Substantial Confinement of Crystal Growth of Organic Crystalline Materials in Metal-Organic Membrane Microshells.

This study proposes a robust microshell encapsulation system in which a metal-organic membrane (MOM), consisting of phytic acids (PAs) and metal ions, intrinsically prevents the molecular crystal growth of organic crystalline materials (OCMs). To develop this system, OCM-containing oil-in-water (O/W) Pickering emulsions were enveloped with the MOM, in which anionic pulp cellulose nanofiber (PCNF) primers electrostatically captured zinc ions at the O/W interface and chelated with PA, thus producing the MOM with a controlled shell thickness at the micron scale. We ascertained that the MOM formation fills and covers ∼75% of the surface pore size of PCNF films, which enhances the interfacial modulus by 2 orders of magnitude compared to that when treated with bare PCNFs. Through a feasibility test using a series of common OCMs, including ethylhexyl triazone, avobenzone, and ceramide, we demonstrated the excellent ability of our MOM microshell system to stably encapsulate OCMs while retaining their original molecular structures over time. These findings indicate that our MOM-reinforced microshell technology can be applied as a platform to substantially confine the crystal growth of various types of OCMs.

Shear-Responsive Sol-Gel Transition of Phase Change Material Emulsions for an Injectable Thermal Insulation Platform.

Phase change materials (PCMs) have attracted significant attention as promising insulating materials. However, they often suffer from the simple yet critical problem of leakage in practical applications. Therefore, in this study, an injectable PCM emulsion insulation platform is developed. For this, n-hexadecane, as a PCM, emulsion droplets are armored with a metal-organic membrane (MOM) through the coordination of zinc ions and phytic acid. The MOM layer not only provides a rigid interfacial modulus but also allows the emulsion to exhibit viscoelastic behavior by shear stress-induced interdrop association. This MOM-enveloped PCM emulsion (PCMEMOM ) exhibited typical sol-gel transition behavior in response to applied shear stress, indicating the injectable characteristic of the PCMEMOM . After observing the rheological hysteresis and thermal stability of the PCMEMOM under repetitive heating and cooling cycles, the thermal insulation performance of PCMEMOM is quantitatively and visually demonstrated. These findings suggest an efficient method to exploit high-performance insulation systems.