In this research, two types of lignin-based macroinitiators were prepared using α-bromoisobutyrylation reaction. Hydroxyl groups (OH) of lignin were completely or partially α-bromoisobutyrylated to produce two types of macroinitiators. Lignin-g-polyacrylamide graft copolymers soluble in water over the full range of pH were synthesized by atom transfer radical polymerization (ATRP) of acrylamide initiated from bio-based lignin macroinitiator. Progress of all reactions and synthesis of multiarm star-shaped graft copolymers were evaluated with the help of Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (1HNMR). Depending on the macroinitiator type and reaction condition, the semi-empirical molecular weights of the synthesized copolymers were estimated to be between 19,705 and 52,412 g/mol, and the molecular weights of the arms were in the range of 4919–7821 g/mol. Thermal behavior of the samples was also investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

中文翻译：

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生物基木质素大分子引发剂引发丙烯酰胺原子转移自由基聚合合成多臂星形水溶性接枝共聚物及表征

在这项研究中，使用 α-溴异丁酰化反应制备了两种基于木质素的大分子引发剂。木质素的羟基 (OH) 被完全或部分 α-溴异丁酰化以产生两种类型的大分子引发剂。通过以生物基木质素大分子引发剂引发的丙烯酰胺的原子转移自由基聚合 (ATRP)，合成了在整个 pH 范围内可溶于水的木质素-g-聚丙烯酰胺接枝共聚物。借助傅里叶变换红外光谱 (FTIR) 和质子核磁共振光谱 (1HNMR)，评估了多臂星形接枝共聚物的所有反应和合成的进展。根据大分子引发剂类型和反应条件，合成共聚物的半经验分子量估计在 19,705 和 52,412 g/mol 之间，臂的分子量在 4919–7821 g/mol 范围内。还使用热重分析 (TGA) 和差示扫描量热法 (DSC) 研究了样品的热行为。