Poly(ethylene succinate) (PES) with high chain regularity was synthesized by adding oxalic acid in the melt poly-condensation system. The molar ratios of diethylene glycol succinate (DEGS) units in the polymer chains were diminished from 3.8% to 0.6% when 17 mol% oxalic acid was added. Oxalic acid underwent esterification with ethylene glycol and decarboxylation, producing ethylene glycol monoformate and formate end-capped PES oligomers. The formate endcapping supressed the etherification side reactions. Ethylene glycol formate with a lower boiling point was more easily released by-production than ethylene glycol during the transesterification stage, resulting in a faster transesterification rate. Meanwhile, the molecular weights significantly increased. The high chain regularity endowed the PES with higher melting temperatures of 105 °C and remarkably increased crystallization rates. The mechanical properties, including tensile strength at break, were simultaneously improved for a high-molecular-weight PES sample (M_w = 100 kg/mol).

通过在熔融缩聚体系中加入草酸，合成了具有高链规则性的聚（丁二酸乙二醇酯）（PES）。当添加 17 mol% 的草酸时，聚合物链中二甘醇琥珀酸酯 (DEGS) 单元的摩尔比从 3.8% 减少到 0.6%。草酸与乙二醇进行酯化和脱羧，生成乙二醇单甲酸酯和甲酸酯封端的 PES 低聚物。甲酸酯封端抑制醚化副反应。在酯交换阶段，沸点较低的乙二醇甲酸酯比乙二醇更容易副产，因此酯交换速率更快。同时，分子量显着增加。高链规则性赋予 PES 更高的 105 °C 熔化温度和显着提高的结晶速率。高分子量 PES 样品的机械性能（包括断裂拉伸强度）同时得到改善（Mw ₌  100 千克/摩尔）。