3D Lamellar-Structured Graphene Aerogels for Thermal Interface Composites with High Through-Plane Thermal Conductivity a
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ARTICLE
Cite as Nano-Micro Lett. (2021) 13:22 Received: 17 August 2020 Accepted: 11 October 2020 © The Author(s) 2020
https://doi.org/10.1007/s40820-020-00548-5
3D Lamellar‑Structured Graphene Aerogels for Thermal Interface Composites with High Through‑Plane Thermal Conductivity and Fracture Toughness Pengfei Liu1,2, Xiaofeng Li1 *, Peng Min1, Xiyuan Chang2, Chao Shu1, Yun Ding1, Zhong‑Zhen Yu2,3 *
HIGHLIGHTS • Lamellar-structured graphene aerogels with vertically aligned and closely stacked high-quality graphene lamellae are fabricated. • The superior thermally conductive capacity of the aerogel endows epoxy with a high through-plane thermal conductivity of 20.0 W m−1 K−1 at 2.30 vol% of graphene content. • The nacre-like structure endows the epoxy composite with enhanced fracture toughness. ABSTRACT Although thermally conductive graphene sheets are efficient
in enhancing in-plane thermal conductivities of polymers, the resulting
~29.8 nm
nanocomposites usually exhibit low through-plane thermal conductivities,
closely stacked high-quality ultrathin graphene lamella
impregnation of epoxy
50 nm
limiting their application as thermal interface materials. Herein, lamellarstructured polyamic acid salt/graphene oxide (PAAS/GO) hybrid aerogels
he
at
are constructed by bidirectional freezing of PAAS/GO suspension followed yimide (PI), while GO is converted to thermally reduced graphene oxide (RGO) during thermal annealing at 300 °C. Final graphitization at 2800 °C converts PI to graphitized carbon with the inductive effect of RGO, and simultaneously, RGO is thermally reduced and healed to high-quality gra‑ phene. Consequently, lamellar-structured graphene aerogels with superior through-plane thermal conduction capacity are fabricated for the first time, and its superior through-plane thermal conduction capacity results from its
50 µm Lamellar structured graphene aerogel
sp
re
ad
Z
ing
Y
g
din
rea
t sp
hea
Graphene/epoxy composites
90 80 Temperature (°C)
by lyophilization. Subsequently, PAAS monomers are polymerized to pol‑
X
LED lamp
ΔT
70 60 Average ΔT ≈ 13.2 °C
50 40 30 20
LY-50X24-10W
Our work Silicone rubber
0
50
100 150 Time (s)
200
Thermal interface composite
Cu heat sink
250
vertically aligned and closely stacked high-quality graphene lamellae. After vacuum-assisted impregnation with epoxy, the resultant epoxy composite with 2.30 vol% of graphene exhibits an outstanding through-plane
thermal conductivity of as high as 20.0 W m−1 K−1, 100 times of that of epoxy, with a record-high specific thermal conductivity enhancement
of 4310%. Furthermore, the lamellar-structured graphene aerogel endows epoxy with a high fracture toughness, ~ 1.71 times of that of epoxy. KEYWORDS Anisotropic aerogels; Graphene; Thermal conductivity; Epoxy composites; Fracture toughness * Xiaofeng Li, [email protected]; Zhong‑Zhen Yu, [email protected] 1 Beijing Key Laboratory of Advanced Functional Polymer Composites, Beijing University of Chemical Technology, Beijing 100029, People’s Re
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