The design of flexible polymeric films with internal porous structures has received increasing atten-tion in low dielectric applications.The highly porous metal-organic frameworks(MOFs)of[Cu3(BTC)2]n(BTC=benzene-1,3,5-tricarboxylate)were introduced into aramid nanofibers(ANF)matrix by using car-boxylated cellulose nanofibrils(CNF)as carriers to obtain strong,flexible,and ultra-low dielectric films.The well-dispersed"flowers-branch"like CNF@CuBTC through in-situ growth of CuBTC on CNF surface endowed the ANF/CNF@CuBTC films with excellent thermal stability,mechanical integrity and low dielec-tric properties.Besides,the flexible dielectric films exhibited superior ultraviolet(UV)resistance,lower coefficient of thermal expansion(4.28×10-5℃-1)and increased water contact angle(83.81°).More in-terestingly,the removal of guest molecules from the ANF/CNF@CuBTC films according to the vacuum heat treatment(VHT)process significantly improved their dielectric response.The specific surface areas of the composite films after VHT increased obviously,and the dielectric constant and dielectric loss tangent de-creased to the expected 1.8-2.2 and 0.001-0.03 at 100 MHz,respectively.Consequently,such designable ultra-low dielectric films with high flexibility play an incredible significance in applications of microelec-tronics under large deformation conditions,especially in flexible/wearable devices at the arrival of 5 G era.

Rui Liu;Xiang He;Miao Miao;Shaomei Cao;Xin Feng

Department of Chemistry,College of Sciences,Shanghai University,Shanghai 200444,China;Research Center of Nano Science and Technology,College of Sciences,Shanghai University,Shanghai 200444,China

材料科学技术（英文版）

[1]Rui Liu;Xiang He;Miao Miao;Shaomei Cao;Xin Feng-.In-situ growth of porous Cu3(BTC)2 on cellulose nanofibrils for ultra-low dielectric films with high flexibility)[J].材料科学技术（英文版）,2022(17):202-211

tricarboxylate,boxylated,CuBTC,VHT

In,situ,growth,porous,Cu3,cellulose,nanofibrils,dielectric,films,flexibility,flexible,polymeric,internal,structures,has,received,increasing,atten,applications,highly,metal,organic,frameworks,MOFs,benzene,were,introduced,into,aramid,nanofibers,ANF,matrix,by,using,CNF,carriers,obtain,strong,well,dispersed,flowers,branch,like,through,surface,endowed,excellent,thermal,stability,mechanical,integrity,properties,Besides,exhibited,superior,ultraviolet,UV,resistance,coefficient,expansion,increased,water,contact,angle,More,terestingly,removal,guest,molecules,from,according,vacuum,heat,treatment,process,significantly,improved,their,response,specific,areas,composite,after,obviously,constant,loss,tangent,expected,MHz,respectively,Consequently,such,designable,play,incredible,significance,microelec,tronics,under,large,deformation,conditions,especially,wearable,devices,arrival,era

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