The present paper regards the development of polyurea/polyurethane (PUa/PU) and PUa/PU–silica hybrid shell microcapsules (MCs), loaded with Ongronat®2500, a commercial type of oligomeric methylene diphenyl diisocyanate with increased functionality, as core material. Ongronat® 2500 has a wide range of applications either for the production of rigid polyurethane foams and as cross-linking or self-healing agent. The MCs were achieved by a facile, one-pot process, consisting of an oil-in-water microemulsion system combined with interfacial polymerization processing, employing a higher reactivity isocyanate, toluene diisocyanate, to competitively contribute to the shell formation. Ethylenediamine, polyethylenimine (PEI), triethoxy(octyl)silane (n-OTES) and 3-(2-aminoethylamino) propyltrimethoxysilane (aminosilane) were tested as active, or “latent” active hydrogen (H) sources, and their effect on the MCs morphology, encapsulation yield, shelf life, shell’s chemical structure and thermal stability was assessed. The MCs are aimed at the development of a new generation of adhesive formulations, which are mono-component, self-reactive, eco-friendly and with low health hazards, for industries such as the footwear, construction, aerospace and automotive. MCs’ characterization was performed using Fourier transformed infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. It was possible to obtain MCs with a high loading of Ongronat®2500, exhibiting a core–shell morphology, an increased shell resistance to temperature and improved shelf life. The combination of PEI and n-OTES led to the best compromise between encapsulation yield and shelf life. Finally, a confinement effect of the encapsulated macromolecules is herein shown for the first time, by the drastic narrowing of the NCO peak at the FTIR spectrum of the MCs.

中文翻译：

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不同活性氢源在商业低聚二异氰酸酯微胶囊化中的作用

本论文研究了聚脲/聚氨酯 (PUa/PU) 和 PUa/PU-二氧化硅混合壳微胶囊 (MCs) 的开发，装载 Ongronat®2500，一种商业类型的具有增加功能的低聚亚甲基二苯基二异氰酸酯，作为核心材料。Ongronat® 2500 具有广泛的应用，可用于生产硬质聚氨酯泡沫以及作为交联剂或自修复剂。MCs 是通过简单的一锅法实现的，由水包油微乳液系统与界面聚合工艺相结合，采用更高反应性的异氰酸酯，甲苯二异氰酸酯，以竞争性地促进壳的形成。乙二胺、聚乙烯亚胺 (PEI)、三乙氧基(辛基)硅烷 (n-OTES) 和 3-(2-氨基乙基氨基) 丙基三甲氧基硅烷 (氨基硅烷) 经测试具有活性，或“潜在”活性氢 (H) 源，并评估了它们对 MC 形态、封装产率、保质期、壳的化学结构和热稳定性的影响。MC 旨在为鞋类、建筑、航空航天和汽车等行业开发新一代单组分、自反应、环保且对健康危害低的粘合剂配方。MCs 的表征是使用傅立叶变换红外光谱、热重分析和扫描电子显微镜进行的。有可能获得高负载 Ongronat®2500 的 MC，表现出核壳形态，壳对温度的耐受性增加，保质期延长。PEI 和 n-OTES 的组合导致封装产量和保质期之间的最佳折衷。最后，