Dynamic transformations of self-assembled polymeric microspheres induced by AC voltage and shear flow
Dynamic transformations of self-assembled polymeric microspheres induced by AC voltage and shear flow
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DOI：
10.1039/c4ra17056c
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发表时间：
2015-01
期刊：
影响因子：
3.9
通讯作者：
N. Morimoto;T. Wazawa;Y. Inoue;Makoto Suzuki
中科院分区：
文献类型：
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作者：
N. Morimoto;T. Wazawa;Y. Inoue;Makoto Suzuki
为了控制聚乙二醇胺丙磺酸盐(glycol)-block-poly(3-dimethyl(methacryloyloxyethyl)-SB)在水溶液中的动态转变，对由双亲水嵌段共聚物聚乙二醇胺丙磺酸盐(PEGSB)组成的自组装多层微球施加交流电压和剪切流。在交流电压作用下，接触加速了MLM的熔融，其尺寸从∼1.5μm增大到几十μm，生长速度可以通过改变SB单元的频率和聚合度来控制。熔融传质材料在密闭腔体中发生爆裂，其平均尺寸为25μm。另一方面，在剪切流量大于1.5×10~3 S−1的条件下，熔融传质材料也可以被熔化。当剪切流被移除时，弦状结构分裂成MLM。MLMS的这种多重动态转化可应用于各种液滴，如全水液滴微流体中的微货物、微反应器和微分离器。
AC voltage and shear flow are applied to self-assembled, multi-layered microspheres (MLMs) composed of a double hydrophilic block copolymer, poly(ethylene glycol)-block-poly(3-dimethyl(methacryloyloxyethyl) ammoniumpropane sulfonate), (PEG-SB) in order to control dynamic transformations in aqueous solution. Under application of AC voltage, the fusion of MLMs is accelerated by contact and the size grows from ∼1.5 μm to several tens of μm. The rate of growth is controllable by varying the frequency and the polymerization degree of the SB unit. Bursting of the fused MLMs is induced in a closed chamber and the average size of the bursting MLMs is 25 μm. On the other hand, MLMs are also fused under shear flow above 1.5 × 103 s−1. The fused MLMs grow to be a string-like structure with a length of more than 4 cm and the aspect ratio of >4000. The string-like structure splits into MLMs when the shear flow is removed. Such multiple dynamic transformations of MLMs can be applied to versatile droplets as microcargoes, microreactors, and microseparators in fully aqueous droplet microfluidics.