One-Pot Synthesis of Block Copolymers in Supercritical Carbon Dioxide: A Simple Versatile Route to Nanostructured Microparticles
One-Pot Synthesis of Block Copolymers in Supercritical Carbon Dioxide: A Simple Versatile Route to Nanostructured Microparticles
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DOI：
10.1021/ja210577h
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发表时间：
2012-03-14
影响因子：
15
通讯作者：
Howdle, Steven M.
中科院分区：
文献类型：
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作者：
Jennings, James;Beija, Mariana;Howdle, Steven M.
我们提出了一种一锅法合成明确的纳米结构的聚合物微粒形成的嵌段共聚物，可以很容易地适应于商业规模。我们已经利用可逆加成-断裂链转移（RAFT）聚合在超临界二氧化碳中的分散聚合中制备嵌段共聚物，这是一种不使用额外溶剂的有效方法，因此是环境可接受的。我们证明了可以利用广泛的单体类型，包括甲基丙烯酸酯、丙烯酰胺和苯乙烯类，从而产生两亲性的嵌段共聚物材料（例如，聚（甲基丙烯酸甲酯）-b-聚（N，N-二甲基丙烯酰胺））和/或机械上不同的（例如，聚（甲基丙烯酸甲酯）-b-聚（甲基丙烯酸N，N-二甲氨基乙酯））。询问的微粒的内部结构揭示了一系列的纳米级形态，包括多层，弯曲的圆柱形，球形域。令人惊讶的是，还可以通过改变组成嵌段的化学性质来进行控制，并且很明显，选择性的CO2吸附必须强烈影响嵌段共聚物的相行为，导致动力学捕获的形态与通常观察到的嵌段共聚物薄膜不同。在不存在CO2的情况下。
We present a one-pot synthesis for well-defined nanostructured polymeric microparticles formed from block copolymers that could easily be adapted to commercial scale. We have utilized reversible addition-fragmentation chain transfer (RAFT) polymerization to prepare block copolymers in a dispersion polymerization in supercritical carbon dioxide, an efficient process which uses no additional solvents and hence is environmentally acceptable. We demonstrate that a wide range of monomer types, including methacrylates, acrylamides, and styrenics, can be utilized leading to block copolymer materials that are amphiphilic (e.g., poly(methyl methacrylate)-b-poly(N,N-dimethylacrylamide)) and/or mechanically diverse (e.g., poly(methyl methacrylate)-b-poly(N,N-dimethylaminoethylmethacrylate)). Interrogation of the internal structure of the microparticles reveals an array of nanoscale morphologies, including multilayered, curved cylindrical, and spherical domains. Surprisingly, control can also be exerted by changing the chemical nature of the constituent blocks and it is clear that selective CO2 sorption must strongly influence the block copolymer phase behavior, resulting in kinetically trapped morphologies that are different from those conventionally observed for block copolymer thin films formed in absence of CO2.