The utility of pentafluorophenyl esters for the selective introduction of functional units and branch points in well-defined poly(acrylic acid) (PAA) derivatives is demonstrated using a combination of controlled radical polymerization and postpolymerization modification. Reversible addition-fragmentation chain transfer enables the synthesis of well-defined copolymers-poly(pentafluorophenyl acrylate-co-tert-butyl acrylate)-with the active ester repeat units serving as attachment points for reaction with primary amines, specifically tris(2-(t-butoxycarbonyl)ethyl)methyl amine (Behera's amine). Deprotection using trifluoroacetic acid removes both the backbone and side chaint-butyl esters to give a series of branched PAA derivatives containing novel tricarboxylic acid side chains that are well suited to complexation and multidentate interactions. Surprisingly, the active ester homopolymer is shown to have the highest reactivity with Behera's amine when compared to copolymers with lower incorporation of pentafluorophenyl esters, suggesting an intriguing interplay of neighboring group effects and steric interactions. The ability to tune the efficiency of postpolymerization modification gives a library of PAA derivatives.

中文翻译：

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通过聚合后改性有效合成支化聚（丙烯酸）衍生物

使用受控自由基聚合和聚合后改性的组合证明了五氟苯基酯在明确定义的聚（丙烯酸）（PAA）衍生物中选择性引入功能单元和分支点的效用。可逆的加成-断裂链转移能够合成定义明确的共聚物 - 聚（丙烯酸五氟苯基丙烯酸酯 - 共聚丙烯酸叔丁酯） - 具有活性酯重复单元作为与伯胺反应的连接点，特别是三（2-（叔丁氧羰基）乙基）甲胺（Behera's 胺）。使用三氟乙酸去保护同时去除主链和侧链叔丁酯，得到一系列支链 PAA 衍生物，其中包含非常适合络合和多齿相互作用的新型三羧酸侧链。令人惊讶的是，与五氟苯基酯掺入量较低的共聚物相比，活性酯均聚物与 Behera 胺的反应性最高，这表明相邻基团效应和空间相互作用之间存在有趣的相互作用。调整聚合后改性效率的能力提供了一个 PAA 衍生物库。