Anisotropic polymer microspheres (e.g. snowman-like shape) have different properties from isotropic microspheres and they are widely used in photonic crystals, bioengineering, rheology, and so on. These anisotropic polymer microspheres are usually prepared by seed emulsion polymerization, dynamic swelling, microfluidic methods, etc. However, these methods are multi-step and time cost and they are mainly used to prepare neutral polymer microspheres. Dispersion polymerization is a simple method to prepare polymer microspheres, whereas the conventional dispersion polymerization can only produce spherical polymer microspheres due to limitations of nucleation growth mechanism and minimum surface energy theory. In this paper, we report a one-step microwave-assisted dispersion polymerization method that can prepare anisotropic poly(ionic liquid) microspheres with controlled snowman-like morphology. This method is simple and only involves one-step polymerization reaction of a solution containing ionic liquid monomer, cross-linking agent, initiator and stabilizer in anhydrous ethanol at a specific temperature under microwave irradiation for 90 min. The morphology of poly(ionic liquid) microspheres formed at different reaction stages is traced by optical microscopy and scanning electron microscopy. It shows that the rapid formation of cross-linked poly(ionic liquid) microspheres with divinylbenzene as cross-linking agent under microwave irradiation is the key to the formation of anisotropic snowman-like poly(ionic liquid) microspheres. Through varying the amount of monomer, cross-linking agent, initiator, solvent and reaction temperature, the morphology of anisotropic snowman-like poly(ionic liquid) microspheres can be modulated. In addition, using discontinuous microwave irradiation can promote the phase separation and increase the anisotropic level of snowman-like poly(ionic liquid) microspheres.

中文翻译：

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微波辅助分散聚合一步法制备各向异性雪人状聚（离子液体）微球


各向异性聚合物微球（如雪人状）与各向同性微球具有不同的性质，它们广泛用于光子晶体、生物工程、流变学等领域。这些各向异性聚合物微球通常通过种子乳液聚合、动态溶胀、微流控方法等制备。然而，这些方法是多步骤和时间成本的，并且它们主要用于制备中性聚合物微球。分散聚合是制备聚合物微球的一种简单方法，而传统的分散聚合由于成核生长机制和最小表面能理论的限制，只能产生球形聚合物微球。在本文中，我们报道了一种一步微波辅助分散聚合方法，该方法可以制备具有受控雪人状形态的各向异性聚（离子液体）微球。该方法简单，仅涉及将含有离子液体单体、交联剂、引发剂和稳定剂的溶液在无水乙醇中，在特定温度下在微波照射下进行 90 分钟的一步聚合反应。通过光学显微镜和扫描电子显微镜追踪在不同反应阶段形成的聚（离子液体）微球的形态。结果表明，在微波照射下，以二乙烯基苯为交联剂的快速形成交联的聚离子液体微球是形成各向异性雪人状聚离子液体微球的关键。通过改变单体、交联剂、引发剂、溶剂和反应温度的量，可以调节各向异性雪人状聚（离子液体）微球的形态。 此外，使用非连续微波辐照可以促进雪人状聚（离子液体）微球的相分离并提高各向异性水平。