Polymeric materials based on fatty acids (FAs) have a combination of characteristics (alkene groups, hydrophobicity, tuneable T_g) that give them great potential as renewable, high value materials. Here, we investigate the base catalysed transesterification of four different plant oils (high oleic sunflower, olive, hydrogenated coconut and hydrogenated rapeseed) with N-hydroxyethyl acrylamide. By conducting kinetics experiments, investigating potential side reactions and improving isolation of the target products, we were able to identify reactive impurities (radical inhibitors, unintended co-monomers) that were found to remain in the impure brine washed plant oil-based monomers (POBM). Kinetics experiments were then performed to investigate the RAFT polymerisation of these monomers. It was found that the more sustainable brine washing process was viable for the controlled radical polymerisation of the higher k_{p app} (saturated) monomers, however column purification was necessary for good control of unsaturated monomers. Polymers with values of M_n between 3000 and 12 000 g mol⁻¹ were synthesised and dependent on the FA source exhibited either amorphous or semi-crystalline behaviour (T_g values between −1 and 33 °C, T_m values between 48 and 66 °C). This work demonstrates the first example of RAFT polymerisation of acrylamide monomers derived from plant oils by a one step direct transesterification, opening the door for novel well-defined, functional bio-based polymers.

中文翻译：

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源自植物油的疏水性丙烯酰胺单体的合成和 RAFT 聚合


基于脂肪酸 （FA） 的聚合物材料具有多种特性（烯烃基团、疏水性、可调节的 T_g），这使它们成为可再生、高价值材料具有巨大潜力。在这里，我们研究了四种不同植物油（高油酸葵花籽油、橄榄油、氢化椰子油和氢化油菜籽油）与 N-羟乙基丙烯酰胺的碱催化酯交换反应。通过进行动力学实验、研究潜在的副反应和改进目标产物的分离，我们能够识别出发现残留在不纯盐水洗涤植物油基单体 （POBM） 中的反应性杂质（自由基抑制剂、意外的共聚单体）。然后进行动力学实验以研究这些单体的 RAFT 聚合。研究发现，更可持续的盐水洗涤工艺对于较高 k_{p app}（饱和）单体的受控自由基聚合是可行的，但为了很好地控制不饱和单体，色谱柱纯化是必要的。合成了 M_n 值在 3000 和 12 000 g ^mol-1 之间的聚合物，并且依赖于 FA 源表现出无定形或半结晶行为（T_g 值在 -1 和 33 °C 之间，T_m 值在 48 和 66 °C 之间）。这项工作展示了通过一步直接酯交换对植物油衍生的丙烯酰胺单体进行 RAFT 聚合的第一个例子，为新型定义明确的功能性生物基聚合物打开了大门。