Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method...Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method,we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor.Raman spectrum measurements detected the emerging vibrational peak at 635 cm-1for the polymerized lithium azide sample,indicating the formation of atomic cubic gauche nitrogen(cg-N)with N–N single bonds.Through systematic investigations,the preparation conditions are optimized to be 180℃with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen.The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors.It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.展开更多
Polymeric nitrogen is a potential high-energy-density material with the advantages of high energy density, easy availability of raw materials, and non-pollution. The design and synthesis of polymeric nitrogen are impo...Polymeric nitrogen is a potential high-energy-density material with the advantages of high energy density, easy availability of raw materials, and non-pollution. The design and synthesis of polymeric nitrogen are important in the research field of energetic materials. The cubic gauche nitrogen was successfully synthesized at high pressure in the diamond anvil cell, which stimulated the theoretical and experimental investigations. To date, several hundred kinds of polymeric nitrogen have been reported. This review introduces the progressive development of polymeric nitrogen with high energy density, the challenges faced by the synthesized polymeric nitrogen under high-pressure,and the importance to improve the stability of polymeric nitrogen at ambient pressure. Furthermore, alternative methods for synthesizing polymeric nitrogen under moderate conditions are also presented. In this field, more efforts are needed to develop strategies for stabilizing more polymeric nitrogen to ambient conditions, especially the stability of free surfaces.展开更多
In chain molecules of 1, 2-PBD, there are two kinds of gauche arrangements, which is the cause of making the spectrum of the secondary carbon in main chain of the polymer split. In such a complex system, the gauche ar...In chain molecules of 1, 2-PBD, there are two kinds of gauche arrangements, which is the cause of making the spectrum of the secondary carbon in main chain of the polymer split. In such a complex system, the gauche arrangements of the secondary carbon and the tertiary carbon occupy an important position. Hence, the contribution of the tertiary carbon to the chemical shifts of the secondary carbon has a decisive effect on the sequence structure distribution. In comparison the contribution of vinyl groups is much less. The γ values are: γ_1=-6.37～-6.41 ppm represents the effect of the tertiary carbon and γ_2=0.0～-1.56 ppm the contribution of vinyl. The mean square errors are 0.364 and 0.166×10^(-2) ppm^2, respectively in the two cases of considering the effect of vinyl and vice versa. In this paper, we discuss the effects of model chain type, chain length and temperature on the bond probability. Meanwhile, it is pointed out that there exist a few cases, which are not in accord with the usual distribution in calculation of bond probability. Moreover, the chain structure of syndiotactic 1, 2-PBD is studied in detail with DEPT pulse technique.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406000)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-052).
文摘Polymeric nitrogen has long been pursued as a high-energy density material but is very challenging to synthesize at ambient pressure conditions especially with light element precursors.Using a developed one pot method,we successfully synthesized the atomic polymeric nitrogen employing lithium azide as a precursor.Raman spectrum measurements detected the emerging vibrational peak at 635 cm-1for the polymerized lithium azide sample,indicating the formation of atomic cubic gauche nitrogen(cg-N)with N–N single bonds.Through systematic investigations,the preparation conditions are optimized to be 180℃with a reaction time of 3 h for obtaining atomic cubic gauche polymeric nitrogen.The one pot method achieves the quantitative synthesis of cg-N at ambient pressure using alkali metal azide as the precursors.It offers a simple way for further scalable synthesis of polymeric atomic nitrogen high energy density materials.
基金supported by the CASHIPS Director’s Fund (Grant No. YZJJ202207-CX)。
文摘Polymeric nitrogen is a potential high-energy-density material with the advantages of high energy density, easy availability of raw materials, and non-pollution. The design and synthesis of polymeric nitrogen are important in the research field of energetic materials. The cubic gauche nitrogen was successfully synthesized at high pressure in the diamond anvil cell, which stimulated the theoretical and experimental investigations. To date, several hundred kinds of polymeric nitrogen have been reported. This review introduces the progressive development of polymeric nitrogen with high energy density, the challenges faced by the synthesized polymeric nitrogen under high-pressure,and the importance to improve the stability of polymeric nitrogen at ambient pressure. Furthermore, alternative methods for synthesizing polymeric nitrogen under moderate conditions are also presented. In this field, more efforts are needed to develop strategies for stabilizing more polymeric nitrogen to ambient conditions, especially the stability of free surfaces.
文摘In chain molecules of 1, 2-PBD, there are two kinds of gauche arrangements, which is the cause of making the spectrum of the secondary carbon in main chain of the polymer split. In such a complex system, the gauche arrangements of the secondary carbon and the tertiary carbon occupy an important position. Hence, the contribution of the tertiary carbon to the chemical shifts of the secondary carbon has a decisive effect on the sequence structure distribution. In comparison the contribution of vinyl groups is much less. The γ values are: γ_1=-6.37～-6.41 ppm represents the effect of the tertiary carbon and γ_2=0.0～-1.56 ppm the contribution of vinyl. The mean square errors are 0.364 and 0.166×10^(-2) ppm^2, respectively in the two cases of considering the effect of vinyl and vice versa. In this paper, we discuss the effects of model chain type, chain length and temperature on the bond probability. Meanwhile, it is pointed out that there exist a few cases, which are not in accord with the usual distribution in calculation of bond probability. Moreover, the chain structure of syndiotactic 1, 2-PBD is studied in detail with DEPT pulse technique.
