In this work, a novel biobased hyperbranched polyester (HBPE) with excellent low-temperature flexibility (low T_g) and thermal stability, was prepared from the self-polycondensation of AB₂ monomer based on methyl ricinoleate (MR), a commercially available derivative from castor oil. The AB₂ monomer was facilely synthesized by UV-initiated thiol-ene addition between MR and 2-mercaptoethanol in the absence of solvents. The reaction parameters were systematically optimized, and the highest yield up to 98 % was achieved with almost complete conversion of double bond within 2 h. A series of HBPEs were then obtained via bulk polymerization of the AB₂ monomer under different conditions. Among the four transesterification catalysts investigated, Ti(OBu)₄ was demonstrated to be the most efficient one due to the higher polymerization efficiency and molecular weight (M_n = 13,000∼17,000 g/mol) of as-obtained HBPEs. And the degree of branching (DB) was estimated to be in the range of 0.30∼0.42. Notably, the HBPEs with dangling chains exhibited a low glass transition temperature (T_g) of ―42.8∼―59.2 °C, indicative of excellent low-temperature flexibility. TGA results indicated that the onset thermal degradation temperature under nitrogen exceeded 310 °C for all the HBPEs. In comparison to the polyrincinoleate as a linear polyester analogue, the HBPE behaved like Newtonian fluid behaviors with lower complex viscosities.

在这项工作中，由AB ₂单体基于蓖麻油酸甲酯（MR）（一种可商购的衍生物）进行自缩聚反应，制备了一种具有优异的低温柔韧性（低T _g）和热稳定性的新型生物基超支化聚酯（HBPE）。从蓖麻油。在不存在溶剂的情况下，通过在MR和2-巯基乙醇之间进行UV引发的硫醇-烯加成反应，轻松合成AB ₂单体。系统优化了反应参数，在2小时内双键几乎完全转化，最高收率达到98％。然后通过AB _2的本体聚合获得了一系列HBPE。单体在不同条件下。在所研究的四种酯交换催化剂中，Ti（OBu）₄被证明是最有效的催化剂，这是因为获得的HBPE的聚合效率更高且分子量更高（M _n = 13,000-17,000 g / mol）。且支化度（DB）估计为0.30〜0.42。值得注意的是，带有悬链的HBPE的玻璃化转变温度低（T _g）为―42.8〜―59.2°C，具有优异的低温柔韧性。TGA结果表明，所有HBPE在氮气下的起始热降解温度均超过310°C。与作为线性聚酯类似物的聚蓖麻油酸酯相比，HBPE的行为像牛顿流体一样，具有较低的复数粘度。