沉淀聚合高收率制备单分散聚脲微球及其功能化

Uniform polymer microspheres prepared by precipitation polymerization are free of surfactant or stabilizer, and have been widely applied in diverse fields owing to their neat surface. However, monomer concentration in this process is usually limited to 5%, and monomer conversion is usually below 70% with low microspheres yield and high residual monomer. At the same time, amino-functionalized microsphere prepared by precipitation polymerization is rarely reported in literature, and the sole reported research is either with low monomer content or with complicated and time-consumed process. Here uniform polyurea microspheres with amine groups on the surface will be achieved via a novel one-step precipitation polymerization based on the reaction of water and isophorone diisocyanate in water-acetone mixed solvent. This research is expected to increase monomer content and sphere yield by changing polymerization conditions. Compared with all reported methods, this protocol is very simple. Full monomer conversion can be achieved without any residual monomer. And uniform microspheres can be obtained with the reactor just standing still without any shaking or stirring, which endows the process with low cost and low energy consumption. These will be very helpful for the large scaled production of uniform microspheres. Full characterization of this precipitation polymerization system will be carried out, and the formation and growth mechanism of the microsphere will be summarized. These amine functionalization microspheres will be used for covalent immobilization of enzyme, and studies of their application will be carried out. This research is of great importance in both fundamental science and advanced industries.

沉淀聚合制备聚合物单分散微球无需表面活性剂或稳定剂，所得微球因表面洁净而获得广泛应用。但该方法中单体用量一般不超过5%，微球产率及单体转化率也较低(<70%)。同时使用沉淀聚合制备表面带胺基微球的报道较少，仅有研究中或单体用量低或步骤繁琐，耗时较长。本课题仅使用异佛尔酮二异氰酸酯一种单体，利用其与水的反应在静置不搅拌条件下通过沉淀聚合制备单分散聚脲微球。通过改变聚合条件实现微球高收率。本课题无需进行任何表面改性一步到位即可获得胺基化微球。该方法过程简单，原料单一，单体可完全转化，微球收率高，耗时短，成本低，经济实用，有助于推动单分散微球的规模化生产。完全不同于以往的自由基沉淀聚合，本课题基于逐步聚合机理获得聚合物单分散微球，通过对微球形成与增长机理的探讨，丰富沉淀聚合的理论。此外，将利用微球表面的丰富胺基进行生物酶固定，并对其应用进行研究。本课题既有很好的学术意义，也有重要的应用价值。

聚合物单分散微球在色谱分析和酶固定等领域有重要的应用价值，已成为高分子科学的一个重要研究内容。沉淀聚合制备聚合物单分散微球时不需表面活性剂或稳定剂，所得微球因表面洁净而备受关注。在本课题立项之前沉淀聚合的相关研究都是基于自由基聚合机理，存在着单体用量低(<5.0%)和聚合时间长(12~24 h)等问题，严重制约了聚合物单分散微球的生产及相关应用和发展。本课题以二异氰酸酯化合物为单体，使用丙酮等与水组成的混合溶剂为反应介质，在静置不搅拌条件下通过沉淀聚合高收率制备了单分散聚脲微球，对所得微球进行了表征并总结了微球的形成和增长机理，对微球在酶固定领域的应用进行了探讨。.为实现微球高收率，变化了反应温度、溶剂及单体种类等条件进行实验。结果表明，以异佛尔酮二异氰酸酯(IPDI)为单体时制得了单分散微球，而使用甲苯二异氰酸酯和六亚甲基二异氰酸酯制得了聚脲多孔材料。以水和二甲基甲酰胺(DMF)及水和丙酮为溶剂制备单分散微球时IPDI的装载量最高分别为6.0%和11.0%，而使用水和乙腈为溶剂时IPDI用量最高达到了23.0%，微球产率为95.1%，制备单分散微球的效率显著提高，有利于实现其规模化生产。反应温度及水和单体的用量对聚合反应速率影响显著。聚合过程中初级微球的形成较慢，而微球的增长速度相对较快且在增长过程中微球的数目恒定，未发生聚并。所得聚脲微球具有较高的耐热性且表面富含胺基。由于氢键或交联作用，聚脲微球难溶于大部分的有机溶剂中。首次通过高分辨魔角旋转核磁对聚脲固体进行了表征并获得了高质量的核磁谱图，结果表明本课题所得线性及交联聚脲中都不存在缩二脲结构。使用戊二醛对微球进行改性并以改性微球为载体对漆酶进行了固定化，探讨了最佳的酶固定条件。固定化后漆酶的耐热性、pH稳定性及储存稳定性显著提高。固定酶对雷玛唑亮蓝染料有较好的降解效果和重复使用性，重复利用7次后脱色率仍保持首次的65%。本课题既具有重要的学术价值，也具有重要的应用前景。