Bhutkar Siddhant Pravin, Millard Pierre-Eric, Urch Henning, Preece Jon A, Zhang Zhibing
School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, U.K.
BASF SE, 67056 Ludwigshafen am Rhein, Germany.
ACS Appl Mater Interfaces. 2025 May 28;17(21):31522-31533. doi: 10.1021/acsami.5c06238. Epub 2025 May 14.
Microencapsulation technology can be used for safe handling and controlled release of agrochemicals. Commercial microencapsulated formulations typically use cross-linked polymeric microcapsules, which encapsulate agrochemicals for improved efficiency and precise application. However, these polymeric microcapsules are nonbiodegradable and add to the growing microplastic pollution challenge at the end of their life cycle. Herein, we demonstrate a simple one-pot process for the interfacial self-assembly of aromatic bis-urea molecules to synthesize microplastic-free microcapsules encapsulating cinmethylin, an effective cineolic pre-emergence herbicide commonly used against grass weeds in annual crops. The urea linkages act as hydrogen-bonding motifs forming a self-assembled supramolecular shell at the oil-water interface. The shell material's chemical composition was analyzed using infrared spectroscopy, H-NMR, and mass spectrometry. Four batches of well-dispersed microcapsules (diameter, 1-10 μm) with encapsulation efficiency >99% and varying payload were synthesized. Accelerated thermal release tests proved that encapsulation reduced the cinmethylin evaporation by up to 90%, over nonencapsulated cinmethylin, and crucially, the release profiles of the bis-urea microcapsules were comparable to conventional polyurea microcapsules prepared industrially. The release rate of cinmethylin increased with payload, indicating that barrier properties of bis-urea microcapsules are tunable, making them adaptable for encapsulating a variety active ingredients. Additionally, all the four batches of bis-urea microcapsules were mechanically stronger than the polyurea microcapsules. Synthesized using a straightforward process requiring no modifications to existing industrial equipment, these bis-urea microcapsules have great potential to replace commercial nonbiodegradable microplastic microcapsules.
微胶囊技术可用于农药的安全处理和控释。商业微胶囊制剂通常使用交联聚合物微胶囊，其将农药封装起来以提高效率和精准施用。然而，这些聚合物微胶囊不可生物降解，在其生命周期结束时加剧了日益严峻的微塑料污染挑战。在此，我们展示了一种简单的一锅法，用于芳香族双脲分子的界面自组装，以合成不含微塑料的微胶囊，其封装了二甲戊灵，一种常用于一年生作物中防除禾本科杂草的有效二萜类芽前除草剂。脲键作为氢键基序，在油水界面形成自组装超分子壳层。使用红外光谱、氢核磁共振和质谱分析了壳材料的化学成分。合成了四批分散良好的微胶囊（直径为1 - 10μm），包封率>99%且载药量不同。加速热释放试验证明，与未封装的二甲戊灵相比，封装使二甲戊灵的蒸发减少了高达90%，至关重要的是，双脲微胶囊的释放曲线与工业制备的传统聚脲微胶囊相当。二甲戊灵的释放速率随载药量增加，表明双脲微胶囊的阻隔性能是可调的，使其适用于封装多种活性成分。此外，所有四批双脲微胶囊在机械性能上都比聚脲微胶囊更强。这些双脲微胶囊采用无需对现有工业设备进行改造的直接工艺合成，具有取代商业不可生物降解微塑料微胶囊的巨大潜力。
