silica particles that were originally coated with PMMA ended up in the other hollow sphere in which the PSt component existed before heat treatment, indicating that the inner silica particles could pass through the hollow asymmetrical dumbbells' necks and were free to move in the interior. In the preparation of the second and third asymmetrical dumbbell templates, magnetic silica particles and titania particles, respectively, were covered with a PMMA shell to incorporate externally responsive particles into the hollow silica shells as above. The successful syntheses demonstrated the generality of our approach. The passage of the responsive particles through the dumbbell's neck enabled active control of the position of the responsive particles inside the asymmetrical dumbbells by external fields.
采用模板辅助法制备了含有可动内核的中空不对称硅哑铃。使用了三种不同的模板来制备中空不对称哑铃。为了制备第一个模板，二氧化硅颗粒均匀地覆盖有交联的聚甲基丙烯酸甲酯（PMMA）壳，然后进行苯乙烯聚合，以诱导聚苯乙烯（PSt）从 PMMA 壳中突出。由二氧化硅、PMMA 和 PSt 组成的各向异性胶体被用作模板，用二氧化硅壳包裹，并在 500°C 下保持 2 小时，以去除模板胶体的聚合物内部成分。热处理成功地产生了含有内部二氧化硅核的中空不对称硅哑铃。干燥后，大约 50%的最初用 PMMA 涂覆的内部二氧化硅颗粒最终进入另一个空心球体，其中存在热处理前的 PSt 成分，表明内部二氧化硅颗粒可以穿过中空不对称哑铃的颈部，并在内部自由移动。在制备第二和第三个不对称哑铃模板时，分别用 PMMA 壳覆盖磁性二氧化硅颗粒和二氧化钛颗粒，如上所述将对外界响应的颗粒纳入中空硅壳中。成功的合成证明了我们方法的通用性。响应性颗粒通过哑铃的颈部，使外部场能够主动控制不对称哑铃内部响应性颗粒的位置。
