Size: 2.7 + 0.5 nm

1. Mechanical Behavior of Integrated Polymer Nanocomposites 65 wt%, Fe2O3/PU SiC/PU Co THF +Co+2 + KAuCl4 25 wt%, Fe2O3/VE @10 K V V Co • ASTM D412 • Head Cross Speed: 15mm/min Au • SiC-PU more strengthened. • Functionalization effect: increased strength. • SIP method Fe2O3-PU: more flexible composite. Magnetic Behavior of Integrated Polymer Nanocomposites Fe2O3/VE Fe2O3/PU Fe/PU Fe2O3/PPy 25 wt% 65 wt% Hc=62 Oe Hc=63 Oe • Matrix effect: a significant effect. • Particle loading; • Composite matrix materials. • Functionalization: little effect; • Materials become harder after dispersion into polymer matrix. Hc=212 Oe Microstructure of Integrated Polymer Nanocomposites SEM Micrograph TEM Micrograph (450 oC) 65 wt%, Fe2O3/PU Fe2O3/VE Fe/PU as-rec. SIP DM func. • Functionalization: good dispersion.. • SIP favors particle dispersion. • Carbon-Fe composites. Fe2O3 NPs RT 7.3% n=2 Fe/VE Fe/PU A Nanoparticles Electrode Spin V CIP 5 um Magnetic Nonmagnetic Matrix H RT 8.4% • At RT: GMR = 7.3 % • At 130 K, GMR=14.2% • At RT: GMR = 8.4% • Particle loading effect Fe/PE Particulate Magnetic Nanocomposites for Electronic Device Applications Zhanhu Guo and H. Thomas Hahn Multifunctional Composites Lab, Mechanical & Aerospace Engineering Department and Materials Science & Engineering Department University of California Los Angeles, Los Angeles, CA 90095, USA INTRODUCTION Polymeric composites reinforced with inorganic fillers have attracted much interest due to their reduced weight, high homogeneity, cost-effective processability and tunable physical such as mechanical, magnetic, optical, electric and electronic properties. The applications have extended into the marine (Naval submarine) and airplane (Boeing 787) industries. Furthermore, Particulate Co-Au Nanocomposite Application: GMR Sensor • Core-shell Fabrication • TEM micrograph • GMR Performance Test • Thermodynamic Analysis • Anodic reaction: • Co Co2++2e- ε0= - 0.277 V (1) • Cathodic reaction: • Au3++3e-Au ε0=1.401 V (2) • 3Co+2Au3+3Co2++2Au(3) • G3=3G1+2G2= - 10.068 F Furthermore, nanoparticles (NPs) within the polymeric matrix render the nanocomposite potential electronic device applications such as fuel cells, photovoltaic (solar) cells, batteries and magnetic data storage. On the other side, the functional groups of the polymer surrounding the nanoparticles enable these polymer nanocomposites suitable for variable applications such as site-specific molecule targeting application in the biomedical areas. • Metallic conduction behavior • Possible due to small spacer distance • Size: 2.7 + 0.5 nm Particle dispersion together with the interaction between fillers and polymer matrix are major challenges in the polymer composite manufacturing. The particle agglomerates and voids resulting from the poor bondage will serve as defect generating a deleterious physical properties such as lower tensile strength for structural material application and poorer electron transport path for integrated polymer composite electric/electronic device applications. We have demonstrated strengthened polymer nanocomposite fabrication by surface engineering the particles. However, functionalization is an extra cost for production with high particle loading. We developed several simple and low-cost methods (surface-initiated-polymerization, monomer stabilization method, and solvent-extraction approach). Polymer nanocomposites were developed into a granular giant magnetoresistance (GMR) sensor with the highest signal among these systems. Compared with metallic matrix GMR, the polymer matrix could be facile fabrication, low-cost usage without any packaging requirement and suitable for harsh environmental applications, ready to be used in specific biomedical areas. Microwave absorber were built up from the polymer nanocomposites. The device shows weight reduction and fairly well performance. GMR Sensor Application Nanocomposite Fabrication Methodology • Composite Fabrication with Coupling Agent • Vinyl ester (VE) resin: matrix Advantage of Polymer Nanocomposite Sensor Chemical structure of (A) styrene (B) vinyl ester monomer • Easy fabrication • Light-weight • Stability • No need for extra package • Ready to be used in biomedical engineering • Iron oxide (Fe2O3) nanoparticles: 23 nm Particulate Polymer Nanocomposite Application: Microwave Absorber • Methacryloxypropyltrimethoxysilane (MPS): coupling agent Microwave absorber dimensions outer diameter: 7.00 mm inner diameter: 3.04 mm • Nanoparticle functionalization Particulate Nanocomposite Application: GMR Sensor Z: impedance; d: thickness λ: wavelength in free space MBRL: metal back reflection loss • GMR Operation Principle • GMR Sensor Evaluation Fe/PU Bold line: real Thin line: imaginary • Condition: tetrahydrofuran and ultrasonication • Advantage: protecting NPs from dissolution; introduce C=C for covalent bondage • Disadvantage: still need organic solvent anti-parallel: high R parallel: low R • Surface-Initiated-Polymerization (SIP) • GMR Geometry and Measurement catalyst + promoter + ultrasoincation nanoparticle activation • lower Permeability • Low magnetization • Higher Permitivity • Presence of oxide in Fe particles • Formation of particle-chain • Weight reduction of 38 % for discrete frequency at 10 GHz • Potential to save weight with improved metal NPs • Suitable for oxide nanoparticles • Advantage: no need for coupling agent • Conduction Mechanism Concluding Remarks • Surface-initiated-polymerization approach to fabricate the polymer nanocomposite • Monomer stabilization method to manufacture the polymer nanocomposites • Unique magnetic property in the polymer nanocomposite system • Successful demonstration of GMR sensor fabricated from polymer nanocomposite • Polymer nanocomposite based microwave absorber with significant weight reduction • Monomer Stabilization Method (MSM) • GMR Calculation Fe NPs Monomer serves as a surfactant VE • Related Publication • Z. Guo, et al., Journal of Materials Chemistry, 16, 2800-2808 (2006). • Z. Guo, et al., Journal of Materials Chemistry, 17, 806-813 (2007) • Z. Guo,. et al, Nanotechnology, 18, 335704 (2007) • Z. Guo, et al., Composites Science and Technology, 68, 164-170 (2008) • Z. Guo, et all, Electrochemical and Solid State Letters, 10(12) E31-E35 (2007) • Z. Guo, et al., Applied Physics Letter, 90, 053111 (2007) • Z. Guo, et al., Journal of Applied Physics, 10, 09M511 (2007) • Z. Guo, et al., Journal of the Electrochemical Society, 151 (1), D1-D5 (2005) R(0) and R(H): resistance at zero and any applied field H. • Conduction Mechanism Prospectus • Improve the sensitivity of GMR sensor • Fabricate GMR sensor prototype • Increase the microwave bandwidth • Conductive polymer based nanocomposite PU • n=2, the conduction is hopping mechanism; • n=4, quasi three-dimensional variable range hopping. • Suitable for metal nanoparticles • Advantage: no need for coupling agent • Hopping/tunneling mechanism.