Microbeads and hollow microcapsules obtained by self-assembly of pickering magneto-responsive cellulose nanocrystals.
Microbeads and hollow microcapsules obtained by self-assembly of pickering magneto-responsive cellulose nanocrystals.
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DOI：
10.1021/am504260u
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发表时间：
2014-09
影响因子：
9.5
通讯作者：
Tiina Nypelö;C. Rodríguez‐Abreu;Yury V. Kolen’ko;J. Rivas;O. Rojas
中科院分区：
文献类型：
--
作者：
Tiina Nypelö;C. Rodríguez‐Abreu;Yury V. Kolen’ko;J. Rivas;O. Rojas
纤维素微珠可用作固定化载体。本文报道了一种各向同性和各向异性纳米材料的混合物——纤维素纳米晶体（CNC）自组装壳携带磁性CoFe2O4纳米粒子，设计和制备了磁响应纤维素微珠和微胶囊。磁性碳纳米管形成了一个结构层，一个网格，由碳纳米管和磁性颗粒结合在一起，在分散在水中的十六烷和苯乙烯的不同液滴表面。由于cnc的存在，与整齐的聚合物外壳相比，高度结晶的网状结构提供了微珠外壳更好的阻隔性能，而磁性颗粒提供了磁响应。苯乙烯相的原位聚合导致形成固体微珠（直径约8 μm），由包裹在磁性CNC外壳中的聚苯乙烯（PS）芯组成（壳核质量比为4:96）。所得固体微珠具有铁磁性（每克磁相的饱和磁化强度为~ 60 emu）。磁性功能使固定在珠子上的物质易于分离。这种功能在去除水中染料的过程中得到了测试。进一步利用微球对PS核进行增溶制备空心微胶囊。利用电子显微镜（形貌）、x射线衍射（相组成）和磁强计（磁性能）表征了基于cnc的磁响应固体微珠和空心微胶囊。这种混合系统可用于设计用于胶体稳定、浓缩、分离和输送等方面的材料和设备。
Cellulose microbeads can be used as immobilization supports. We report on the design and preparation of magneto-responsive cellulose microbeads and microcapsules by self-assembled shells of cellulose nanocrystals (CNC) carrying magnetic CoFe2O4 nanoparticles, that is, a mixture of isotropic and anisotropic nanomaterials. The magnetic CNCs formed a structured layer, a mesh, consisting of CNCs and magnetic particles bound together on the surface of distinct droplets of hexadecane and styrene dispersed in water. Because of the presence of CNCs the highly crystalline mesh was targeted to provide an improved barrier property of the microbead shell compared to neat polymer shells, while the magnetic particles provided the magnetic response. In situ polymerization of the styrene phase led to the formation of solid microbeads (∼8 μm diameter) consisting of polystyrene (PS) cores encapsulated in the magnetic CNC shells (shell-to-core mass ratio of 4:96). The obtained solid microbeads were ferromagnetic (saturation magnetization of ∼60 emu per gram of the magnetic phase). The magnetic functionality enables easy separation of substances immobilized on the beads. Such a functionality was tested in removal of a dye from water. The microbeads were further utilized to synthesize hollow microcapsules by solubilization of the PS core. The CNC-based, magneto-responsive solid microbeads and hollow microcapsules were characterized by electron microscopy (morphology), X-ray diffraction (phase composition), and magnetometry (magnetic properties). Such hybrid systems can be used in the design of materials and devices for application in colloidal stabilization, concentration, separation, and delivery, among others.