Naderi Mehdi, Farajzadehahary Kiarash, Melchin Timo, Weitzel Hans-Peter, Leiza Jose R, Asua José M
POLYMAT and Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country UPV/EHU, Joxe Mari Korta Center, Avenida Tolosa 72, 20018 Donostia-San Sebastián, Spain.
Wacker Chemie AG, Johannes-Hess-Str. 24, 84489 Burghausen, Germany.
ACS Appl Mater Interfaces. 2025 Jul 30;17(30):43750-43760. doi: 10.1021/acsami.5c12131. Epub 2025 Jul 16.
Emulsion polymers are widely present in numerous applications such as adhesives, coatings, paints, and cementitious materials. In applications such as construction, they are favored in dry form that can be restabilized in the final formulation in the presence of water. This offers advantages in terms of storage, transportation, and final application. This work investigates a pH-switchable stabilizer. Turning off the stabilizer leads to latex particle coagulation and dry polymer isolation. Then, turning it back on recovers the restabilized particles in the form of an emulsion. The success of this process relies on the switchability of the colloidal stabilization system and the surface protection of low glass transition temperature ( < 20 °C) particles through a hard shell, ensuring particle integrity during coagulation and polymer isolation. Carboxyl-containing alkali-soluble resins are identified as promising candidates capable of providing both requirements simultaneously. Low (14 °C) polymer particles of vinyl acetate and vinyl neodecanoate (VeoVa10) stabilized by high alkali-soluble resins were synthesized in seeded semicontinuous emulsion polymerization. The polymer isolation was performed through a sequence of steps, including latex coagulation at pH ≤ 3, water filtration (resulting in approximately 70% water removal), drying, grinding, and reinforcement with kaolin as an anticaking agent. The isolated polymer product was then successfully restabilized in the presence of water by applying energy and increasing the pH.
乳液聚合物广泛存在于众多应用中，如粘合剂、涂料、油漆和胶凝材料。在建筑等应用中，它们以干燥形式受到青睐，在有水存在的情况下，可在最终配方中重新稳定化。这在储存、运输和最终应用方面具有优势。这项工作研究了一种pH可切换稳定剂。关闭稳定剂会导致乳胶颗粒凝聚和干燥聚合物分离。然后，重新开启它会以乳液形式恢复重新稳定化的颗粒。这个过程的成功依赖于胶体稳定系统的可切换性以及通过硬壳对低玻璃化转变温度（<20°C）颗粒的表面保护，确保在凝聚和聚合物分离过程中颗粒的完整性。含羧基的碱溶性树脂被认为是能够同时满足这两个要求的有前景的候选物。在种子半连续乳液聚合中合成了由高碱溶性树脂稳定的醋酸乙烯酯和新癸酸乙烯酯（VeoVa10）的低（14°C）聚合物颗粒。聚合物分离通过一系列步骤进行，包括在pH≤3时乳胶凝聚、水过滤（导致约70%的水去除）、干燥、研磨以及用高岭土作为抗结块剂进行增强。然后，通过施加能量和提高pH值，成功地在有水存在的情况下使分离出的聚合物产品重新稳定化。
