2023Tr?ger’s Base (TB)-Based Polyimides as Promising Heat-Insulating and Low-K Dielectric Materials
作者：Jian Lu, Yu Zhang, Jing Li, Meifang Fu, Guoxiang Zou*, Shinji Ando, and Yongbing Zhuang*
关键字：polyimides, heat-insulating polymers, low-k dielectric materials
论文来源：期刊
具体来源：Macromolecules, https://doi.org/10.1021/acs.macromol.2c02148
发表时间：2023年
随着5G时代的到来，电子产品向高频高速数字信号传输方向发展，集成电路的小型化和集成化使得芯片尺寸越来越小。随着芯片内部组件间的距离逐渐缩小，信号传输的延迟使得芯片的性能大大降低。作为集成电路主要的绝缘材料，常规PI薄膜的介电常数在3.0~3.5范围内，愈来愈无法满足高频率集成电路的性能要求。
高温隔热材料（薄膜或泡沫）在航空航天、建筑、阻燃和防火领域具有广泛的应用，例如用于储存和长途运输氢气或稀有气体的隔热薄膜和泡沫，其市场规模正在不断扩大。高性能隔热材料应具有良好的机械强度、低导热性、低密度和优异的耐高温和低温性。例如，消防设备要求重量轻、隔热性好，从而减轻消防设备的重量，这将提高消防设备的性能和消防操作的成功率。PI基的隔热材料因其轻质、良好的机械和耐热性能等优点而备受关注。然而，传统的PI膜的面外导热系数为0.1-0.5 W/（mK），隔热和保温性能有待提高。
朝格尔碱基（Tro?ger’s base (TB)）是刚性的v形桥联双环连接基团，研究人员将其引入到聚酰亚胺（PI）主链中，制备了基于TB的聚酰亚胺（PI-TB-B和PI-TB-P)，调查了PI的结构和性能（包括折射率、面内/外双折射、透明性、导热系数和介电性能等，构建了PI的分子结构与导热系数和介电性质（低频率（1 kHz~1MHz）和高频（10 GHz）条件）等物理性质之间的相关性。TB基PI膜在10GHz下表现出低介电常数（Dk＝2.25-2.80）。特别地，PI-TB-N在10GHz下显示出超低的Dk＝2.25，这低于商业化Kapton（PMDA-ODA，Dk＞3.5）、6FDA基（Dk＝2.37-2.95）、BPADA基（Dk=2.83-3.18）、酯基（Dk=2.44-3.26）PI和其他低介电聚合物，包括聚醚（PES，Dk≈2.4），聚（亚苯基醚）（PPEs，Dk＝2.4-2.6）和苯并环丁烯（BCB）基聚合物（Dk＝2.6-2.8）等。
另外，这些PI也表现优异的隔热性，与商业聚酰亚胺膜 Kapton（0.240 W/mK）相比，它们具有超低的导热系数（λ＝0.035-0.145 W/m K）。所有TB基PI膜的λ值均低于0.145W/（mK），远低于商业Kapton（PMDA-ODA，λ=0.16-0.25W/（mK）（文献）和λ=0.240W/（mK）（本研究））以及其他报道的PI膜（λ=0.15-0.26W/（mK）的导热系数。值得一提的是，其中，PI-TB-P显示出超低的λ值（0.035W/（mK）），仅为商业膜 Kapton的1/8，这是迄今为止报道的所有PI薄膜中最低的λ值，表明TB基的PI膜作为隔热材料的潜在应用前景。
研究还结合PI分子结构参数的计算，系统考察了将TB结构引入PI主链对聚集态结构和物理性质的影响。这项工作为隔热和低介电PI材料的分子结构设计提供了新的思路。
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随着5G时代的到来，电子产品向高频高速数字信号传输方向发展，集成电路的小型化和集成化使得芯片尺寸越来越小。随着芯片内部组件间的距离逐渐缩小，信号传输的延迟使得芯片的性能大大降低。作为集成电路主要的绝缘材料，常规PI薄膜的介电常数在3.0~3.5范围内，愈来愈无法满足高频率集成电路的性能要求。
高温隔热材料（薄膜或泡沫）在航空航天、建筑、阻燃和防火领域具有广泛的应用，例如用于储存和长途运输氢气或稀有气体的隔热薄膜和泡沫，其市场规模正在不断扩大。高性能隔热材料应具有良好的机械强度、低导热性、低密度和优异的耐高温和低温性。例如，消防设备要求重量轻、隔热性好，从而减轻消防设备的重量，这将提高消防设备的性能和消防操作的成功率。PI基的隔热材料因其轻质、良好的机械和耐热性能等优点而备受关注。然而，传统的PI膜的面外导热系数为0.1-0.5 W/（mK），隔热和保温性能有待提高。
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随着5G时代的到来，电子产品向高频高速数字信号传输方向发展，集成电路的小型化和集成化使得芯片尺寸越来越小。随着芯片内部组件间的距离逐渐缩小，信号传输的延迟使得芯片的性能大大降低。作为集成电路主要的绝缘材料，常规PI薄膜的介电常数在3.0~3.5范围内，愈来愈无法满足高频率集成电路的性能要求。
高温隔热材料（薄膜或泡沫）在航空航天、建筑、阻燃和防火领域具有广泛的应用，例如用于储存和长途运输氢气或稀有气体的隔热薄膜和泡沫，其市场规模正在不断扩大。高性能隔热材料应具有良好的机械强度、低导热性、低密度和优异的耐高温和低温性。例如，消防设备要求重量轻、隔热性好，从而减轻消防设备的重量，这将提高消防设备的性能和消防操作的成功率。PI基的隔热材料因其轻质、良好的机械和耐热性能等优点而备受关注。然而，传统的PI膜的面外导热系数为0.1-0.5 W/（mK），隔热和保温性能有待提高。
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The correlations between the molecular structures of
four Tro?ger’s base (TB)-based polyimides (PIs) and two non-TB
containing analogues and physical properties including thermal conductivity (λ) and dielectric
properties both at low- and high-frequencies were investigated in detail. The
TB-based PI films exhibited low dielectric constants (Dk=2.25-2.80)
at 10 GHz. They possessed much lower λ values (0.035-0.145 W/mK) compared to the
commercial PI Kapton (0.240 W/mK). The influences of incorporating TB units into chain backbones on
aggregation structures and physical properties of PIs were identified. Incorporating TB units into chain backbones
effectively reduced the degree of chain orientation and increased fractional
free volume, leading to both low Dk and low λ values for the resulting PI films. Also,
introducing TB units enhanced molecular weights, toughness, and
glass-transition temperature (Tg) of the resulting
PIs. Therefore, the TB-based PIs can be promising as heat-insulating and low-k
dielectric materials.
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The correlations between the molecular structures of
four Tro?ger’s base (TB)-based polyimides (PIs) and two non-TB
containing analogues and physical properties including thermal conductivity (λ) and dielectric
properties both at low- and high-frequencies were investigated in detail. The
TB-based PI films exhibited low dielectric constants (Dk=2.25-2.80)
at 10 GHz. They possessed much lower λ values (0.035-0.145 W/mK) compared to the
commercial PI Kapton (0.240 W/mK). The influences of incorporating TB units into chain backbones on
aggregation structures and physical properties of PIs were identified. Incorporating TB units into chain backbones
effectively reduced the degree of chain orientation and increased fractional
free volume, leading to both low Dk and low λ values for the resulting PI films. Also,
introducing TB units enhanced molecular weights, toughness, and
glass-transition temperature (Tg) of the resulting
PIs. Therefore, the TB-based PIs can be promising as heat-insulating and low-k
dielectric materials.