ATRP 和 RAFT 的自发梯度：可互换的聚合方法？,Macromolecules

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ATRP 和 RAFT 的自发梯度：可互换的聚合方法？
Macromolecules ( IF 5.1 ) Pub Date : 2023-10-27 , DOI: 10.1021/acs.macromol.3c01426
Kate G. E. Bradford ₁ , Robert D. Gilbert ₁ , M. A. Sachini N. Weerasinghe ₁ , Simon Harrisson ₂ , Dominik Konkolewicz ₁

Affiliation

通过 ATRP 和 RAFT 研究了自发梯度聚合。两个体系的模型单体均为甲基丙烯酸甲酯 (MMA) 和丙烯酸乙酯 (EA)。生成自发梯度聚合物；然而，对聚合物结构的控制随聚合方法和引发剂结构的不同而变化。研究发现，使用与甲基丙烯酸和丙烯酸单体均相容的链转移剂 (CTA) 时，RAFT 聚合具有最佳控制效果。使用这种双重相容的 CTA 可以实现高效的 RAFT 聚合，并提供实验和理论分子量的良好相关性、低于 1.3 的分散度以及与自发梯度形成一致的反应率。相比之下，具有不太有效的均裂离去基团的 RAFT CTA 导致实验和理论分子量和分散度之间的相关性较差，通常高于 1.5。一般来说，ATRP 导致聚合物分散度较高，约为 1.4-1.5，尽管形成了梯度，但实验和理论分子量的相关性降低。MMA 和 EA 的反应率均通过使用末端反应模型确定。由于增长自由基相同，反应率与传统自由基聚合中的反应率相似。尽管相似，但 RAFT 和 ATRP 在梯度聚合中不能完全互换，当选择与两种单体兼容的 CTA 时，RAFT 提供了一种更简单的梯度聚合物方法。

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Spontaneous Gradients by ATRP and RAFT: Interchangeable Polymerization Methods?

The spontaneous gradient polymerization was investigated by ATRP and RAFT. The model monomers for both systems were methyl methacrylate (MMA) and ethyl acrylate (EA). Spontaneous gradient polymers were generated; however, the control over a polymer structure varied with both the polymerization method and the initiator structure. RAFT polymerization was found to have the best control while using a chain transfer agent (CTA) compatible with both the methacrylic and acrylic monomers. The use of this dual compatible CTA allowed for efficient RAFT polymerization and gave excellent correlation of experimental and theoretical molecular weights, dispersities below 1.3, and reactivity ratios consistent with spontaneous gradient formation. In contrast, the RAFT CTA with a less effective homolytic leaving group led to poor correlation between experimental and theoretical molecular weights and dispersity typically above 1.5. In general, ATRP led to somewhat higher dispersity polymers in the order of 1.4–1.5 with decreased correlation of experimental and theoretical molecular weights despite the formation of gradients. Reactivity ratios for both MMA and EA were determined by using a terminal reactivity model. The reactivity ratios were similar to those in conventional radical polymerization as the propagating radicals were identical. Although similar, RAFT and ATRP are not fully interchangeable in gradient polymerization with RAFT offering a simpler approach to gradient polymers when the CTA compatible with both monomers is selected.

更新日期：2023-10-27

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