原位制备低掺杂高导热聚酰亚胺纳米复合薄膜研究

In-Situ Preparation of Low-Content Nano-Doped Polyimide Composite Films with High Thermal Conductivity

摘要:

导热聚合物材料广泛应用于各种电子设备和航空航天工业的热管理领域。添加高导热填料能改善聚合物材料固有的低导热系数，但高添加量会导致力学性能下降，限制其实际应用。因此，提高聚合物材料的导热系数并控制填料占比，以保留其良好的加工性与轻质性，成为该领域研究的热点。聚酰亚胺因其电绝缘性强、高热稳定性和优异的力学性能备受关注，然而，高填料占比会导致高成本和材料脆性等问题，难以满足实际生产需要。石墨烯以其大比表面积和优异导热性能，是导热填料的理想选择。提出了一种低含量（质量分数1%—5%）小片还原氧化石墨烯的掺杂策略，通过原位聚合制备聚酰亚胺导热复合薄膜。结果表明，利用改进Hummers法和差速离心法后还原制备的小片还原氧化石墨烯形成了有效的高导热碳纳米网络，显著提高了聚酰亚胺复合薄膜的热稳定性、力学性能和导热率。与纯聚酰亚胺薄膜相比，制备得到的SRGO/PI-3薄膜弹性模量提高了20.0%，SRGO/PI-5薄膜硬度提高了19.5%且导热率提高了3.35倍。这种低含量小片还原氧化石墨烯的掺杂策略，有望实现的高导热聚酰亚胺复合薄膜的大规模工业化制备和应用。

Abstract:

Thermal conductive polymer materials are widely used in the thermal management of various electronic devices and the aerospace applications. Enhancing the inherent low thermal conductivity of polymer materials by adding high thermal conductivity fillers often compromises their mechanical properties， limiting practical applications. Therefore， balancing improved thermal conductivity with the retention of flexible processability and lightweight is a key research focus. Polyimide is highly regarded for its strong electrical insulation， high thermal stability， and excellent mechanical properties. However， a high filler ratio can introduce issues such as increased cost， brittleness， and difficulty in meeting production needs. Graphene， with its large specific surface area and excellent thermal conductivity， it is a promising filler. However， high filler proportions （>10 wt%） can lead to stacking and agglomeration， negatively impacting the mechanical properties of composites. In this study， we propose a low content （1 wt% to 5 wt%） doping strategy using small pieces of reduced graphene oxide （SRGO） to prepare polyimide thermal conductive composite films via in-situ polymerization. Results show that the low-content SRGO， prepared using an improved Hummers method and differential centrifugal method prior to reduction， forms an effective carbon nanonetwork with high thermal conductivity. This significantly enhances the thermal stability， mechanical properties and thermal conductivity of PI composite films. In particular， its thermal conductivity is 4.35 times higher than that of pure PI films. Compared with hardness in pure polyimide films， the elastic modulus is up to 20.1% and 19.5% higher， respectively. This low-content SRGO doping strategy shows promise for the large-scale industrial preparation and application of high thermal conductivity PI composite films.