Research Interests
Irreversible microdeformation mechanisms; pressure effects on morphology and mechanical properties; relationships between hierarchical structure and mechanical function; mechanical properties of soft connective tissue; polymer composites and blends; polymerization and crystallization on crystalline surfaces; viscoelastic properties of polymer melts; damage and fracture analysis of polymers and their composites. Structure-property relationships in biological systems.
Overview of Research
Our interests focus on the relationships between hierarchical structure and mechanical function of polymeric materials. Hierarchical structure in biocomposite systems such as in collagenous connective tissue has many scales or levels, and there are highly specific interactions between these levels. We were among the first to demonstrate that the hierarchical architecture is designed to accommodate a complex spectrum of mechanical property requirements. The hierarchical structure-property relationships have been described in several soft connective tissues: tendon, intestine and invertebral disc. Numerous levels of organization are found with highly specific interconnectivity and unique architectures designed to give the required spectrum of properties for each oriented composite system. From these lessons in biology, the laws of complex composite systems for functional macromolecular assemblies are considered.
Current Activity
As Co-director of the NSF Science and Technology Center for Layered Polymeric Systems (CLiPS,) he helps lead the combined the combined technological and educational efforts of researchers at Case Western Reserve (the lead institution), its partners and affiliates .
Recent work involves creation of the world’s smallest polymer continuous micro-coextrusion system which will extend the capabilities of CLiPS enabling nanolayering technology. New micro- and nanolayered systems are being used for fundamental studies of polymer-polymer interphase, nucleation of polymer nanodroplets, crystallization and phase transformation in confined spaces, aging of polymer nanolayers, and interfacial reactions by combining self-assembly with forced-assembly. Analytical models have been created for microlayered systems that interdiffuse and concurrently crystallize.
Additional work has been focused in the area of micromechanics. Interactive models have been developed to explain toughness enhancement as a result of cooperative crazing and shear banding. As a result, new insights have been developed in the area of rubber toughening of amorphous thermoplastics and reinforced layered structures.
Recent Publications
H. Wang, J. K. Keum, A. Hiltner, E. Baer, B. Freeman, A. Rozanski, A. Galeski. Confined Crystallization of Polyethylene Oxide in Nanolayer Assemblies, Science, 2009, 323,757-760.
Puente Orench, N. Stribeck, F. Ania, E. Baer, A. Hiltner, F.J. Baltá Calleja. SAXS Study on the Crystallization of PET under Physical Confinement in PET/PC Multilayered Films Polymer, June 2009, 50 (12), p.2680-2687.
S. Armstrong, Z. Zhou, A. Hiltner, E. Baer. Incorporation of Lead Phthalocyanine into Periodic Nanolayered Assemblies for Advanced Optical Systems J. Appl. Polym. Sci., (2009) 113, 2565-2572.
M. Mackey, A. Hiltner, E. Baer, L. Flandin, M. A. Wolak, J. S. Shirk. Enhanced Breakdown Strength of Multilayered Films Fabricated by Forced Assembly Microlayer Coextrusion J. Phys. D: Appl Phys. (2009) 42, 175304.
M. Gupta, Y. Lin, T. Deans, A. Crosby, E. Baer, A. Hiltner, D. A. Schiraldi. Biaxially-Oriented Poly(Propylene-G-Maleic Anhydride)/Phosphate Glass Composite Films for High Gas Barrier Applications Polymer, 2009, 50, 598-604.
K. Singer, T. Kazmierczak, J. Lott, H. Song, Y. Wu, J. Andrews, E. Baer, A. Hiltner, C. Weder. Toward Roll-to-Roll Production of Polymer Microresonator Lasers Optics and Photonics News, December, 2008 (special edition, Optics in 2008).
R. Masirek, E. Piorkowska, A. Galeski, A. Hiltner, E. Baer. High Pressure Crystallization of HDPE Droplets Macromolecules, 2008, 41, 8086-8094.
V. V. Pethe, H. P. Wang, A. Hiltner, E. Baer, and B. D. Freeman. Oxygen and Carbon Dioxide Permeability of EAA/PEO Blends and Microlayers J. Appl. Polym. Sci., 2008, 110, 1411-1419.
R. Ayyer, A. Hiltner, E. Baer. Effect of an environmental stress cracking agent on the mechanism of fatigue and creep in polyethylene Journal of Materials Science, vol. 43, issue 18, October, 2008, pp. 6238-6253.
G. Beadie, L. M. Sandrock, M. J. Wiggins, R. S. Lepkowicz, J. S. Shirk, M. Ponting, Y. Yang, T. Kazmierczak, A. Hiltner, E. Baer Tunable Polymer Lens Optics Express 2008, 16, 11847-11857.
G. Beadie, J. S. Shirk, A. Rosenberg, P. A. Lane, E. Fleet, A. R. Kamdar, Y. Jin, M. Ponting, Y. Yang, T. Kazmierczak, A. Hiltner, E. Baer Optical properties of a bio-inspired gradient refractive index polymer lensOptics Express, 2008, 16, 11540-11547.
K. Singer, T. Kazmierczak, J. Lott, H. Song, Y. Wu, J. Andrews, E. Baer, A. Hiltner, C. Weder. Melt-processed, All-polymer, Distributed Bragg Reflector Laser Optics Express, 2008, 16, 10358-10363.
F. Ania, I. Orench, F. Balta Calleja, D. Khariwala, A. Hiltner, E. Baer, S. Roth. Ultra-small-angle X-ray Scattering Study of PET/PC Nanolayers Relating to AFM Results Macromol. Chem. Phys., 2008, 209, 1367-1373.
P. Dias, Y. J. Lin, B. Poon, H. Y. Chen, A. Hiltner, E. Baer. Adhesion of statistical and blocky ethylene-octene copolymers to polypropylene Polymer, 2008, 49, 2937-2946.
Y. J. Lin, P. Dias, H. Y. Chen, A. Hiltner, E. Baer. Relationship between biaxial orientation and oxygen permeability of polypropylene film Polymer, vol. 49, issue 10, May 13, 2008, pp. 2578.
W. Cheng, N. Comopoulos, G. Fytas, T. Gorshnyy, J. Walish, E. L. Thomas, A Hiltner, E. Baer. Phonon Dispersion and Nanomechanical Properties of Periodic 1D Multilayer Polymer Films Nanoletters, 2008, 8, 1423-1428.
Y. J. Lin, P. Dias, H. Y. Chen, S. Chum, A. Hiltner, E. Baer. Oxygen permeability of biaxially oriented polypropylene films, with Polymer Science and Engineering, vol. 48, issue 4, April 2008, pp. 642-648.
M. S. Wolak, MJ Pan, A Wan, JS Shirk, M Mackey, A Hiltner, E Baer, L Flandin. Dielectric response of structured multilayered polymer films fabricated by forced assembly Appl. Phys, Lett., 2008, 92, article 113301.
D. Khariwala, A Taha, S Chum, A Hiltner, E Baer. Crystallization kinetics of some new olefinic block copolymers, with Polymer, vol 49, issue 5, March 3, 2008, pp. 1365-1375.
Recent Presentations
“Polymer Nanolayered Graded Index Lenses – Lessons from
Biology,” Naval Research Lab, Washington, D.C., November 16,
2004.
“Polymer Nanolayered Graded Index Lenses – Lessons from
Biology,” Eastman Kodak Company, Rochester, New York,
November 17, 2004.
“Bio-Mimetic GRIN Lens Using Polymeric Nanolayered Film
Systems,” Materials Research Society meeting, Boston,
Massachusetts, November 29 – December 3, 2004.
“Hierarchical Biostructures and Nanolayered Systems,”
Department of Chemical Engineering, Case Western Reserve
University, January 27, 2005.
“Forced Assembly into Polymer Nanolayers: Creating Polymer
Plus,” 28th Asilomar Conference on Polymeric Materials,
Asilomar State Park, Pacific Grove, CA, February 13-16,
2005.
“Creating Polymeric Nanolayered Systems by Forced Assembly,”
Dept. of Polymer Science and Engineering, University of
Massachusetts, April 22, 2005.
“Polymeric Nanolayered Film Systems,” SPE/ANTEC 2005
meeting, Boston, Massachusetts, May 3, 2005.
“Forced Assembly into Polymer Nanolayers: Creating Polymers
Plus,” 10th Symposium on Deformation Mechanisms in Micro-
and Nanostructured Polymers, Martin Luther University, Halle,
Germany, May 19-20, 2005.
“Bio-mimetic GRIN Lenses Ujing Polymeric Nnolayered Film
Systems,” 230th ACS National Meeting, Washington, DC, August
28 – September 1, 2005.
“Solid State Dynamic GRIN Lens,” Bio-Optic Synthetic Systems
Phase II Principal Investigator Conference, Santa Fe, New
Mexico, October 25-57, 2005.
“Bio-mimetic GRIN Lens Using Polymeric Nanolayered Film
Systems,” 3M Company, St. Paul, Minnesota, November 21,
2005.
Awards
2000: Inducted into The Plastics Hall of Fame, June 22,
2000
1999: Roon Foundation Award, Federation of Societies for
Coatings Technology and Coatings Industry Education Fund
1998: Humel Hovorka Prize of CASE
1997: Paul J. Flory Education Award of the ACS
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