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.

   

Publications

 

(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., Hudson, S. D., Wang, H.

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. I. and Fischer, J. E.

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., Shimizu, K., Matsuba, G., Hsiao, B. S., Dong, J. Y. and Han, C. C. 

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

 

Shimizu, K., Wang, H., Wang, Z. G. Matsuba, G., Kim, H. and Han, C. C.  Crystallization and Phase Separation Kinetics in Blends of Linear Low-Density Polyethylene Copolymers”, Polymer, 45, 7061 (2004). PDF

 

Matsuba, G., Shimizu, K., Wang, H., Wang, Z. G. and Han, C. C.

The Effect of Phase Separation on Crystal Nucleation Density and Lamella Growth in Near-Critical Polyolefin Blends”, Polymer, 45, 5137 (2004). PDF

 

Matsuba, G., Shimizu, K., Wang, H., Wang, Z. G. and Han, C. C.

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 Chu, C. W.

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)

·        Rutherford backscattering spectrometry (RBS)

·        Atomic force microscopy (AFM)

·        Laser light scattering (SALS)

·        Thin film deposition

·        Microfabrication

·        Photolithography

·        Numerical simulations

 

Related Links

 

Polymer Resources

IRC in Polymer Science and Technology at the University of Leeds
Polymer Chemistry Hyperlink
Macrogalleria
Polymers and Liquid Crystals at CWRU
HC Technologies – Polymer World
NIST Polymers Division
Polymers at the University of Akron
Polymers at the University of Massachusetts, Amherst
Solvent Database from NCMS

Polymer Journals

Macromolecules
Polymer
Journal of Chemical Physics
Journal of Physical Chemistry
Journal of Polymer Science – Part B, Polymer Physics
Langmuir
Physical Review Letters
Physical Review E
Europhysics Letter


 

Societies

American Physical SocietyDivision of Polymer Physics
American Chemical SocietyDivision of Polymer Chemistry
Materials Research Society
Neutron Scattering Society of America
American Institute of Chemical Engineers
Society of Plastic Engineers
Society of Rheology

Plastic Companies

BASF
Dow Chemical
Dow Corning
DuPont
Exxon-Mobil
General Electric Plastics
Plastics.com

 

Instruments

Digital Instruments
Headways
Lakeshore
Keithley
Mettler
National Instruments
Omega
Parker Hannifin
Scientific Solutions

J. A. Woollam
Spincoater
Benchtop-Ultrasonics
Samco
Jelight Company
WITec GmbH
Zatkoff
Perkin-Elmers

Materials

Alfa Aesar
Avanti Lipids
Cambridge Isotope
CDN Isotope
EM Industries
Sigma-Aldrich
Goodfellow
Gelest
Fisher Scientific

 

Polymer Suppliers

Scientific Polymer Products, Inc.
Polymer Source, Inc.
PolySciences, Inc
Polymer Laboratories
Pressure Chemical

Optics

Hamamatsu
Melles Griot
Newport
Roper Scientific
Farfield Sensors
Edmund
Nikon

Software

Genplot and Rump
Igor Pro
Origin
Scion Image