In recent years, monodisperse functional polymer particles have attracted intensive attention due to their promising prospects in numerous application fields. Herein, monodisperse polymaleimide (PMI) microspheres with excellent thermal stability and a high glass transition temperature were facilely prepared by self-stabilized precipitation polymerization (2SP) of maleimide. The effects of the reaction medium, monomer and initiator concentrations, reaction temperature, and cross-linker dosage on the size and morphology of the as-prepared PMI microspheres were systematically investigated. By simply adjusting the monomer and initiator concentration and reaction temperature, monodisperse spherical PMI microspheres were successfully obtained in high yield (close to 100%) in ethyl acetate with tunable diameters of 0.24–1.08 μm. To elucidate the nucleation, stabilization, and growth mechanism, the size, surface morphology, and molecular weight of the as-prepared PMI microspheres were monitored over the polymerization process. As expected, the particle growth was mainly attributed to the continuous deposition of newly formed PMI chains onto the surface of the PMI nuclei, which is in good agreement with the traditional 2SP process. Furthermore, the intermolecular hydrogen-bonding interactions between imide and carbonyl groups might also exert an important influence on the stabilization and growth of the PMI particles, which were verified by the 2SP polymerization of MI in the presence of urea and succinimide.

中文翻译：

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自稳定沉淀聚合法简便高产地合成单分散耐热聚马来酰亚胺微球

近年来，单分散功能聚合物颗粒因其在众多应用领域的广阔前景而受到广泛关注。在此，通过马来酰亚胺的自稳定沉淀聚合（2SP）轻松制备了具有优异热稳定性和高玻璃化转变温度的单分散聚马来酰亚胺（PMI）微球。系统研究了反应介质、单体和引发剂浓度、反应温度和交联剂用量对所制备的 PMI 微球的尺寸和形貌的影响。通过简单地调节单体和引发剂浓度以及反应温度，在乙酸乙酯中以高收率（接近100%）成功获得单分散球形PMI微球，其直径可调至0.24-1.08μm。为了阐明成核、稳定和生长机制，在聚合过程中监测了所制备的 PMI 微球的尺寸、表面形态和分子量。正如预期的那样，颗粒的生长主要归因于新形成的 PMI 链连续沉积到 PMI 核表面，这与传统的 2SP 过程非常一致。此外，酰亚胺和羰基之间的分子间氢键相互作用也可能对PMI颗粒的稳定和生长产生重要影响，这一点通过MI在尿素和琥珀酰亚胺存在下的2SP聚合得到证实。