Wei Shiyang, Yu Qiaoxi, Fan Zhenguo, Liu Siwei, Chi Zhenguo, Chen Xudong, Zhang Yi, Xu Jiarui
PCFM Lab, GD HPPC Lab, Guangdong Engineering Technology Research Centre for High-performance Organic and Polymer Photoelectric Functional Films, State Key Laboratory of Optoelectronic Materials and Technologies, Materials Science Institute, School of Chemistry, Sun Yat-sen University Guangzhou 510275 China
RSC Adv. 2018 Jun 15;8(39):22169-22176. doi: 10.1039/c8ra00827b. eCollection 2018 Jun 13.
The preparation of polymeric composite materials with low filler content as well as high thermal conductivity has been an important subject for the field of polymer material research. During our recent investigation on polyimide (PI), it was found that poly(amic acid) (PAA) solution (in dimethylacetamide, DMAc) could crystallize at low temperature. When adding reduced graphene oxide (rGO) as the thermal conductive fillers in the PAA solution, it was also found that the crystallization process of PAA would impel the rGO to rearrange in order and form an aligned thermal conductive network. To retain the rGO network structure, the freeze-drying technique was used to remove the solvent. Subsequently, through a thermal imidization process the final rGO/PI films containing a 3D rGO network could be obtained. The PI composite films retain good flexibility, excellent thermal stability, and exhibit excellent thermal conductivity. When the content of rGO added is 8 wt%, the thermal conductivity of the rGO/PI film can reach a high value of 2.78 W m K, which is about 15.4 times that of neat PI and 5.5 times that of the rGO/PI composite film prepared by the conventional two-step routine with the same content of rGO.
制备具有低填料含量和高导热率的聚合物复合材料一直是聚合物材料研究领域的一个重要课题。在我们最近对聚酰亚胺（PI）的研究中，发现聚酰胺酸（PAA）溶液（在二甲基乙酰胺，DMAc中）在低温下会结晶。当在PAA溶液中添加还原氧化石墨烯（rGO）作为导热填料时，还发现PAA的结晶过程会促使rGO有序重排并形成排列整齐的导热网络。为了保留rGO网络结构，采用冷冻干燥技术去除溶剂。随后，通过热亚胺化过程可以获得含有3D rGO网络的最终rGO/PI薄膜。PI复合薄膜保持良好的柔韧性、优异的热稳定性，并表现出优异的导热率。当添加的rGO含量为8 wt%时，rGO/PI薄膜的导热率可达到2.78 W m K的高值，约为纯PI的15.4倍，是采用相同rGO含量的传统两步法制备的rGO/PI复合薄膜的5.5倍。
