The demand to control the molecular weight distribution (MWD) of polymers has gained an unprecedented upsurge for its great importance in enhancing polymer properties. This motivates the development of efficient synthetic methods aiming to predicatively and precisely tailor the MWD. In this work, 2-bromomaleimide (MBr) was used as a monomeric retarder to hinder the chain growth in the reversible addition–fragmentation chain transfer (RAFT) polymerization of methyl methacrylate (MMA), resulting in the broadening of the MWD of PMMA with a high dispersity (Đ). Đ could be well tuned between 1.2 and 2.0 by changing the feed ratio of the initial concentration of MBr to the chain transfer agent (CTA). To further control the MW and Đ, furan-protected MBr (FMBr), referred to as a latent monomeric retarder, was used to manipulate the release of MBr via a retro-Diels–Alder reaction at an elevated temperature. As FMBr remained intact at a low temperature (40 °C) while it underwent deprotection at a high temperature (110 °C), the onset of MBr release could be well controlled by temperature programming to fine-tune the MWD. The concept of a latent monomeric retarder introduced a simple and non-invasive way to finely adjust the MW and Đ, advancing the methodology research on MWD control.

中文翻译：

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通过潜在的单体缓凝剂精细控制分子量和聚合物分散性

控制聚合物的分子量分布（MWD）的需求因其对提高聚合物性能的重要性而获得了空前的热潮。这激发了有效合成方法的发展，旨在预测和精确地定制MWD。在这项工作中，使用2-溴马来酰亚胺（MBr）作为单体阻聚剂，以阻止甲基丙烯酸甲酯（MMA）的可逆加成-断裂链转移（RAFT）聚合中的链增长，从而导致PMMA的MWD加高分散度（Đ）。Đ可以在1.2和2.0之间，通过改变MBR的初始浓度的进料比，以链转移剂（CTA）以及调谐。为了进一步控制MW和Đ呋喃保护的MBr（FMBr），称为潜在单体阻滞剂，用于在高温下通过逆Diels-Alder反应控制MBr的释放。由于FMBr在低温（40°C）下仍保持完好无损，而在高温（110°C）下进行脱保护时，可以通过温度编程微调MWD来很好地控制MBr释放的开始。潜在的单体缓凝剂的概念引入了一种简单且无创的方法来微调分子量和Đ，从而推动了随钻测井控制的方法学研究。