Ye Congwang, Pajo Bianka, Martinez Carlos J
Materials Engineering Division, Lawrence Livermore National Lab, Livermore, CA 94550, USA.
School of Materials Engineering, Purdue University, 701 West Stadium Ave, West Lafayette, IN 47907, USA.
Soft Matter. 2025 Jan 15;21(3):504-513. doi: 10.1039/d4sm01107d.
Within coating formulations, microcapsules serve as vehicles for delivering compounds like catalysts and self-healing agents. Designing microcapsules with precise mechanical characteristics is crucial to ensure their contents' timely release and minimize residual shell fragments, thereby avoiding adverse impacts on the coating quality. With these constraints in mind, we explored the use of 1 cSt PDMS oil as a diluent (porogen) in trimethylolpropane trimethacrylate (TMPTMA)-based to fabricate microcapsules with customized mechanical properties and submicrometer debris size after shell breakup that can encapsulate a wide range of compounds. Microcapsules were fabricated from double emulsion templates featuring an aqueous core and shells with different PDMS : TMPTMA volume percent ratios. Their mechanical properties under compression and their capacity for encapsulation were characterized. PDMS : TMPTMA ratios exceeding 20 : 80 caused phase separation during crosslinking, leading to a porous shell structure of TMPTMA clusters. The strength of the microcapsules decreased as the PDMS:TMPTMA ratio increased, with ratios above 30 : 70 resulting in mechanically fragile microcapsules fracturing into fragments <10 μm in size. Microcapsules produced with a 0 : 100 PDMS : TMPTMA ratio exhibited strong mechanical properties and were capable of encapsulating small volatile compounds like 1,4-diazabicyclo[2.2.2]octane (a catalyst), while those with ratios >30 : 70 were only suitable to encapsulate larger molecules. The combination of PDMS:TMPTMA chemistry and the precise control provided by the double emulsion generation process in microcapillary devices makes PDMS:TMPTMA a versatile system suitable for various pressure-sensitive encapsulation applications.
在涂料配方中，微胶囊用作输送催化剂和自修复剂等化合物的载体。设计具有精确机械特性的微胶囊对于确保其内容物的及时释放并将残留的壳碎片降至最低至关重要，从而避免对涂层质量产生不利影响。考虑到这些限制因素，我们探索了使用1厘沲的聚二甲基硅氧烷（PDMS）油作为稀释剂（致孔剂），在基于三羟甲基丙烷三甲基丙烯酸酯（TMPTMA）的体系中制备具有定制机械性能且壳破裂后碎片尺寸为亚微米级的微胶囊，这种微胶囊能够封装多种化合物。微胶囊由具有水相核心和不同PDMS:TMPTMA体积百分比比的壳的双重乳液模板制成。对它们在压缩下的机械性能及其封装能力进行了表征。PDMS:TMPTMA比例超过20:80会在交联过程中导致相分离，从而形成TMPTMA簇的多孔壳结构。随着PDMS:TMPTMA比例的增加，微胶囊的强度降低，比例高于30:70会导致机械脆弱的微胶囊破碎成尺寸小于10μm的碎片。以0:100的PDMS:TMPTMA比例制备的微胶囊表现出很强的机械性能，能够封装1,4 - 二氮杂双环[2.2.2]辛烷（一种催化剂）等小挥发性化合物，而比例大于30:70的微胶囊仅适合封装较大分子。PDMS:TMPTMA化学组成与微毛细管装置中双重乳液生成过程所提供的精确控制相结合，使得PDMS:TMPTMA成为适用于各种压敏封装应用的通用体系。
