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Influence of structure and solubility of chain transfer agents on the RAFT control of dispersion polymerisation in scCO2
Chemical Science ( IF 7.6 ) Pub Date : 2020-11-17 , DOI: 10.1039/d0sc05281g
Ana A C Pacheco 1 , Arnaldo F da Silva Filho 1 , Kristoffer Kortsen 1 , Magnus W D Hanson-Heine 1 , Vincenzo Taresco 1 , Jonathan D Hirst 1 , Muriel Lansalot 2 , Franck D'Agosto 2 , Steven M Howdle 1
Affiliation  

Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerisation of methyl methacrylate (MMA) is performed in supercritical carbon dioxide (scCO2) with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) present as chain transfer agent (CTA) and surprisingly shows good control over PMMA molecular weight. Kinetic studies of the polymerisation in scCO2 also confirm these data. By contrast, only poor control of MMA polymerisation is obtained in toluene solution, as would be expected for this CTA which is better suited for acrylates. In this regard, we select a range of CTAs and use them to determine the parameters that must be considered for good control in dispersion polymerisation in scCO2. A thorough investigation of the nucleation stage during the dispersion polymerisation reveals an unexpected “in situ two-stage” mechanism that strongly determines how the CTA works. Finally, using a novel computational solvation model, we identify a correlation between polymerisation control and degree of solubility of the CTAs. All of this ultimately gives rise to a simple, elegant and counterintuitive guideline to select the best CTA for RAFT dispersion polymerisation in scCO2.

中文翻译:


链转移剂的结构和溶解度对 scCO2 中分散聚合的 RAFT 控制的影响



甲基丙烯酸甲酯(MMA)的可逆加成-断裂链转移(RAFT)分散聚合在超临界二氧化碳(scCO 2 )中进行,2-(十二烷基硫代碳硫酰硫基)-2-甲基丙酸(DDMAT)作为链转移剂(CTA)和令人惊讶的是,它显示出对 PMMA 分子量的良好控制。 scCO 2中聚合的动力学研究也证实了这些数据。相比之下,在甲苯溶液中只能对 MMA 聚合进行较差的控制,正如对于这种更适合丙烯酸酯的 CTA 所预期的那样。在这方面,我们选择了一系列 CTA 并使用它们来确定在 scCO 2中良好控制分散聚合时必须考虑的参数。对分散聚合过程中成核阶段的彻底研究揭示了一种意想不到的“原位两阶段”机制,它在很大程度上决定了 CTA 的工作原理。最后,使用一种新颖的计算溶剂化模型,我们确定了聚合控制和 CTA 溶解度之间的相关性。所有这些最终产生了一个简单、优雅且违反直觉的指南,用于选择 scCO 2中 RAFT 分散聚合的最佳 CTA。
更新日期:2020-11-25
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