In-situ growth of porous Cu_(3)(BTC)_(2) on cellulose nanofibrils for ultra-low dielectric films with high flexibility

作     者：Rui Liu Xiang He Miao Miao Shaomei Cao Xin Feng Rui Liu;Xiang He;Miao Miao;Shaomei Cao;Xin Feng

作者机构：Department of ChemistryCollege of SciencesShanghai UniversityShanghai 200444China Research Center of Nano Science and TechnologyCollege of SciencesShanghai UniversityShanghai 200444China 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2022年第112卷第17期

页      面：202-211页

核心收录：

学科分类：07[理学] 070205[理学-凝聚态物理] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 0822[工学-轻工技术与工程] 0702[理学-物理学] 

基　　金：financially sponsored by the Science and Technology Commission of Shanghai Municipality(nos.20230742300 and 18595800700)。 

主　　题：Aramid nanofibers Carboxylated cellulose nanofibrils Vacuum heat treatment Dielectric properties Metal-organic frameworks 

摘      要：The design of flexible polymeric films with internal porous structures has received increasing attention in low dielectric applications.The highly porous metal-organic frameworks(MOFs)of[Cu_(3)(BTC)_(2)]_(n)(BTC=benzene-1,3,5-tricarboxylate)were introduced into aramid nanofibers(ANF)matrix by using carboxylated cellulose nanofibrils(CNF)as carriers to obtain strong,flexible,and ultra-low dielectric films.The well-dispersed“flowers-branchlike CNF@CuBTC through in-situ growth of CuBTC on CNF surface endowed the ANF/CNF@Cu BTC films with excellent thermal stability,mechanical integrity and low dielectric 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 interestingly,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 decreased 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 microelectronics under large deformation conditions,especially in flexible/wearable devices at the arrival of 5 G era.