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Temperature-Induced Formation of Uniform Polymer Nanocubes Directly in Water.
Biomacromolecules ( IF 5.5 ) Pub Date : 2020-01-16 , DOI: 10.1021/acs.biomac.9b01637
Carlos Fitzgerald Grandes Reyes 1 , Sung-Po R Chen 1 , Valentin A Bobrin 1 , Zhongfan Jia 1 , Michael J Monteiro 1
Affiliation  

Conventional self-assembly methods of block copolymers in cosolvents (i.e., usually water and organic solvents) has yet to produce a pure and monodisperse population of nanocubes. The requirement to assemble a nanocube is for the second block to have a high molecular weight. However, such high molecular weight block copolymers usually result in the formation of kinetically trapped nanostructures even with the addition of organic cosolvents. Here, we demonstrate the rapid production of well-defined polymer nanocubes directly in water by utilizing the thermoresponsive nature of the second block (with 263 monomer units), in which the block copolymer was fully water-soluble below its lower critical solution temperature (LCST) and would produce a pure population of nanocubes when heated above this temperature. Incorporating a pH-responsive monomer in the second block allowed us to control the size of the nanocubes in water with pH and the LCST of the block copolymer. We then used the temperature and pH responsiveness to create an adaptive system that changes morphology when using a unique fuel. This fuel (H2O2 + MnO2) is highly exothermic, and the solution pH increases with the consumption of H2O2. Initially, a nonequilibrium spherical nanostructure formed, which transformed over time into nanocubes, and by controlling the exotherm of the reaction, we controlled the time for this transformation. This block copolymer and the water-only method of self-assembly have provided some insights into designing biomimetic systems that can readily adapt to the environmental conditions.

中文翻译:

温度诱导的均匀聚合物纳米立方体直接在水中形成。

在共溶剂(即通常为水和有机溶剂)中的嵌段共聚物的常规自组装方法尚未产生纯且单分散的纳米立方体。组装纳米立方体的要求是第二嵌段具有高分子量。然而,即使添加有机助溶剂,这种高分子量嵌段共聚物通常也导致形成动力学捕获的纳米结构。在这里,我们证明了利用第二个嵌段(具有263个单体单元)的热响应特性,可以直接在水中直接快速生产定义明确的聚合物纳米立方体,其中嵌段共聚物在低于其较低的临界溶液温度(LCST)时是完全水溶性的),并在高于该温度时会产生纯的纳米立方体。在第二个嵌段中加入pH响应性单体使我们能够控制pH值和嵌段共聚物的LCST,从而控制水中纳米立方体的尺寸。然后,我们使用温度和pH响应性来创建一个自适应系统,该系统在使用独特燃料时会改变形态。该燃料(H2O2 + MnO2)放热性很高,溶液的pH随着H2O2的消耗而增加。最初,形成了一个非平衡球形纳米结构,该结构随时间转变为纳米立方体,并且通过控制反应的放热,我们控制了该转变的时间。这种嵌段共聚物和仅水的自组装方法为设计仿生系统提供了一些见识,该仿生系统可以轻松适应环境条件。
更新日期:2020-01-08
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