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Detailed Program
Paper Number : NA-O04
Time Frame : 14:32~14:44
Presentation Date : Friday, 28, November
Session Name : Nano-particles & Nano-structured Materials
Session Chair 1# : Hae Jin Hwang
Session Chair 2# : Tohru Sekino
Three-Dimensional Structural control of insulating BN assembles in Polymer-nanocomposites
Hong-Baek CHO
Nagaoka University of Technology
Keywords: Polymer-nanocomposites, Boron Nitride, 3-dimensional control, Linear assembly, structural control

Distribution of insulating boron nitride (BN) nanoceramics are 3-dimensionally (3-D) controlled in polymer-nanocomposite films by electric field inducement. BN nanosheets, pretreated by exfoliation and functionalization of the surface were homogeneousely distributed in polysiloxane pre-polymer and they are redistributed by application of switching nanosec pulse electric field until the crosslinking of the prepolymer. A Si-micromold with micro-protrusions on the surface was used as an electrode in order to generate the electric concentration and to control the localization of the BN assembly during the application of electric field. The coordination effects of electric concentration, di-polarization, static energy, surface modification and Columbic attraction are considered as main factors that determine the controlled BN assembly. The application of nanosecond pulse-wise electric field and its¡¯ switching was adapted to overcome the electric field limitation, which is generated during application of DC electric field. The hexagonal-BN(h-BN), which is famous for its thermal anisotropy; when the h-BN are aligned perpendicular to the c-axis, their thermal conductivity increases by 20 times to 600 W/mK, compared to 30 W/mK that aligned parallel to the c-axis, is used as an insulating fillers. The structural analysis are performed three dimensionally using 3-D X-ray CT scanning. Analysis by scanning electron microscope, transmittance electron microscope and X-ray diffraction are used to evaluate enhancement of anisotropic orientation and structural assembly of BN nanosheets. Thermal conductivity and electric resistivity of the composites are assessed. The controlled fabrication of the 3-D BN assembles may give a way for developing 3-D thermal circuits as thermal interface materials in micro- and nano-electronics, such as, semiconductor, automobile, and aerospace industries. Figure 1 shows BN nanosheets assembly incorporated in polymer-nanocomposites films.
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