丁二烯是乙烯生产的主要副产物，也是石油化工的重要化学品。因其独特的共轭二烯烃结构，被广泛用于合成橡胶及胶乳制品生产。随着全球及亚太地区乙烯产能的迅速增长，丁二烯产能激增并面临产能过剩危机，亟需开发新型丁二烯基制品。将丁二烯转化为价格低廉、高附加值的丁二烯-马来酸酐共聚物是一个良好的选择。然而，共轭二烯烃与马来酸酐的自由基聚合存在难以控制的交联反应与强烈的Diels-Alder（DA）副反应，它们限制了科学研究与工业生产，因此阐明聚合反应的交联机理及抑制DA副反应实现共聚物的高效制备有着重要意义。本论文系统探究了丁二烯与马来酸酐的DA反应与共聚合过程，阐明了聚合反应的交联机理，并提出了以沉淀聚合法制备线性共聚物和以两步法抑制DA反应从而高效制备交联共聚物微球的策略。最后，以反向硫化法将体系的DA副产物与硫磺（S8）共聚制备极性含硫聚合物并探究了共聚机理，拓宽了DA副产物的潜在应用。主要研究内容与创新成果如下：1. 阐明了丁二烯与马来酸酐自由基共聚合的交联机理，并开发了沉淀聚合制备线性共聚物的方法。结果表明：交联反应的关键因素为高共聚物浓度（≥ 500 mg/mL）与1,2-单元侧乙烯基的官能度（> 2%）。通过降低1,2-单元侧乙烯基官能度或控制引发剂浓度，能够实现沉淀聚合制备线性共聚物。2. 阐明了共轭二烯烃-马来酸酐DA反应动力学及影响因素。结果表明：供电子取代基会强化DA反应活性，无取代基的丁二烯具有较慢的反应速率，控制反应物浓度、温度以及弱供电能力的溶剂，能够降低DA反应速率。3. 探究了丁二烯-马来酸酐DA反应与共聚合反应的竞争过程，开发了两步法实现共聚物的高效制备。结果表明：诱导期的DA反应是限制共聚物产率关键因素。通过预热引发剂溶液以消耗阻聚成分的两步法方案，能够将共聚物产率提升至85%。基于自稳定沉淀聚合实现粒径可控（175 nm ~ 800 nm）交联微球的高效制备，微球呈现出400 nm ~ 620 nm的激发依赖性荧光。4. 开发了DA副产物与硫磺的共聚合方案并提出了聚合机理。结果表明：DA副产物能够在高温下与硫磺共聚并得到2400 g/mol ~ 4000 g/mol的低分子量极性含硫聚合物（DA-S），DA-S共聚物能够形成均匀的水分散液。DA-S共聚合过程包含自由基加成反应、夺氢反应及硫酯化反应。

Butadiene is mainly obtained as a byproduct of ethylene production via steam cracking, and is also an important raw material for petrochemicals. Due to its conjugated diolefin structure (CH2=CH-CH=CH2), butadiene has been used primarily in the industrial production of synthetic rubber and latex products. Along with the expansion of ethylene production in the Asia-Pacific region, the global production capacity of butadiene has increased rapidly and butadiene will face a crisis of overcapacity. It is desirable to develop new butadiene-based materials. Converting butadiene into cost-effective and high-value butadiene-maleic anhydride (MAH) copolymer is a good choice. However, the radical polymerization of conjugated diolefins and MAH presents major challenges. Uncontrollable cross-linking reaction and strong Diels-Alder (DA) side reaction have limited further research and industrial production of the above copolymer. Therefore, it is significant to clarify the cross-linking mechanism of butadiene-MAH copolymerization and inhibit the Diels-Alder side reaction to achieve efficient preparation of butadiene-MAH copolymer.In this dissertation, butadiene is used as a template compound for conjugated diolefins. The Diels-Alder reaction and the copolymerization of butadiene and MAH were investigated, to study the polymerization mechanism and the precipitation polymerization of linear/cross-linked products. The copolymerization of the DA byproduct with sulfur was also investigated. The main research contents and innovative results are as follows:1. The cross-linking mechanism of butadiene-MAH copolymerization was investigated, and methods for preparing linear copolymers by precipitation polymerization were developed. The results showed that the critical factors of cross-linking reaction were the high copolymerization (≥ 500 mg/mL) and functionalities of 1,2-unit side-vinyl (> 2%). With decreasing the functionality of the 1,2-unit side-vinyl or controlling the initiator concentration to suppress cross-linking reaction, two methods of preparing linear copolymers via precipitation polymerization were developed.2. The kinetics and factors of the conjugated diolefins-MAH Diels-Alder reaction were investigated. The results showed that the electron-donating group could enhance the Diels-Alder reaction activity, and unsubstituted butadiene has a lower Diels-Alder reaction rate than isoprene and 1,3-pentadiene. Reducing the reactant concentration and reaction temperature, and choosing a solvent with a weak donor capacity could reduce the rate of Diels-Alder reaction.3. The competing process of Diels-Alder reaction and copolymerization of butadiene and MAH was investigated, and the method for efficient preparation of butadiene-MAH copolymers was developed. The results showed that the Diels-Alder reaction during the induction period is the key factor of limiting copolymer yields. A two-step method of preheating the initiator solution to consume radical inhibitors was developed, increasing the copolymer yield up to 85%. With the self-stabilized precipitation polymerization, copolymer microspheres with various particle sizes (175 nm ~ 800 nm) and high gel fractions (> 90%) were controllably prepared, and exhibited the excitation-dependent fluorescence from 400 nm to 620 nm.4. The copolymerization method of DA byproduct and sulfur (DA-S) was developed, and its mechanism was investigated. The results showed that DA byproduct and MAH could undergo copolymerization at high temperature (160 ℃ ~ 200 ℃) to obtain polar copolymers with low molecular weight (2400 g/mol ~ 4000 g/mol), and DA-S copolymers were able to form a homogeneous aqueous dispersion. The DA-S copolymerization process involved radical addition reaction, H-abstraction reaction, and acylation of thiols with anhydrides.