Instability of emerging perovskite organometallic halide in humidity environment is the biggest obstacle for its potential applications in solar energy harvest and electroluminescent display. Understanding the detailed decay mechanism of these materials in moisture is a critical step towards the final appropriate solutions. As a model study presented in this work, in situ synchrotron radiation x-ray diffraction was combined with microscopy and gravimetric analysis to study the degradation process of CH3NH3PbI3 in moisture, and the results reveal that: 1) intermediate monohydrated CH3NH3PbI3·H2O is detected in the degradation process of CH3NH3PbI3 and the final decomposition products are PbI2 and aqueous CH3NH3I; 2) the aqueous CH3NH3I could hardly further decompose into volatile CH3NH2, HI or I2; 3) the moisture disintegrate CH3NH3PbI3 and then alter the distribution of the decomposition products, which leads to an incompletely-reversible reaction of CH3NH3PbI3 hydrolysis and degrades the photoelectric properties. These findings further elucidate the picture of hydrolysis process of perovskite organometallic halide in humidity environment.

Surface chemical patterns can both cause and direct dewetting in overlying thin polymer films. In this paper we focus on a key factor in this phenomenon, the magnitude of the surface energy difference between surface pattern domains (Dc). To probe the influence of Dc on film dewetting, we utilize novel combinatorial test patterns exhibiting a gradient in Dc. Specifically, our test patterns consist of a series of micron-scale striped regions that continuously change in their surface energy (c) relative to background striped regions having a fixed and calibrated c. Using polystyrene (PS) films as a demonstration case, we employ these test patterns to quantify the morphology and kinetics of dewetting as Dc diminishes. Our study indicates a transition from pattern-directed to isotropic PS dewetting at critical Dc values. For Dc . 14 mJ m 22 , ordered droplet arrays are formed, while for Dc , 7 mJ m 22 , the dewetting is isotropic. A competition between these limiting behaviors is found for a ''crossover regime'', 7 mJ m 22 , Dc , 14 mJ m 22 . These combinatorial test patterns provide a powerful approach for investigating the large number of parameters that govern the stability of ultrathin polymer films, and the physical factors that influence the dewetted film morphology.

Recycling of the thermosetting resin is a big challenge due to the formation of cross-linked, three-dimensional network structures after curing. In this study, a simple mild and effective method was used to synthesize an aromatic amine curing agent containing dynamic disulfide bonds and carbon−nitrogen bonds, which is used to cure epoxy resin (E51) to obtain a degradable thermosetting material with good heat resistance and mechanical properties. The synthesized amine curing agent was characterized by FTIR and 1 H NMR, and the thermodynamic properties, degradability, and remoldability of thermosetting materials were systematically studied. The results show that the heat resistance of the materials was almost unchanged after three repeated cycles of remolding as suggested by constant glass transition and onset degradation temperature. The new curing agent produced the glass fiber reinforced thermosetting composite with a tensile strength and an interlaminar shear strength of 732 and 71 MPa, respectively. In addition, recycling of carbon fiber can be achieved using this new curing agent containing disulfide bonds and dynamic carbon−nitrogen bonds.