Carborane polyimides, synthesis and characterization

Abstract

Here we report the syntheses of polyimides with meta-carborane cages embedded in the polymer chain and their characterizations. Aromatic carborane diamines were prepared by a Sonogashira reaction in the first place; reaction of the obtained diamines with commercially available dianhydride led to the formation of carborane polyimides with high molecular weight. Thermogravimetric analysis (TGA) of the samples showed that they have excellent thermal stability, with 5 wt% decomposition temperatures (T d5% ) higher than 520 C. Due to the boron-rich nature of the obtained polyimides, samples prepared here have potential applications in the aerospace industry and nuclear power stations as building blocks for neutron shielding and detecting devices.

Syntheses of novel soluble carborane polyimides with ultrahigh thermal stability

“…The bulky cages reduce chain‐to‐chain charge transfer interactions and disrupt regular chain packing, while another reason is the electron‐withdrawing property of the cages which reduces inter‐ and intramolecular interaction and results in less dense chain packing. Thus the segments of the chain can move at relatively low temperatures . TGA of these samples was performed in both nitrogen and dry air.…”

HighTgand Thermo‐Oxidatively Stable Thermosetting Polyimides Derived from a Carborane‐Containing Diamine

“…Polymers with carboranes as building blocks, such as polyurethanes, polythiophenyls, polysiloxanes, and polyimides, are getting some attention due to their good solubility, thermal and thermo‐oxidative stability, and high T g . For example, Huang et al.…”

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thermal stability by introducing organic heterocyclic groups into polymers' chains. [7,[16][17][18] Polymers with carboranes as building blocks, such as polyurethanes, [19] polythiophenyls, [20] polysiloxanes, [21,22] and polyimides, [23][24][25] are getting some attention due to their good solubility, thermal and thermo-oxidative stability, and high T g . For example, Huang et al reported that an m-carborane-containing polybenzoxazine had outstanding thermooxidative stability and high T g .

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A new way for lead–boron resin composite modification: SiO2 coated lead powders by a sol–gel method

“…Nuclear shielding composites are important materials used for blocking g rays and neutron radiation to ensure safety of personnel and machines. [1][2][3][4][5] Lead-boron polyethylene (PBPE) is widely used for nuclear shielding. The resins have good moderating effect on fast neutrons, while boron atoms can absorb thermal neutrons effectively and Pb atoms have effective shielding effect on g rays.…”