How to achieve synergistic improvement of permittivity(ε_(r))and breakdown strength(E_(b))is a huge challenge for polymer dielectrics.Here,for the first time,theπ-conjugated comonomer(MHT)can simultaneously promote ...How to achieve synergistic improvement of permittivity(ε_(r))and breakdown strength(E_(b))is a huge challenge for polymer dielectrics.Here,for the first time,theπ-conjugated comonomer(MHT)can simultaneously promote theε_(r)and E_(b)of linear poly(methyl methacrylate)(PMMA)copolymers.The PMMA-based random copolymer films(P(MMA-co-MHT)),block copolymer films(PMMA-b-PMHT),and PMMA-based blend films were prepared to investigate the effects of sequential structure,phase separation structure,and modification method on dielectric and energy storage properties of PMMA-based dielectric films.As a result,the random copolymer P(MMA-coMHT)can achieve a maximumε_(r)of 5.8 at 1 kHz owing to the enhanced orientation polarization and electron polarization.Because electron injection and charge transfer are limited by the strong electrostatic attraction ofπ-conjugated benzophenanthrene group analyzed by the density functional theory(DFT),the discharge energy density value of P(MMA-co-PMHT)containing 1 mol%MHT units with the efficiency of 80%reaches15.00 J cm^(-3)at 872 MV m^(-1),which is 165%higher than that of pure PMMA.This study provides a simple and effective way to fabricate the high performance of polymer dielectrics via copolymerization with the monomer of P-type semi-conductive polymer.展开更多
基金the funding of National Key R&D Program of China(No.2020YFA0711700)Hunan National Natural Science Foundation(2021JJ30652)+3 种基金National Natural Science Foundation of China(52002404)Natural Science Foundation of Guangdong Province(2020A1515011198)Characteristic Innovation Projects of Colleges and Universities in Guangdong Province(2020KT SCX081)State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China
文摘How to achieve synergistic improvement of permittivity(ε_(r))and breakdown strength(E_(b))is a huge challenge for polymer dielectrics.Here,for the first time,theπ-conjugated comonomer(MHT)can simultaneously promote theε_(r)and E_(b)of linear poly(methyl methacrylate)(PMMA)copolymers.The PMMA-based random copolymer films(P(MMA-co-MHT)),block copolymer films(PMMA-b-PMHT),and PMMA-based blend films were prepared to investigate the effects of sequential structure,phase separation structure,and modification method on dielectric and energy storage properties of PMMA-based dielectric films.As a result,the random copolymer P(MMA-coMHT)can achieve a maximumε_(r)of 5.8 at 1 kHz owing to the enhanced orientation polarization and electron polarization.Because electron injection and charge transfer are limited by the strong electrostatic attraction ofπ-conjugated benzophenanthrene group analyzed by the density functional theory(DFT),the discharge energy density value of P(MMA-co-PMHT)containing 1 mol%MHT units with the efficiency of 80%reaches15.00 J cm^(-3)at 872 MV m^(-1),which is 165%higher than that of pure PMMA.This study provides a simple and effective way to fabricate the high performance of polymer dielectrics via copolymerization with the monomer of P-type semi-conductive polymer.
文摘目的:探讨3D打印技术制作的定位导板在上颌Le FortⅠ型截骨术中的应用效果。方法:选择牙颌面畸形患者8例,男4例,女4例;年龄18~32岁,平均24.6岁。所有患者术前均行头颅CT扫描,将CT数据导入Mimics16.0,重建出上颌骨和下颌骨的三维模型,用3-matic 9.0设计定位导板,在上颌Le Fort I型截骨线的上方骨壁厚的位置选4个点作为标志点,利用这4个标志点来定位上颌骨术后的位置,设计好后采用光敏树脂用三维打印机打印制作,在术中应用。结果:所有患者均采用新的方法行正颌手术,上颌骨模拟位置和术后实际位置绝对差异的平均值小于1mm,患者对术后美学效果均满意。结论:初步的结果显示此技术定位上颌骨精确,可在临床应用。
