Stability of poly(N‐propargylamide)s under ultraviolet irradiation

Abstract

This article investigates the photostability of poly(N-propargylamide)s under different conditions, on the basis of which application research for this class of highly functional polymers can be performed. With helical polymer 1 [monomer: CBCCH 2 NHCOCH(C 2 H 5 ) 2 ] taken as a representative, some affecting factors, including the ultraviolet (UV)-light intensity, presence of oxygen, far-UV and near-UV light, and temperature, were investigated. It was found that increasing the UV-light intensity accelerated the degradation of polymer 1. When oxygen was present, it also facilitated the degradation. Far-UV light rather than near-UV light played a predominant role in initiating the degradation of polymer main chains. Elevating the temperature of the polymer solution during UV irradiation made the degradation accelerate. Storing the polymer under weak UV light, in the absence of oxygen, and at a low temperature was favorable for keeping the polymer stable. These findings are important not only from a scientific point of view but especially for developing practical applications of this type of polymer on the basis of its photodegradability.

Medium‐Entropy Monosilicates Deliver High Corrosion Resistance to Calcium‐Magnesium Aluminosilicate Molten Salt

“…Summary of recently reported representative data, along with data from this study, regarding the corrosion depth of EBC/TBC materials when exposed to molten CMAS. [3,[10][11][12][13][14][15][16][17][18][19][20]22,24,25,[38][39][40] blocks. CMAS powders were prepared using the solid-phase method, with a molar ratio of Ca 33 Mg 10 Al 13 Si 44 .…”

“…Summary of recently reported representative data, along with data from this study, regarding the corrosion depth of EBC/TBC materials when exposed to molten CMAS. [ 3,10–20,22,24,25,38–40 ] …”

“…The corrosion layers on these materials measured merely 28.8 μm after 50 h and 35.4 μm after 100 h at 1500 °C. According to available literature, [3,[10][11][12][13][14][15][16][17][18][19][20]22,24,25,[38][39][40] these medium-entropy silicates show the slimmest corrosion thickness among comparable T/EBC materials under similar corrosion conditions, as demonstrated in Figure 9. The specific power output of a gas turbine engine increases proportionally with the inlet temperature.…”

“…[8,9,10] The thickness of corrosion products serves as a measure of a material's resistance to CMAS corrosion, where CMAS does not penetrate the coating material, a thinner corrosion layer signifies reduced material consumption. Rare earth materials like zirconate, [11,12,13] hafnate, [14,15] oxide, [16] and tantalate [17] exhibit superior performance as coating materials compared with traditional TBC materials, yttria-stabilized zirconia (YSZ), at 1300-1350 °C. However, the surface temperature of EBCs may increase to ≥1400 °C.…”

Challenges and Strategies for Synthesizing High Performance Micro and Nanoscale High Entropy Oxide Materials

“…The former primarily involves solid‐phase synthesis, where entropy's contribution is particularly significant, necessitating high sintering temperatures, extended reaction times, ultra‐fast quenching, and cooling processes. [ 14–16 ] In contrast, bottom‐up methods typically involve liquid‐phase synthesis, which can reduce the required energy barriers, as the atomic‐level mixing of multiple elements in the liquid phase provides a certain configuration entropy. [ 17–19 ] However, experimental exploration of synthesis conditions for HEO MNMs is time‐consuming.…”