Uncontrolled polymerization that occurred during photoinitiated RAFT dispersion polymerization of acrylic monomers promotes the formation of uniform raspberry-like polymer particles
Uncontrolled polymerization that occurred during photoinitiated RAFT dispersion polymerization of acrylic monomers promotes the formation of uniform raspberry-like polymer particles
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DOI：
10.1039/d0py00678e
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发表时间：
2020-07
影响因子：
4.6
通讯作者：
Ruiming Zeng;Ying Chen;Li Zhang;Jianbo Tan
中科院分区：
文献类型：
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作者：
Ruiming Zeng;Ying Chen;Li Zhang;Jianbo Tan
在典型的可逆加成-断裂链转移(RAFT)介导的分散聚合中，良好的RAFT控制通常是不可避免的。这一特性导致了嵌段共聚物的形成，这些嵌段共聚物的分散性很低，并且形成了定义良好的嵌段共聚纳米对象。在这项研究中，报道了一种不同类型的RAFT介导的丙烯酸酯单体分散聚合反应，该聚合反应的基础是RAFT控制和光引发性能差。在这种情况下，形成了均匀的覆盆子状聚合物颗粒，而不是定义良好的嵌段共聚纳米对象。凝胶渗透色谱(GPC)测试表明，在光引发RAFT分散聚合过程中，生成了大量不含RAFT基团的非受控聚合物，促进了树莓状聚合物粒子的形成。通过在不同的时间间隔提取样品，发现树莓状聚合物粒子是由小的聚合物粒子附着在大的光滑的聚合物粒子表面形成的。对照实验表明，聚二丙酮丙烯酰胺(PDAAM)基大分子RAFT试剂的使用和丙烯酸异丁酯(IBOA)成核单体的使用都是这种不寻常的光引发RAFT分散聚合的关键。我们期望这项研究不仅为一步制备高固含量的均匀树莓状聚合物粒子提供一种简便的方法，还将为光引发RAFT介导的分散聚合的机理提供更多的见解。
In a typical reversible addition–fragmentation chain transfer (RAFT)-mediated dispersion polymerization, good RAFT control is usually inevitable. This characteristic leads to the formation of block copolymers with low dispersities and well-defined block copolymer nano-objects. In this study, a different type of RAFT-mediated dispersion polymerization of acrylic monomers based on poor RAFT control and photoinitiation is reported. Uniform raspberry-like polymer particles rather than well-defined block copolymer nano-objects were formed in the present case. Gel permeation chromatography (GPC) measurement indicated that a noticeable amount of uncontrolled polymers without RAFT groups was generated during the photoinitiated RAFT dispersion polymerization, promoting the formation of uniform raspberry-like polymer particles. By extracting samples at different time intervals, it was found that raspberry-like polymer particles were formed by the adhesion of small polymer particles to the surface of large smooth polymer particles. Controlled experiments demonstrated that both the use of a poly(diacetone acrylamide) (PDAAM)-based macro-RAFT agent and the use of an isobronyl acrylate (IBOA) core-forming monomer were critical for this unusual photoinitiated RAFT dispersion polymerization. We expect that this study will not only provide a facile method for the preparation of uniform raspberry-like polymer particles at high solid contents in a single step, but also provide more insights into the mechanism of photoinitiated RAFT-mediated dispersion polymerization.