A Glimpse of Wang's
Research
Interests
The research interest of my group is to understand the fundamentals of synthesis, processing, and structure/property relations of soft matter and nanomaterials (polymers, colloids, lipids, gels, nanoparticles, carbon nanotubes, etc.) and explore novel applications of soft/nano materials. The current research topics include:
Materials and processing for flexible
electronics
Inkjet printing is among the most promising techniques that
are compatible with roll-to-roll (R2R) manufacturing of flexible and
large format electronics at very low cost. We aim at addressing key materials and
processing issues in inkjet printing fabrication of flexible electronics based
on functional organic materials and nanomaterials.
Carbon-nanotubes
at rest and in motion
Carbon nanotubes (CNTs) are structurally unique materials that exhibit
excellent mechanical, electrical, thermal, and optical properties, and they
offer the potential promise for a number of novel applications. We
are interested in synthesis, processing, properties and applications of carbon
nanotube materials.
Polymer thin films, surfaces and interfaces
Two fundamental thermodynamic factors arise at the nanoscale: (1) large surface
to volume ratio and (2) comparable fluctuation length to the object size.
Polymer thin films can possess both features, and are emerging at the frontier
of polymer science. Thin film morphology can be complex as a result of
multiple factors (confinement, surface interactions, interfacial instability,
etc.), multiple phase transitions (demixing, crystallization, wetting, etc.),
and their dynamic interplay. Technologically, the complex morphologies
are critical for some important applications of polymer films, such as for
automobile coating and electronics packaging. Our current work focuses on
surface critical phenomena, structural evolution under confinement and
instabilities in low dimensions.
Phase transformations in polymers
Di Marzio has identified ten classes of phase transitions, five related to
isolated polymer chains and the others to a collection of polymers. For
isolated polymer chains they are: (1) the collapse transition, (2) the helix to
random coil transition, (3) equilibrium polymerization in dilute solution, (4)
adsorption onto a surface, and (5) the polymer threading a membrane
transition. For collections of polymer they are: (6) polymer-polymer and
polymer solvent liquids, (7) crystallization, (8) liquid crystals and plastic
crystals, (9) glasses and gels, and (10) soap, block copolymers, membranes,
micelles and vesicles. A complete understanding of these phase
transitions is still far from complete. The interplay of two or more
transitions provides unlimited opportunities for scientific exploration.
Our current studies focus on the early stages of crystallization and the
interplay between phase separation and crystallization in polymer blends.
Biomimetic lipids systems
Lipids are amphiphilic molecules (i.e., part of a molecule is hydrophilic and
part is hydrophobic) and are one of the principal components of various
membranes of biological cells. When dispersed in water, the amphiphilic
nature of lipid molecules leads to the formation of a variety of ordered and
disordered phases. Lamellar stacks, unilamellar and multilamellar
vesicles, rods, and bilayered micelles (known as “bicelles”) are
commonly found self-organized structures. The bicelles are particularly
interesting because they are magnetically alignable for solid state NMR studies
of membrane peptides and proteins. We are interested in the kinetics of
phase transition from one structure to another using time-resolved small angle
neutron scattering (TR-SANS) and X-ray scattering. Our current work
focuses on the bicelle to the lamellae transition.
(All downloadable materials on this webpage are available for personal use only, and in accordance with the copyright laws that apply.)
Carbon-nanotubes
Wang, H., Xu, Z. Y., Eres, G., “Order in Vertically Aligned Carbon Nanotubes”, Appl. Phys. Lett., 88, 213111 (2006). PDF
Fry, D., Langhorst, B., Wang, H., Becker, M., Bauer, B. J., Grulke, E., Hobbie, E. K., “Rheo-optical Studies of Carbon Nanotube Suspensions”, J. Chem. Phys, 124, 054703 (2006). PDF
Wang, H., Christopherson, G. T., Xu, Z., Porcar, L., Ho, D., Fry, D., Hobbie, E. K.
“Shear-SANS Study of Single-Walled Carbon Nanotube Suspensions ”, Chem. Phys. Lett, 416, 182 (2005). PDF
Hobbie, E. K.,
Bauer, B. J., Stephens, J., Becker, M., McGuiggan, P.,
“Colloidal Particles Coated and Stabilized by
DNA-wrapped Carbon Nanotubes”, Langmuir, 21, 10284 (2005). PDF
Fry, D., Langhorst, B., Kim, H., Grulke, E., Wang,
H., Hobbie, E. K.
“Anisotropy of Sheared Carbon Nanotube Suspensions”, Phys. Rev. Lett., 95, 038304 (2005). PDF
Wang, H., Zhou, W., Ho, D. L., Winey, K. I., Fischer, J. E., Glinka, C. J., Hobbie, E. K.
“Dispersing Single-Wall Carbon Nanotubes with Surfactants: A Small Angle Neutron Scattering Study”, Nano Letters, 4, 1789 (2004). PDF
Lin-Gibson, S., Pathak, J. A., Grulke, E. A., Wang, H. and Hobbie, E. K.
“Elastic Flow Instability in Polymer-Dispersed Nanotubes”, Phys. Rev. Lett., 92 048302 (2004). PDF
Hobbie, E. K., Lin-Gibson, S., Wang, H. and Kim, H.
“Ubiquity of Domain Patterns in Sheared Viscoelastic Fluids”, Phys. Rev. E., 69, 061503 (2004). PDF
Zhou, W., Islam, M. F., Wang, H.,
Ho, D. L., Yodh, A. G., Winey, K.
“Small Angle Neutron Scattering from Single-Wall Carbon Nanotube Suspensions: Evidence of Isolated Rigid Rods and Rod Networks”, Chem. Phys. Lett, 384, 185 (2004). PDF
Wang, H. and Hobbie, E. K.
“Amphiphobic Carbon Nanotubes as Macroemulsion Surfactant”, Langmuir,
19, 3091 (2003). PDF
Hobbie, E. K., Wang, H., Kim, H. J., Lin-Gibson,
S., Hudson, S. D., Han, C. C. and Grulke, E. A.
“Orientation of Carbon Nanotubes in a Sheared Polymer Melt”,
Physics of Fluids, 15, 1196 (2003). PDF
Hobbie, E. K., Wang, H., Hudson, S. D., Han, C. C.
and Obrzut, J.
“Optical Measurement of Structure and Orientation in Sheared Carbon
Nanoube Suspensions”, Rev. Sci. Instr., 74, 1244 (2003). PDF
Polymer thin films, surfaces and interfaces
Chung, H. J., Wang, H., Composto, R. J., “A Morphology Map Based on Phase Evolution in Polymer Blend Films”, Macromolecules, 39,153 (2006).
Wang, H., Douglas, J. F., Satija, S. K., Composto, R. J. and Han, C. C.
“Early-Stage Compositional Segregation in Polymer Blend Films”, Phys. Rev. E, 67, 061801 (2003). PDF
Shin, K., Wang, H., Satija, S. K., Han, C. C., Josell, D. and Bonevich, J. E.
“Rapid Deformation of Thin Gold Layers in Polymer Matrices”, J. Appl. Phys., 94, 2115 (2003). PDF
Wang, H. and Composto, R. J.
“Wetting and Phase Separation in Polymer Blend Films: Identification
of Four Thickness Regimes with Distinct Morphological Pathways”, Interface
Science, 11, 237 (2003) (invited paper) PDF
Wang, H. and Composto, R. J.
“Kinetics of Surface and Interfacial Fluctuations in Phase Separating
Polymer Blend Film”, Macromolecules, 35, 2799 (2002). PDF
Wang, H., Composto, R. J., Hobbie, E. K., and Han,
C. C.
“Multiple Lateral Length Scales in Phase-Separating Thin Film Polymer
Blends”, Langmuir, 17, 2857 (2001). PDF
Wang, H. and Composto, R. J.
“Thin Film Polymer Blends Undergoing Phase Separation and Wetting:
Identification of Early, Intermediate and Late Stages”, J. Chem.
Phys., 113, 10386 (2000). PDF
Wang, H. and Composto, R. J.
“Understanding Morphology Evolution and Roughening in Phase-separating
Thin Film Polymer Blends”, Europhys. Lett., 50, 622 (2000). PDF
Wang, H. and Composto, R. J.
“Hydrodynamic Flow Driven Wetting in Thin Film Polymer Blends: Growth
Kinetics and Direct Observation of Depletion Layer Morphology”, Phys.
Rev. E, 61, 1659 (2000). PDF
Phase behaviors in polymers
Wang, H., “SANS Study of the Early Stages of Crystallization in Polyethylene Solutions”, Polymer, 47, 4897 (2006). PDF
Wang, H. “Small Angle Scattering Study of Polyethylene Crystallization from Solution”, book chapter in “Lecture Notes in Physics: Progress in Understanding of Polymer Crystallization”, Reiter, G. and Strobl, G., Ed. Springer-Verlag, 2006. (Invited)
Wang, Z. G., Wang, H.,
“Structure and Morphology Development in Poly(ethylene-co-hexene) and Poly(ethylene-co-butylene) Blends due to the Competition between Liquid-Liquid Phase Separation and Crystallization”, Polymer, 46, 2675 (2005). PDF
Das, N. C., Wang, H, Mewis, J. and Moldenaers, P., “Rheology and Microstructure Formation in Immiscible Model Polymer Blends under Steady State and Transient Flows”, Polym. Sci. Part B: Polym. Phys., 43, 3519 (2005).
Wang, H.
“Time-Resolved SANS Study of Polyethylene Crystallization from Solution”, J. Polym. Sci. Part B: Polym. Phys., 42, 3133 (2004). (Invited) PDF
Matsuba, G.,
“The Effect of Phase
Separation on
Matsuba, G.,
“Kinetics of Phase Separation and Crystallization in Poly(Ethylene-Co-Hexene) and Poly(Ethylene-Co-Octene)”, Polymer, 44, 7459 (2003). PDF
Müller, A. J., Arnal, M. L., Spinelli, A. L., Canizales, E., Puig, C. C., Wang, H. and Han C. C.
“Morphology and Crystallization Kinetics of Melt Miscible Polyolefin Blends”, Macromolecular Chem. and Phys., 204, 1497 (2003). PDF
Hobbie, E. K., Jeon, H. S., Wang, H., Kim, H. W. Stout, D., Han, C. C.
“Shear-Induced Structure in Polymer Blends With Viscoelastic Asymmetry”, J. Chem. Phys, 117, 6350 (2002). PDF
Wang, H., Hobbie, E. K., Shimizu, K., Wang, G. Z.
G., Kim, H. D. and Han, C. C.
“Competing Kinetics in Simultaneously Crystallizing and
Phase-separating Polymer Blends”, J. Chem. Phys., 116, 7311
(2002). PDF
Wang, H., Shimizu, K., Hobbie, E. K., Wang, G. Z.
G., Meredith, J. C., Karim, A., Amis, E. J., Hsiao, B. S., Hsieh, E. T. and
Han, C. C.
“Phase Diagram of a Nearly Isorefractive Polyolefin Blend”, Macromolecules,
35, 1072 (2002). PDF
Wang, G. Z. G., Wang, X. H., Hsiao, B. S.,
Phillips, R. A., Medellin-Rodriguez, F. J., Srinivas, S., Wang, H. and Han, C.
C.
“Structure and Morphology Development in Syndiotactic Polypropylene
during Isothermal Crystallization and Subsequent Melting”, J.
Polym. Sci. Part B: Polym. Phys., 39, 2982 (2001).
Biomimetic lipids systems
Wang, H., Nieh, M. P., Hobbie, E. H., Glinka, C. J. and Katsaras, J.
“Kinetic Pathways of the Bilayered-Micelle to Perforated-Lamellae Transition”, Phys. Rev. E., 67, 060902(R) (2003) PDF
Nieh, M. P., Raghunathan, V. A., Wang, H. and Katsaras, J.
“Highly Aligned Lamellar Lipid Domains Induced by Macroscopic Confinement”, Langmuir, 19, 6936 (2003). PDF
Electronic and low-dielectric-constant materials
Lee, H. J., Lin, E. K., Wang, H., Wu, W. L., Chen,
W. and Moyer E. S.
“Structural Comparison of Hydrogen Silsesquioxane Based Porous Low-k
Thin Films Prepared with Varying Process Conditions ”, Chem.
Mater., 14, 1845 (2002). PDF
Bauer, B., Lin, E. K., Lee, H. J., Wang, H. and
Wu, W. L.
“Structure and Property Characterization of Low-k Dielectric Porous
Thin Films”, J. Electronic Materials, 30, 304 (2001).
Lin, E.
K., Lee, H. J., Bauer, B. J., Wang, H., Wetzel, J. T. and Wu, W. L.
“Structure and Property Characterization of Low-k Dielectric
Porous Thin Films Determined by X-ray Reflectivity and Small-angle Scattering”,
in Low Dielectric Constant Materials for IC Applications, Eds. Ho, P.
S., Leu, J. and Lee, W. W., Springer Publishing, (2001).
Jin, S. X., Wang, H. P., Yuan, M. H., Song, H. Z.,
Wang, H., Mao, W. L., Qin, G. G., Ren, Z. Y., Li, B. C., Hu X. W. and Sun G. S.
“Controlling of Schottky-barrier height for Au/N-GaAs an Ti/N-GaAs
with Hydrogen Introduced after Metal-deposition by Bias Annealing”, Appl.
Phys. Lett., 62, 2719 (1993).
Miscellaneous proceedings and preprints
Chen, F., Xue, Y. Y., Stokes, K.
L., Wang, H. and
“Transport Properties for Carbon Nanotubes Under Hydrostatic Pressure”, Proc. NanoTech 2003 (2003).
Nieh, M. P., Raghunathan, V. A., Glinka, C. J., Wang, H. and Katsaras, J.,
“A Metastable Aligned Lamellar Phase, Populated with Defects Lying on a Two-Dimensional Lattice and Induced by Macroscopic Confinement”, Biophys. J., 84, 368A (2003).
Han, C. C, Wang, H., Shimizu, K., Kim, H., Hobbie,
E. K. and Wang, G. Z. G.
“Structure Development from Simultaneous Phase Separation and
Crystallization of Metallocene Polyolefin Blends”, Abstr, Pap. Am.
Chem. S., 224, 761 (2002), invited.
Shimizu, K., Wang, H., Wang, Z. G., Han, C. C.
“Phase Behavior in Polyolefin Blends”, Abstr, Pap. Am.
Chem. S., 224, 207 (2002).
Matsuba, G., Shimizu, K., Wang, H., Wang, Z. G.,
Han, C. C.
“Correlation Between Phase Separation and Crystallization of
Poly(ethylene-co-hexene) and Poly(ethylene-co-octene)”, Abstr,
Pap. Am. Chem. S., 224, 206, (2002).
Wang, Z. G., Wang, H., Hsiao, B. S. Gersappe, D.
and Han, C. C.
“In-situ Samll-Angle X-ray scattering Study of Crystallization in
Poly(ethylene/hexane) Copolymer subjected to Step Shear”, American
Chemical Society, 223rd National Meeting (Orlando, FL, April 2002).
Shimizu, K., Wang, H., Wang, Z.G. and Han, C. C.
“Morphological Development in Copolymer Blends of
Poly(ethylene-co-hexane) and Poly(ethylene-co-butene) ”, American
Chemical Society, 223rd National Meeting (Orlando, FL, April 2002).
Shin, K., Wang, H., Satija, S. K., Han, C. C. and
Josell, D.
“X-ray Reflectivity Study of Gold Nanoparticles in a Polymer
Matrix”, Mat. Res. Sci. Symp. Proc., 710, (2002).
Bauer, B., Lin, E. K., Lee, H. J., Wang, H. and
Wu, W. L.
“Structure and Property Characterization of Low-k Dielectric Porous Thin
Films”, Abstr, Pap. Am. Chem. S., 221,
U297 (2001).
Wang, H.,
Wang, G. Z. G., Han, C. C. and Hsiao, B. S.
“Simultaneous SAXS and WAXS study of the Isothermal
Crystallization in Polyolefin Blends”, Polymeric Materials:
Science & Engineering, Preprint, 85, 427 (2001).
Wang, G. Z. G., Wang, H., Shimizu, K., Han, C. C.
and Hsiao, B. S.
“Early Stage Crystallization in Poly(ethylene-co-hexene) by SAXS/WAXS,
DSC, OM and AFM”, Polymeric Materials: Science &
Engineering, Preprint, 85, 435 (2001).
Wang, H. and Han, C. C.
“Silica Nanoparticle Filled Poly(ethylene-co-hexene)/xylene Gels”,
Mat. Res. Sci. Symp. Proc., 661 (2001).
Wang, H. and Han, C. C.
“Cessation of Spherulitic Growth in Phase-separating Polyolefin Blends”,
Abstr, Pap. Am. Chem. S., 220, U323 (2000).
Lin, E.
K., Lee, H. J., Wang, H. and Wu, W. L.
“Structure and Property Characterization of Low-k Dielectric
Porous Thin Films Determined by X-ray Reflectivity and Small Angle Neutron
Scattering”, Proc. of 2000 Inter. Conf. on Characterization and
Metrology for ULSI Technology (2000).
Tools
|
· Small angle neutron scattering (SANS) · Neutron reflectivity (NR) · Neutron spin echo (NSE) · Small angle X-ray scattering (SAXS) · Wide angle X-ray scattering (WAXS) · X-ray reflectivity (XR) · Forward recoil spectrometry (FRES) |
·
· Atomic force microscopy (AFM) · Laser light scattering (SALS) · Thin film deposition · Microfabrication · Photolithography · Numerical simulations |
|
Polymer Suppliers Scientific Polymer Products,
Inc. |
Optics Hamamatsu |
Software |