A novel polyimide(PI) containing pendent biphenyl ester groups was synthesized from 3,5-diaminobenzoic-4′-biphenyl ester (DABBE)and 3,3′,4,4′-oxydiphthalic dianhydride(ODPA) by a one-step high-temperature polyconde...A novel polyimide(PI) containing pendent biphenyl ester groups was synthesized from 3,5-diaminobenzoic-4′-biphenyl ester (DABBE)and 3,3′,4,4′-oxydiphthalic dianhydride(ODPA) by a one-step high-temperature polycondensation in m-cresol.This PI is a semicrystalline polymer.Lots of short fine fibric crystals with length and diameter about 20、μm and 1、μm respectively disperse randomly in the PI film. The optical textures and the X-ray diffraction patterns of the PI solution and film show that the PI main chains are in the extended conformation and pack parallel to each other, and the pendent biphenyl ester groups occupy the space between the main chain layers,more or less perpendicular to the main chains.At the same time, mechanical and thermally stable properties of the PI film were investigated. The excellent mechanical properties of general polyimide films are reasonably maintained, the polyimide film with pendent groups showes higher tensile strength and modulus and lower T g. TGA study showes a typical two-step weight loss behavior corresponding to the pyrolysis of pendent groups and main chains of the PI,respectively.展开更多
Dynamically crosslinked materials generally lose their self-healing ability and mechanical robustness in aqueous,acidic,and basic environments due to disruption of their dynamic interactions and bonds.Herein,a micelle...Dynamically crosslinked materials generally lose their self-healing ability and mechanical robustness in aqueous,acidic,and basic environments due to disruption of their dynamic interactions and bonds.Herein,a micelle-like structure with a hydrophobic outer layer is used to protect ionic interactions.This structure ensures the self-healing and long-term stability of the ionically crosslinked elastomers in aqueous,acidic,and basic environments.The elastomer possesses a tensile strength of 6.7 MPa and a strain at break of 1400%,which is superior to the existing waterproof selfhealing elastomers.The strain sensors and dielectric actuators based on the elastomer are highly stable and self-healable,even in extremely harsh environments.This design strategy of hydrophobic protection for dynamic interactions is quite general,allowing it to be extended to other self-healing materials.展开更多
文摘A novel polyimide(PI) containing pendent biphenyl ester groups was synthesized from 3,5-diaminobenzoic-4′-biphenyl ester (DABBE)and 3,3′,4,4′-oxydiphthalic dianhydride(ODPA) by a one-step high-temperature polycondensation in m-cresol.This PI is a semicrystalline polymer.Lots of short fine fibric crystals with length and diameter about 20、μm and 1、μm respectively disperse randomly in the PI film. The optical textures and the X-ray diffraction patterns of the PI solution and film show that the PI main chains are in the extended conformation and pack parallel to each other, and the pendent biphenyl ester groups occupy the space between the main chain layers,more or less perpendicular to the main chains.At the same time, mechanical and thermally stable properties of the PI film were investigated. The excellent mechanical properties of general polyimide films are reasonably maintained, the polyimide film with pendent groups showes higher tensile strength and modulus and lower T g. TGA study showes a typical two-step weight loss behavior corresponding to the pyrolysis of pendent groups and main chains of the PI,respectively.
基金supported by the National Natural Science Foundation of China(51873110 and 51673120)State Key Laboratory of Polymer Materials Engineering(sklpme2019-2-14)the Fundamental Research Funds for Central Universities。
文摘Dynamically crosslinked materials generally lose their self-healing ability and mechanical robustness in aqueous,acidic,and basic environments due to disruption of their dynamic interactions and bonds.Herein,a micelle-like structure with a hydrophobic outer layer is used to protect ionic interactions.This structure ensures the self-healing and long-term stability of the ionically crosslinked elastomers in aqueous,acidic,and basic environments.The elastomer possesses a tensile strength of 6.7 MPa and a strain at break of 1400%,which is superior to the existing waterproof selfhealing elastomers.The strain sensors and dielectric actuators based on the elastomer are highly stable and self-healable,even in extremely harsh environments.This design strategy of hydrophobic protection for dynamic interactions is quite general,allowing it to be extended to other self-healing materials.
