Bio


Do Y. Yoon is Adjunct Professor of Chemical Engineering at Stanford University since 2012. He obtained his B.S. in Chemical Engineering from Seoul National University, South Korea (1969), and earned his Ph.D. in Polymer Science and Engineering from University of Massachusetts Amherst, working with Richard S. Stein (1973). He did his postdoctoral study with Paul J. Flory in Chemistry Department of Stanford University (1973-1975). He then worked in IBM Research Laboratory in San Jose, California as Research Staff Member and Manager of Polymer Physics Group (1975-1999). From 1999 to 2012, he was Professor of Chemistry at Seoul National University, South Korea. He was also visiting professor at Max Planck Institute for Polymer Research (2000–2006), National Institute of Standards and Technology (2006–2012), and University of Bayreuth (2012). He published about 250 research papers, was elected a fellow of American Physical Society in 1985, and received a Senior Humboldt Research Award in 1999. His research areas include molecular conformations & dynamics, semicrystalline morphology, liquid crystalline order, surface and thin film characteristics of polymers, and structure-property relationships of polymers for information technology and clean energy. He is a co-editor of "Selected Works of Paul J. Flory" and a co-author of "Paul John Flory: A Life of Science and Friends."

Academic Appointments


2017-18 Courses


All Publications


  • Interfacial and topological effects on the glass transition in free-standing polystyrene films JOURNAL OF CHEMICAL PHYSICS Lyulin, A. V., Balabaev, N. K., Baljon, A. R., Mendoza, G., Frank, C. W., Yoon, D. Y. 2017; 146 (20)

    Abstract

    United-atom molecular-dynamics computer simulations of atactic polystyrene (PS) were performed for the bulk and free-standing films of 2 nm-20 nm thickness, for both linear and cyclic polymers comprised of 80 monomers. Simulated volumetric glass-transition temperatures (Tg) show a strong dependence on the film thickness below 10 nm. The glass-transition temperature of linear PS is 13% lower than that of the bulk for 2.5 nm-thick films, as compared to less than 1% lower for 20 nm films. Our studies reveal that the fraction of the chain-end groups is larger in the interfacial layer with its outermost region approximately 1 nm below the surface than it is in the bulk. The enhanced population of the end groups is expected to result in a more mobile interfacial layer and the consequent dependence of Tg on the film thickness. In addition, the simulations show an enrichment of backbone aliphatic carbons and concomitant deficit of phenyl aromatic carbons in the interfacial film layer. This deficit would weaken the strong phenyl-phenyl aromatic (π-π) interactions and, hence, lead to a lower film-averaged Tg in thin films, as compared to the bulk sample. To investigate the relative importance of the two possible mechanisms (increased chain ends at the surface or weakened π-π interactions in the interfacial region), the data for linear PS are compared with those for cyclic PS. For the cyclic PS, the reduction of the glass-transition temperature is also significant in thin films, albeit not as much as for linear PS. Moreover, the deficit of phenyl carbons in the film interface is comparable to that observed for linear PS. Therefore, chain-end effects alone cannot explain the observed pronounced Tg dependence on the thickness of thin PS films; the weakened phenyl-phenyl interactions in the interfacial region seems to be an important cause as well.

    View details for DOI 10.1063/1.4977042

    View details for Web of Science ID 000401778900016

    View details for PubMedID 28571360

  • Interface characteristics of polystyrene melts in free-standing thin films and on graphite surface from molecular dynamics simulations POLYMER Lee, S., Lyulin, A. V., Frank, C. W., Yoon, D. Y. 2017; 116: 540-548
  • Temperature dependence of surface reorganization characteristics of amphiphilic block copolymer in air and in water studied by scanning force microscopy JOURNAL OF PLASTIC FILM & SHEETING Lee, S., Flores, S. M., Berger, R., Gutmann, J. S., Brehmer, M., Conrad, L., Funk, L., Theato, P., Yoon, D. Y. 2015; 31 (4): 434-448
  • Organosilicate polymer e-beam resists with high resolution, sensitivity and stability APPLIED ORGANOMETALLIC CHEMISTRY Lee, S., Sim, J. H., Lee, H., Kasica, R., Kim, H., Soles, C. L., Kim, K., Yoon, D. Y. 2013; 27 (11): 644-651

    View details for DOI 10.1002/aoc.2985

    View details for Web of Science ID 000326332800006

  • Concentration Dependence of Ring Polymer Conformations from Monte Carlo Simulations ACS MACRO LETTERS Reigh, S. Y., Yoon, D. Y. 2013; 2 (4): 296-300

    View details for DOI 10.1021/mz300587v

    View details for Web of Science ID 000317813200004

  • Surface reorganization of an amphiphilic block copolymer film studied by NEXAFS spectroscopy MACROMOLECULES Theato, P., Brehmer, M., Conrad, L., Frank, C. W., Funk, L., Yoon, D. Y., Luning, J. 2006; 39 (7): 2592-2595

    View details for DOI 10.1021/ma0509964

    View details for Web of Science ID 000236574400026

  • Correlation of surface and bulk order in low surface energy polymers MACROMOLECULES Luning, J., Stohr, J., Song, K. Y., Hawker, C. J., Iodice, P., Nguyen, C. V., Yoon, D. Y. 2001; 34 (5): 1128-1130

    View details for DOI 10.1021/ma0001584

    View details for Web of Science ID 000167136000002

  • Dynamic light scattering studies of cholesteric and polymer-stabilized cholesteric liquid crystals PHYSICAL REVIEW E Borsali, R., Schroeder, U. P., Yoon, D. Y., Pecora, R. 1998; 58 (3): R2717-R2720
  • Determination of splay and twist relaxation modes in nematic liquid crystals from dynamic light scattering experiments JOURNAL OF PHYSICAL CHEMISTRY B Borsali, R., Yoon, D. Y., Pecora, R. 1998; 102 (33): 6337-6341
  • THE INTERPHASE IN LAMELLAR SEMICRYSTALLINE POLYMERS MACROMOLECULES FLORY, P. J., Yoon, D. Y., DILL, K. A. 1984; 17 (4): 862-868
  • AMORPHOUS POLYMERS - GENERAL DISCUSSION FARADAY DISCUSSIONS DILL, K. A., Frank, F. C., SADLER, D. M., DIMARZIO, E. A., GUTTMAN, C. M., Hoffman, J. D., FLORY, P. J., Yoon, D. Y., Dowell, F., Stein, R. S., SAMULSKI, E. T., Windle, A. H., EVERETT, D. H., Rigby, D., STEPTO, R. F., Pechhold, W., FISCHER, E. W., Lovell, R., Mitchell, G. R., ATKINS, E. D., Mandelkern, L., Keller, A., WARD, I. M., UHLMANN, D. R., Champion, J. V., Waring, R., Thomas, E. L., VESELY, D., GRUBB, D. T., FRANK, W. F., Blundell, D. J., Stamm, M., VANDERSANDE, J. B., Stevens, G. C. 1979; 68: 104-?
  • MOLECULAR MORPHOLOGY IN SEMI-CRYSTALLINE POLYMERS NATURE FLORY, P. J., Yoon, D. Y. 1978; 272 (5650): 226-229
  • ANALYSIS OF NUCLEAR MAGNETIC-RESONANCE SPECTRA OF PROTONS IN PREDOMINANTLY ISOTACTIC POLYSTYRENE MACROMOLECULES Yoon, D. Y., FLORY, P. J. 1977; 10 (3): 562-566
  • PERSISTENCE VECTORS FOR POLYPROPYLENE, POLYSTYRENE, AND POLY(METHYL METHACRYLATE) CHAINS JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS Yoon, D. Y., FLORY, P. J. 1976; 14 (8): 1425-1431
  • SMALL-ANGLE NEUTRON AND X-RAY-SCATTERING BY POLY(METHYL METHACRYLATE) CHAINS .2. MACROMOLECULES Yoon, D. Y., FLORY, P. J. 1976; 9 (2): 299-303
  • SMALL-ANGLE X-RAY AND NEUTRON-SCATTERING BY POLYMETHYLENE, POLYOXYETHYLENE, AND POLYSTYRENE CHAINS MACROMOLECULES Yoon, D. Y., FLORY, P. J. 1976; 9 (2): 294-299
  • SMALL-ANGLE NEUTRON AND X-RAY-SCATTERING BY POLY(METHYL METHACRYLATE) CHAINS POLYMER Yoon, D. Y., FLORY, P. J. 1975; 16 (9): 645-648
  • CONFORMATIONAL CHARACTERISTICS OF POLY(METHYL ACRYLATE) MACROMOLECULES Yoon, D. Y., Suter, U. W., Sundararajan, P. R., FLORY, P. J. 1975; 8 (6): 784-789
  • CONFORMATIONAL CHARACTERISTICS OF POLYSTYRENE MACROMOLECULES Yoon, D. Y., Sundararajan, P. R., FLORY, P. J. 1975; 8 (6): 776-783
  • MOMENTS AND DISTRIBUTION FUNCTIONS FOR POLYMER-CHAINS OF FINITE LENGTH .2. POLYMETHYLENE CHAINS JOURNAL OF CHEMICAL PHYSICS Yoon, D. Y., FLORY, P. J. 1974; 61 (12): 5366-5380
  • MOMENTS AND DISTRIBUTION FUNCTIONS FOR POLYMER-CHAINS OF FINITE LENGTH .1. THEORY JOURNAL OF CHEMICAL PHYSICS FLORY, P. J., Yoon, D. Y. 1974; 61 (12): 5358-5365