1. APTES-BNNs / Epoxy Composites
Silane treated h-BN for improved thermal conductive epoxy composite for Thermal interface materials (TIMs).
Hyung-Guen Kimb , Cheol-Min Yangc , Yun Seon Leec , M. Wasim AKhtara , Jong Seok Kima and Youn Sop Kimb*
a School of Chemical Engineering, Chonbuk National University
b Department of Chemical and Biomolecular Engineering, Chonnam National University
c Carbon Convergence Materials Research Center Korea Institute of Science and Technology (KIST)
Introdution
FT-IR
FT-IR spectra of (a) raw h-BN (b) oxidized h-BNNs (c) APTES-BNNs
Thermal conductivity of polymer matrix is very low, it’s not dissipate the heat generated in such devices effectively. TIMs are based on polymer resins that are loaded with thermally conductive filler material.
In this study, hexagonal boron nitride (h-BNs) was chosen as a thermally conducting filler due to its high thermal conductivity, chemical stability and electrical insulation properties. It has high K and high surface area when exfoliated.
In order to reduce interfacial resistance BN has been surface- modified using silane. Silane treatment was used to 3- Aminopropyltriethoxysilane (APTES).
(a)
Transmittance
(b)
(c)
4000
3500
3000
2500
2000
1500
1000
500
Wavenumber (cm-1)
Experimental
APTES-BNNs / Epoxy Composites
SEM
SEM micrographs of epoxy and silane functionalized h-BNNs/epoxy composites.
(a) epoxy matrix, (b) h-BNNs/epoxy, (c) APTES-BNNs/epoxy
Exfoliation of h-BNs in IPA using Probe Sonicator
Oxidation
( 6M H2SO4 + 2M HNO3 )
Reaction condition, 24h at 70℃
Preparation of solution
(APTES 5 wt%+NMP)
Reaction condition, 24h at 110 ℃
APTES-BNNs/epoxy composites
Drying after washing
with DI water
Drying of APTES-BNNs
*IPA : isopropyl alcohol
(a)
(b)
(c)
Thermal conductivity
Thermal conductivity of (a) raw h-BN/epoxy composite, (b) BNNs/epoxy composite, (c) APTES-BNNs/epoxy composite as filler weight fraction.
(a) low-magnification TEM images of BNNs, (b) BNNs
(c) selected area image from BNNs (d) electron diffraction pattern BNNs
(e-f) HR-TEM images of layer BNNs at different exfoliation time (e) 1hour (f) 6hours.
HR-TEM 6
(a)
(b)
(c)
Thermal conductivity (W/mK) 5 4 3 2 1 5 10 15 20 25 30
(d)
(e)
(f)
Content(wt.%)
Conclusion
5 layers
15~20 layers
The silane functionalization is highly effective and improves compatibility of filler with matrix.
The silane attached BNNs promote well dispersed condition, which reduces phonon scattering at filler-matrix interface. These groups also create long-range conductive pathways, which help phonon to phonon energy transfer, as a result in improving thermal conductivity of the epoxy composite.
The in-plane thermal conductivity at high fraction of APTES-BNNs (30 wt%) was improved up to 5.16 W/mK, which was ~32 times higher than that of controlled epoxy (0.16 W/mK).
~0.35nm
Multi-Functional Hybrid Nano Material Laboratory , School of Chemical Engineering, Chonbuk National University