Kim Miju, Doh Junsang, Lee Daeyeon
Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 790-784, Republic of Korea.
ACS Macro Lett. 2016 Apr 19;5(4):487-492. doi: 10.1021/acsmacrolett.6b00124. Epub 2016 Mar 30.
Polyelectrolyte microcapsules represent a versatile platform to encapsulate and release active ingredients. Understanding the effect of environmental conditions on the mechanical properties of microcapsules is critically important for enabling their applications under various settings. In this report, we investigate the effect of solution pH on the mechanical properties of polyelectrolyte microcapsules made of two weak polyelectrolytes (poly(acrylic acid) and branched poly(ethylenimine)), formed via recently introduced nanoscale interfacial complexation in emulsion (NICE). Interestingly, the stiffness of the NICE microcapsule shell is reduced significantly (by 2 orders of magnitude) when the solution pH is raised from 2 to 6 even though there is little change in the size of microcapsules. These seemingly counterintuitive results suggest that the molecular structure of NICE microcapsules may be different from those of conventional polyelectrolyte microcapsules. The possibility of tuning the shell stiffness without inducing significant changes in the microcapsule size could offer unique advantages in practical applications.
聚电解质微胶囊是一种用于封装和释放活性成分的多功能平台。了解环境条件对微胶囊机械性能的影响对于使其在各种环境下的应用至关重要。在本报告中，我们研究了溶液pH值对由两种弱聚电解质（聚丙烯酸和支化聚乙烯亚胺）制成的聚电解质微胶囊机械性能的影响，这些微胶囊是通过最近引入的乳液中的纳米级界面络合（NICE）形成的。有趣的是，当溶液pH值从2提高到6时，尽管微胶囊的尺寸几乎没有变化，但NICE微胶囊壳的硬度却显著降低（降低了2个数量级）。这些看似违反直觉的结果表明，NICE微胶囊的分子结构可能与传统聚电解质微胶囊不同。在不引起微胶囊尺寸显著变化的情况下调节壳硬度的可能性在实际应用中可能具有独特的优势。
