Aerogels are widely used as thermal insulation materials because of their high porosity and low bulk density.However,the insulation performance of aerogels is limited to a narrow temperature range.Besides,the preparat...Aerogels are widely used as thermal insulation materials because of their high porosity and low bulk density.However,the insulation performance of aerogels is limited to a narrow temperature range.Besides,the preparation of aerogel materials with precisely controlled and complex architectures is still challenging.Here,we report 3D printed polyimide/silica aerogel particle(PI/SAP)composite aerogels for thermal insulation in a wide range of temperature with customized applications.The printability and shape fidelity of 3D printed composite aerogels is improved by adding hydrophilic SAP as a rheology modifier.The resulting PI/SAP composite aerogel exhibits excellent flame-retardant properties and thermal insulation from-50℃ to 1300℃.Moreover,the PI/SAP composite aerogel with customized shape can be applied for battery insulation at subzero temperatures,promising to be used as customizable and stable insulating materials in a variety of complex and extreme applications.展开更多
Researching and manufacturing materials that possess both electromagnetic interference(EMI)shielding and infrared stealth capabilities is of great significance.Herein,an ultrathin polyimide-based nonwoven fabric with ...Researching and manufacturing materials that possess both electromagnetic interference(EMI)shielding and infrared stealth capabilities is of great significance.Herein,an ultrathin polyimide-based nonwoven fabric with low-reflection EMI shielding/infrared stealth performance is successfully fabricated by in-situ loading of Fe_(3)O_(4)/Ag nanoparticles on the surface of polyimide(PI)fiber(PFA),and followed by bonding with a commercial Cu/Ni mesh.The synergistic assembly of PFA and Cu/Ni promotes the rational construction of hierarchical impedance matching,inducing electromagnetic waves(EMW)to enter the composite and be dissipated as much as possible.Meanwhile,the existence of Cu/Ni mesh on back of PFA facilitates the formation of electromagnetic resonance and destructive interference of EMW reflected from composite,leading to a lowerreflectivity(0.26)EMI shielding performance of 58 dB within 24–40 GHz at a thinner thickness(430μm).More importantly,the fluffy PFA nonwoven fabric and metal Cu/Ni mesh endow composite with good thermal insulation and low infrared emissivity,resulting in excellent infrared stealth performance in various environments.As a result,such excellent compatibility makes it possible to become a promising defense material to be applied in military tent for preventing electromagnetic and infrared radiation.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2022YFB3805700)the National Natural Science Foundation of China(Nos.52073053 and 52233006)+2 种基金Young Elite Scientists Sponsorship Program by CAST(No.2021QNRC001)Shanghai Rising-Star Program(No.21QA1400300)Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-03-E00108)。
文摘Aerogels are widely used as thermal insulation materials because of their high porosity and low bulk density.However,the insulation performance of aerogels is limited to a narrow temperature range.Besides,the preparation of aerogel materials with precisely controlled and complex architectures is still challenging.Here,we report 3D printed polyimide/silica aerogel particle(PI/SAP)composite aerogels for thermal insulation in a wide range of temperature with customized applications.The printability and shape fidelity of 3D printed composite aerogels is improved by adding hydrophilic SAP as a rheology modifier.The resulting PI/SAP composite aerogel exhibits excellent flame-retardant properties and thermal insulation from-50℃ to 1300℃.Moreover,the PI/SAP composite aerogel with customized shape can be applied for battery insulation at subzero temperatures,promising to be used as customizable and stable insulating materials in a variety of complex and extreme applications.
基金National Natural Science Foundation of China(Nos.52373077,52003106,and 52161135302)the Research Foundation Flanders(No.G0F2322N)+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX23_1236)the Innovation Program of Shanghai Municipal Education Commission(No.2021-01-07-00-03-E00108).
文摘Researching and manufacturing materials that possess both electromagnetic interference(EMI)shielding and infrared stealth capabilities is of great significance.Herein,an ultrathin polyimide-based nonwoven fabric with low-reflection EMI shielding/infrared stealth performance is successfully fabricated by in-situ loading of Fe_(3)O_(4)/Ag nanoparticles on the surface of polyimide(PI)fiber(PFA),and followed by bonding with a commercial Cu/Ni mesh.The synergistic assembly of PFA and Cu/Ni promotes the rational construction of hierarchical impedance matching,inducing electromagnetic waves(EMW)to enter the composite and be dissipated as much as possible.Meanwhile,the existence of Cu/Ni mesh on back of PFA facilitates the formation of electromagnetic resonance and destructive interference of EMW reflected from composite,leading to a lowerreflectivity(0.26)EMI shielding performance of 58 dB within 24–40 GHz at a thinner thickness(430μm).More importantly,the fluffy PFA nonwoven fabric and metal Cu/Ni mesh endow composite with good thermal insulation and low infrared emissivity,resulting in excellent infrared stealth performance in various environments.As a result,such excellent compatibility makes it possible to become a promising defense material to be applied in military tent for preventing electromagnetic and infrared radiation.