An Insight into the Directional Thermal Transport of Hexagonal Boron Nitride Composites.

Ideal dielectric materials for microelectronic devices should have high directionally-tailored thermoconductivity with low dielectric constant and loss. Hexagonal boron nitride (hBN) with excellent thermal and dielectric properties shows promise for fabrication of thermoconductive dielectric polymer composites. Herein, a simple method for fabrication of lightweight polymer/hBN composites with high directionally-tailored thermoconductivity and excellent dielectric properties is presented. The solid polymer/hBN composites are manufactured by melt-compounding and injection molding. The porous composites are successfully manufactured in an injection molding process through supercritical fluid (SCF) foaming. X-ray tomography provides direct visualization of the internal microstructure and hBN orientation leading to an in-depth understanding of the directionally-dependent thermoconductivity of the polymer/hBN composites. Shear-induced orientation of hBN platelets in the solid HDPE/hBN composites leads to significant anisotropic thermal conductivity. The solid HDPE/23.2 vol.% hBN composites show an in-plane thermoconductivity as high as 10.1 W m-1 K-1 while the through-plane thermoconductivity is limited to 0.28 W m-1 K-1. However, the generation of a porous structure via SCF foaming imparts in situ exfoliation, random orientation and interconnectivity of hBN platelets within the polymer matrix. This results in highly isotropic thermoconductivity with higher bulk thermal conductivity in the lightweight porous composites as compared to their solid counterparts. Furthermore, the electrically insulating composites developed in this study exhibit low dielectric constant and ultralow dielectric loss. Thus, this study presents a simple fabrication method to develop lightweight dielectric materials with tailored thermal conductivity for modern electronics.

[1]  Jie Yuan,et al.  Highly Thermally Conducting Polymer-Based Films with Magnetic Field-Assisted Vertically Aligned Hexagonal Boron Nitride for Flexible Electronic Encapsulation. , 2019, ACS applied materials & interfaces.

[2]  Hao Bai,et al.  An Anisotropically High Thermal Conductive Boron Nitride/Epoxy Composite Based on Nacre‐Mimetic 3D Network , 2019, Advanced Functional Materials.

[3]  Yanhui Chen,et al.  Highly anisotropic thermally conductive polyimide composites via the alignment of boron nitride platelets , 2019, Composites Part B: Engineering.

[4]  Xingyi Huang,et al.  Highly Thermally Conductive Yet Electrically Insulating Polymer/Boron Nitride Nanosheets Nanocomposite Films for Improved Thermal Management Capability. , 2018, ACS nano.

[5]  Kaichang Kou,et al.  Enhanced through-plane thermal conductivity of PTFE composites with hybrid fillers of hexagonal boron nitride platelets and aluminum nitride particles , 2018, Composites Part B: Engineering.

[6]  R. Sun,et al.  Effect of chemical functionalization on the thermal conductivity of 2D hexagonal boron nitride , 2018, Applied Physics Letters.

[7]  Xingyou Tian,et al.  Fabrication of Thermal Conductivity Enhanced Polymer Composites by Constructing an Oriented Three-Dimensional Staggered Interconnected Network of Boron Nitride Platelets and Carbon Nanotubes. , 2018, ACS applied materials & interfaces.

[8]  Chul B. Park,et al.  Enhanced Electrical and Electromagnetic Interference Shielding Properties of Polymer-Graphene Nanoplatelet Composites Fabricated via Supercritical-Fluid Treatment and Physical Foaming. , 2018, ACS applied materials & interfaces.

[9]  Xingyou Tian,et al.  Synergistic enhancement of anisotropic thermal transport flexible polymer composites filled with multi-layer graphene (mG) and mussel-inspiring modified hexagonal boron nitride (h-BN) , 2018, Composites Part A: Applied Science and Manufacturing.

[10]  S. N. Leung,et al.  Thermally conductive polybutylene terephthalate/hexagonal boron nitride composites with bimodal filler size distribution , 2018, Materials Chemistry and Physics.

[11]  Jun Zhang,et al.  Polymer composites based on hexagonal boron nitride and their application in thermally conductive composites , 2018, RSC advances.

[12]  Y. Bando,et al.  Densely Interconnected Porous BN Frameworks for Multifunctional and Isotropically Thermoconductive Polymer Composites , 2018, Advanced Functional Materials.

[13]  Chul B. Park,et al.  Ultralight Microcellular Polymer-Graphene Nanoplatelet Foams with Enhanced Dielectric Performance. , 2018, ACS applied materials & interfaces.

[14]  Q. Xie,et al.  Dielectric properties and thermal conductivity of epoxy composites using core/shell structured Si/SiO2/Polydopamine , 2018 .

[15]  M. L. Van de Put,et al.  Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk , 2018, npj 2D Materials and Applications.

[16]  Chul B. Park,et al.  Enhanced Thermal Conductivity of Graphene Nanoplatelet-Polymer Nanocomposites Fabricated via Supercritical Fluid-Assisted in Situ Exfoliation. , 2018, ACS applied materials & interfaces.

[17]  He Sun,et al.  High-Efficient Liquid Exfoliation of Boron Nitride Nanosheets Using Aqueous Solution of Alkanolamine , 2017, Nanoscale Research Letters.

[18]  L. Turng,et al.  Sub-critical gas-assisted processing using CO2 foaming to enhance the exfoliation of graphene in polypropylene + graphene nanocomposites , 2017 .

[19]  Y. Bando,et al.  Multifunctional Superelastic Foam-Like Boron Nitride Nanotubular Cellular-Network Architectures. , 2017, ACS nano.

[20]  R. Gerhardt,et al.  Enhanced dielectric properties of polymer matrix composites with BaTiO3 and MWCNT hybrid fillers using simple phase separation , 2016 .

[21]  H. Okamoto,et al.  Facile Exfoliation and Noncovalent Superacid Functionalization of Boron Nitride Nanosheets and Their Use for Highly Thermally Conductive and Electrically Insulating Polymer Nanocomposites. , 2016, ACS applied materials & interfaces.

[22]  Bin Shen,et al.  Compressible Graphene-Coated Polymer Foams with Ultralow Density for Adjustable Electromagnetic Interference (EMI) Shielding. , 2016, ACS applied materials & interfaces.

[23]  Qiang Liu,et al.  Fabrication and properties of porous boron nitride/silicon oxynitride ceramic composites via gas pressure sintering , 2015 .

[24]  P. Valvin,et al.  Hexagonal boron nitride is an indirect bandgap semiconductor , 2015, Nature Photonics.

[25]  Guoqun Zhao,et al.  Enhancing Nanofiller Dispersion Through Prefoaming and Its Effect on the Microstructure of Microcellular Injection Molded Polylactic Acid/Clay Nanocomposites , 2015 .

[26]  Xiaobing Luo,et al.  Thermal Conductivity of Polymer-Based Composites with Magnetic Aligned Hexagonal Boron Nitride Platelets. , 2015, ACS applied materials & interfaces.

[27]  D. Adamson,et al.  PMMA functionalized boron nitride sheets as nanofillers. , 2015, Nanoscale.

[28]  M. Modesti,et al.  Characterization of porosity, structure, and mechanical properties of electrospun SiOC fiber mats , 2015, Journal of Materials Science.

[29]  R. Purushothaman.  Amine functionalized SBA-15/terpolyimide composites with low dielectric constant , 2015, Journal of Porous Materials.

[30]  Oren Regev,et al.  Thermally Conductive Graphene-Polymer Composites: Size, Percolation, and Synergy Effects , 2015 .

[31]  K. Goodson,et al.  Thermal transport: Cool electronics. , 2015, Nature materials.

[32]  C. Zhi,et al.  Thermally conductive, electrically insulating and melt-processable polystyrene/boron nitride nanocomposites prepared by in situ reversible addition fragmentation chain transfer polymerization , 2015, Nanotechnology.

[33]  P. Hodgson,et al.  High-Efficient Production of Boron Nitride Nanosheets via an Optimized Ball Milling Process for Lubrication in Oil , 2014, Scientific Reports.

[34]  Chul B. Park,et al.  Polypropylene/carbon nanotube nano/microcellular structures with high dielectric permittivity, low dielectric loss, and low percolation threshold , 2014 .

[35]  K. Moon,et al.  Exfoliated hexagonal boron nitride-based polymer nanocomposite with enhanced thermal conductivity for electronic encapsulation , 2014 .

[36]  K. Moon,et al.  Magnetic alignment of hexagonal boron nitride platelets in polymer matrix: toward high performance anisotropic polymer composites for electronic encapsulation. , 2013, ACS applied materials & interfaces.

[37]  Chul B. Park,et al.  Mechanisms of nanoclay-enhanced plastic foaming processes: effects of nanoclay intercalation and exfoliation , 2013, Journal of Nanoparticle Research.

[38]  Xingyi Huang,et al.  Fluoro-Polymer@BaTiO3 Hybrid Nanoparticles Prepared via RAFT Polymerization: Toward Ferroelectric Polymer Nanocomposites with High Dielectric Constant and Low Dielectric Loss for Energy Storage Application , 2013 .

[39]  S. Ando,et al.  Anisotropic thermal diffusivity of hexagonal boron nitride-filled polyimide films: effects of filler particle size, aggregation, orientation, and polymer chain rigidity. , 2013, ACS applied materials & interfaces.

[40]  C. Zhi,et al.  Polyhedral Oligosilsesquioxane‐Modified Boron Nitride Nanotube Based Epoxy Nanocomposites: An Ideal Dielectric Material with High Thermal Conductivity , 2013 .

[41]  Wei Zhang,et al.  Two-layer materials of polyethylene and a carbon nanotube/cyanate ester composite with high dielectric constant and extremely low dielectric loss , 2013 .

[42]  Jianfeng Zhang,et al.  Facile preparation of lightweight microcellular polyetherimide/graphene composite foams for electromagnetic interference shielding. , 2013, ACS applied materials & interfaces.

[43]  Junqing Hu,et al.  Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets , 2013, Nanoscale Research Letters.

[44]  Johannes E. Schindelin,et al.  Fiji: an open-source platform for biological-image analysis , 2012, Nature Methods.

[45]  Ya‐Ping Sun,et al.  Polymer/boron nitride nanocomposite materials for superior thermal transport performance. , 2012, Angewandte Chemie.

[46]  Xingyi Huang,et al.  A review of dielectric polymer composites with high thermal conductivity , 2011, IEEE Electrical Insulation Magazine.

[47]  E. Giannelis,et al.  Dielectric study of Poly(styrene-co-butadiene) Composites with Carbon Black, Silica, and Nanoclay , 2011 .

[48]  A. Balandin.  Thermal properties of graphene and nanostructured carbon materials. , 2011, Nature materials.

[49]  Yan Liu,et al.  A three-dimensional vertically aligned functionalized multilayer graphene architecture: an approach for graphene-based thermal interfacial materials. , 2011, ACS nano.

[50]  J. Velasco,et al.  Broad-band electrical conductivity of carbon nanofibre-reinforced polypropylene foams , 2011 .

[51]  N. Pu,et al.  Production of few-layer graphene by supercritical CO2 exfoliation of graphite , 2009 .

[52]  A. Hrymak,et al.  Improved through‐plane electrical conductivity in a carbon‐filled thermoplastic via foaming , 2008 .

[53]  Rodney S. Ruoff,et al.  Polymer−Graphite Nanocomposites:  Effective Dispersion and Major Property Enhancement via Solid-State Shear Pulverization , 2008 .

[54]  D. Baird,et al.  An improved technique for exfoliating and dispersing nanoclay particles into polymer matrices using supercritical carbon dioxide , 2007 .

[55]  Jason M. Keith,et al.  Measuring thermal conductivities of anisotropic synthetic graphite-liquid crystal polymer composites , 2006 .

[56]  Yi He,et al.  Rapid thermal conductivity measurement with a hot disk sensor: Part 1. Theoretical considerations , 2005 .

[57]  Takashi Taniguchi,et al.  Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal , 2004, Nature materials.

[58]  T. Kotaka,et al.  Biaxial Flow-Induced Alignment of Silicate Layers in Polypropylene/Clay Nanocomposite Foam , 2001 .

[59]  D.D.L. Chung,et al.  Increasing the thermal conductivity of boron nitride and aluminum nitride particle epoxy-matrix composites by particle surface treatments , 2000 .

[60]  Robert D. Miller.  In Search of Low-k Dielectrics , 1999, Science.

[61]  S. Gustafsson,et al.  THERMAL CONDUCTIVITY, THERMAL DIFFUSIVITY, AND SPECIFIC HEAT OF THIN SAMPLES FROM TRANSIENT MEASUREMENTS WITH HOT DISK SENSORS , 1994 .

[62]  S. Gustafsson.  Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials , 1991 .

[63]  Chul B. Park,et al.  A versatile foaming platform to fabricate polymer/carbon composites with high dielectric permittivity and ultra-low dielectric loss , 2019, Journal of Materials Chemistry A.

[64]  D. Xiong,et al.  Study on Mechanical, Thermal and Electrical Characterizations of Nano-SiC/Epoxy Composites , 2009 .

[65]  E. Maire,et al.  Characterization of the morphology of cellular ceramics by 3D image processing of X-ray tomography , 2007 .