随着工业生产发展，化石基材料由于其不可再生、不可降解等性质，对生态环境造成了一定的影响，为了解决这一问题，同时也为了保护环境，实现绿色合成，本文基于Bronsted酸性离子液体在聚合反应中的催化性能，将其作为反应介质进行生物基聚酯的合成，以解决在传统聚合反应中存在的金属残留和有机试剂的大量使用等问题。

本文通过详细表征所用离子液体的热稳定性并计算其Hammett酸度，探讨了该类性质对聚合反应的影响。本文中所涉及的磺酸功能化Bronsted酸性离子液体，其两种性质均主要由阴离子来决定。热重分析表明， [BSMIM][BF₄]存在两个分解温度，在约110 ℃时该离子液体的阴离子首先分解。

本文详细研究了1,6-己二醇和1,4-丁二酸的预缩聚和后缩聚过程。在预缩聚的研究中，凝胶渗透色谱法（GPC）表明预缩聚过程的产物分子量增长速率呈降低趋势，反应动力学近似三级反应的动力学模型，产物分子量增长的主要抑制因素为反应物酸浓度的降低。在后缩聚的研究中，基于Bronsted酸性离子液体在聚酯合成中具有优异的催化性能，通过在1,6-己二醇和1,4-丁二酸的后缩聚反应过程中引入Bronsted酸性离子液体，并优化反应条件（如反应温度、除水方式等），发现最佳的反应温度为110 ℃，最有效率的除水方式是在体系中通入持续氮气流，而催化性能最佳的离子液体为[BSMIM][HSO₄]。后缩聚的反应初期符合外加酸催化的二级反应动力学模型，随着反应的进行，聚合物在磺酸功能化Bronsted酸性离子液体[BSMIM][HSO₄]以及[BSMIM][TFS]中分子量变化的现象却完全不同，这可能是由于磺酸功能化Bronsted酸性离子液体的解离平衡不同而致使离子液体的组成不同，从而使得反应路径不同所致。另外，核磁共振氢谱图表明体系中抑制产物分子量增长的副反应主要有两种，分别是醚及烯类衍生物的形成。通过使用去离子水或异丙醇溶解磺酸功能化的Bronsted酸性离子液体即可简单地分离离子液体和产物，并且离子液体可多次重复使用，离子液体的催化性能均无明显变化。

本文将Bronsted酸性离子液体引入聚乙醇酸和ε-己内酯的聚合反应中，并通过对比得知其最适合的反应温度为160 ℃，最佳的除水方式为在体系中通入持续氮气流。在相同条件下，当离子液体的质量等同于反应物的用量时获得的产物分子量最高，而增加或降低离子液体的用量均会降低产物分子量。通过调节单体比例这一简单方式即可获得具有不同比例的结构单元的聚酯，从而调控其结构，使其用途更为广泛。动力学分析表明，ε-己内酯在聚合初期快速开环，随后通过酯交换实现聚合反应，整个反应的动力学接近二级反应动力学模型，符合外加酸催化的反应机理；无规度的计算结果表明，产物在聚合后期趋向无规。另外，利用相分离纯化方式，可使磺酸功能化的Bronsted酸性离子液体在体系中有效分离，3次循环实验后，离子液体的性能稍有下降。

本文实现了在磺酸功能化的Bronsted酸性离子液体中聚酯的合成，聚合反应过程既无需过渡态金属同时也无需额外使用有机试剂，且离子液体的回收性能良好，因此，本文所涉及的聚合反应符合“绿色化学”的要求。

  With the development of industrial production, fossil-based materials have a negative impact on the ecological environment because of their non-renewable and non-degradable properties. Thus, in order to solve this problem, this paper explored the synthesis of bio-based polyesters by using Bronsted acidic ionic liquids as both reaction medium and catalyst based on the excellent performance of Bronsted acidic ionic liquids in polymerization,

   The thermal stability was characterized and Hammett acidity of ionic liquids was calculated in detail, and their effects on polymerization were discussed. For the sulfonic acid functionalized Bronsted acidic ionic liquids studied in this paper, both properties of ionic liquids were mainly affected by the types of anions. [BSMIM][BF₄] has two decomposition temperatures, in which the anion begins to decompose at about 110 ℃.

   With gel permeation chromatography (GPC) monitoring, the molecular weight of the pre-condensation reaction between 1,6-hexanediol and 1,4-succinic acid was monitored and the growth rate of M_w is reduced. The dynamics study shows that the dynamic mechanism of this reaction can be described by the third-order reaction approximately, and the main restriction of the molecular weight growth of the reaction is the decrease of the acid concentration of the reactant. For the post polycondensation process, since Bronsted acidic ionic liquids have excellent catalytic properties in polyester synthesis, we introduced Bronsted acidic ionic liquids into the post-polycondensation of 1,6-hexanediol and 1,4-succinic acid, and fully studied the reaction conditions (reaction temperatures, water removal methods, etc.). The optimum reaction temperature is 110 ℃. For the water removal methods for this reaction, higher molecular weight can be obtained with the dry and continuous nitrogen flow, which means that its water removal efficiency is better. For Bronsted acidic ionic liquids, the types of anions and cations have no obvious effect on the molecular weight of polyesters. The reaction process shows that the initial reaction fits well with the second-order reaction dynamics catalyzed by external acid. With the increasing of the reaction time, the changes of the molecular weight of polymers in sulfonic acid functionalized Bronsted acidic ionic liquids [BSMIM][HSO₄] and [BSMIM][TFS] are completely different, which may be due to the dissociation equilibrium of sulfonic acid functionalized Bronsted acidic ionic liquids, which leads to a completely different reaction route. In addition, through the characterization of ¹H NMR spectra, it can be known that there are two main side reactions in the system that inhibit the molecular weight growth of products, namely, the formation of ethers and alkene derivatives. By using deionized water or isopropanol to dissolve the sulfonic acid functionalized Bronsted acidic ionic liquid, ionic liquids and the product can be easily separated, and the ionic liquids can be reused for many times with no obvious change of the molecular weight.

    The polymerization of poly(glycolic acid) and ε-caprolactone in Bronsted acidic ionic liquid was studied. The most suitable reaction temperature is 160 ℃ and the best way to remove water is to blow dry nitrogen, which can contribute to a higher number average molecular weight. For the amount of ionic liquid, under the same conditions, when the mass of ionic liquid is equal to the mass of reactants, the molecular weight of the product is the highest. Increasing or decreasing the amount of ionic liquid will reduce the number average molecular weight of the products. By adjusting the ratio of monomers, the polymers with different ratios of polymerization units can be obtained, and the structure and properties of the polymers can be changed, which contributes to a wider range of the applications of the polymers. With the help of ¹H NMR spectra, the whole reaction process was successfully monitored, and the dynamics were also studied. It can be found that the ring opening of ε-caprolactone can be achieved rapidly in the initial stage of polymerization by the attack of hydrogen ions provided by sulfonic acid functionalized Bronsted acidic ionic liquid, and this process is very fast, which has little effect on the whole reaction dynamics. Then the polymerization is realized by the transesterification process, and the dynamic mechanism of the whole reaction is close to the second-order reaction, which is consistent with the reaction mechanism of external acid catalysis. In addition, the calculations of the degree of randomness show that the products tend to be more like random polymers with the increase of times. Moreover, the sulfonic acid functionalized Bronsted acidic ionic liquid can also be effectively separated in this system through phase separation. However, the catalytic performance of ionic liquid has a slight decline after three cycles.

    Since the synthesis reactions of both polyesters in sulfonic acid functionalized Bronsted acidic ionic liquids need neither transition metal nor additional organic solvents, and the recycled performance is ideal, this kinds of polymerization can be definitely called “green” reaction due to the fulfillment of the requirement of "green chemistry".