Dilip Gersappe

PROFESSIONAL INTERESTS

Statistical mechanical and computer modeling of complex chemical systems. Investigating the behavior of self-assembling polymeric and biopolymeric systems. Developing theories for the properties of polymer blends and the behavior of polymers at surfaces and interfaces.

CURRENT POSITION

Assistant Professor, Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook NY 11794

EDUCATION

Ph.D. (1992): Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60201. Thesis title: Statistics and Dynamics of Polymers in Topologically Restricted Environments. Advisor: Prof. Monica Olvera de la Cruz.

B.Tech. (1983-1987) Department of Metallurgical Engineering, Indian Institute of Technology, Bombay.

INDUSTRIAL EXPERIENCE

Consultant: Mitsubishi Chemical Corporation, Production Technology and Engineering Center, Mizushima Plant, 3-10, Ushidori, Kurashiki, Okayama 712, Japan.

RESEARCH EXPERIENCE

Postdoctoral Research: (1996-Oct '97) The following is a list of research projects that I am currently working on at Johns Hopkins University

• Develop parallel code for molecular dynamics to study the properties of thin films undergoing shear. With the use of efficient parallel code we will be able to study large system sizes to determine the molecular response of thin films to external shear forces.
  
• Study the failure mechanisms associated with adhesive polymer layers. Isolate the factors that control the onset of adhesive failure in polymer films.

Postdoctoral Research: (October 92 - 96) The following is a list of research projects I was involved with as a Postdoctoral Research Associate at the University of Pittsburgh. The numbers in parentheses indicate the appropriate paper in the list of publications.

• Determined the effect of molecular architecture on the compatibilizing activities of copolymer chains. In particular, we isolated the effects of copolymer shape and sequence distribution on the efficiency of compatibilizers. Our results showed that, in general, diblock copolymers form better compatibilizers than comb and random copolymers of the same chemical composition [1, 2, 4, 6,12].
  

• Developed computer simulations to study the onset of micellar formation in comb copolymers. Through a series of simulations we were able to isolate the effects of comb architecture on the morphology of the aggregates formed [5].
  
• Studied the formation of lateral structures in grafted copolymer layers through Monte Carlo simulations and Self-Consistent field methods. Our results show that the lateral properties of the adlayer can be controlled through such variables such as chain length and grafting density. Our studies provide guidelines for the fabrication of coatings or films that yield enhanced adhesive, lubricating or wetting properties [1, 3, 7, 11].
  
• Coupled Monte Carlo computer simulations and experimental studies to design comb copolymers that act as "molecular velcro". Here, the teeth intertwine across the interface between two immiscible polymers and reduce the interfacial tension. Our findings show that comb compatibilizers dramatically improve the mechanical properties of polymer blends [8, 9].
  
• Used self-consistent field methods and Monte Carlo simulations to design a polymer channel that could be made to open and close in response to changes in the pH of the solvent. Our studies provide a theoretical framework for understanding the mechanism by which polymers can act as pH-dependent "valves" with potential applications in drug delivery systems [10].
  
• Investigated how the chemical sequence distribution affects the conformation of a copolymer at a bilayer interface. Our results can be used to tailor copolymers that will provide optimal properties at interfaces. Our model can also be used to study interactions between protein molecules and membrane bilayers in order to understand the mechanics of channel formation in cell membranes [14, 15].

Graduate Research: (`87 - `92). This is a list of projects that I was involved with as a Graduate Research Assistant in the Department of Materials Science and Engineering at Northwestern University.

• Developed a new Monte Carlo algorithm to study the statistics of ring macromolecules in disordered systems. Our algorithm proved to be a considerable improvement over previous models. We found that the ring started behaving like a branched polymer as the concentration of the network was increased (corresponding to a decrease in pore size), and formulated a scaling relationship to account for this behavior [13, 16].
  
• Investigated the statistics of a polymer chain in a randomly cross-linked gel through computer simulations. Even when the pore size of the gel was relatively large, the density distribution of the polymer inside the gel showed unusual properties. We were able to characterize this behavior as being multifractal in nature, a phenomenon which was observed for the first time in this polymeric system [17].
  
• Studied the process of gel electrophoresis of linear DNA using Brownian dynamics. From our results, we determined the migration mechanism of the DNA molecule undergoing electrophoresis and isolated parameters to optimize the technique. Our results provided new insights into the diffusive behavior of DNA molecules [18, 19].

TEACHING EXPERIENCE

Teaching Assistant, Statistical Mechanics (1990, 1991, Northwestern University). Helped develop computer assignments for a graduate level course in the department of Materials Science and Engineering.

Teaching Assistant, Computer Methods in Materials Science (1990, Northwestern University). A course designed to introduce seniors and graduate students to the applications of modeling techniques in Materials Science.

Teaching Assistant, Principles of the Properties of Materials (1989, 1990, Northwestern University). An introductory course for undergraduate students majoring in materials science.

PUBLICATIONS

1. "A Jumping Micelle Phase Transition", C. Singh, E. B. Zhulina, D. Gersappe, G.T. Pickett and A. C. Balazs (submitted to Macromolecules).

2. "Designing Optimal Compatibilizers for Reducing Interfacial Tension in Polymer Blends", Y. Lyatskaya, D. Gersappe, N. A. Gross and A. C. Balazs, Journal of Physical Chemistry 100, 1449 (1996).

3. "Tailoring the Structure of Polymer Brushes through Copolymer Architecture", D. Gersappe, M. Fasolka, R. Israels and A. C. Balazs, in Polymer/Inorganic Interfaces II, L. Drzal, R. Oplia, N. Peppas and C. Schutte Eds., Materials Research Society, Pittsburgh, in press.

4. "Random Copolymers as Effective Compatibilizing Agents", D. Gersappe and A. C. Balazs Physical Review E 52, 5061 (1995).

5. "Computer Modeling of Amphiphilic Comb Copolymers in Solution", D. Irvine, D. Gersappe and A.C. Balazs, Langmuir 11, 3848 (1995).

6. "The Effect of Copolymer Architecture on the Efficiency of Compatibilizers", Y. Lyatskaya, D. Gersappe and A. C. Balazs, Macromolecules 28, 6278 (1995).

7. "Modeling the Behavior of Random Copolymer Brushes", D. Gersappe, R. Israels, M. Fasolka and A. C. Balazs, Macromolecules 28, 4753 (1995).

8. "Using Monte Carlo Simulations and Self-Consistent Field Theory to Design Interfacially Active Copolymers", A. C. Balazs, D. Gersappe, R. Israels and M. Fasolka, Macromol. Theory Simul. 4, 585 (1995).

9. "The Use of Graft Copolymers to Bind Immiscible Blends", D. Gersappe, D. Irvine, A. C. Balazs, L. Guo, M. Rafailovich, J. Sokolov, S. Schwarz and D. Peiffer, Science 265, 1073 (1994).

10. "pH-Controlled Gating in Polymer Brushes", R. Israels, D. Gersappe, M. Fasolka, A. C. Balazs and V. A. Roberts, Macromolecules 27, 6679 (1994).

11. "Aggregation in Grafted Polymers with Attractive End-Groups", D. Gersappe, M. Fasolka, A.C. Balazs and S. H. Jacobson, Journal of Chemical Physics 100, 1970 (1994).

12. "Contrasting the Compatibilizing Activity of Comb and Linear Copolymers", D. Gersappe, P.K. Harm, D. Irvine and A.C. Balazs, Macromolecules 27, 720 (1994).

13. "Monte Carlo Studies of Ring Polymers in Disordered Systems", D. Gersappe and M. Olvera de la Cruz, Molecular Simulations 13, 267 (1994).

14. "Computational Studies of Copolymer Adsorption at Bilayer Interfaces", D. Gersappe, W. Li and A. C. Balazs, Journal of Chemical Physics 99, 7209 (1993).

15. "A Theoretical Model for Copolymer-Bilayer Interactions", W. Li, D. Gersappe and A. C. Balazs, Journal of Chemical Physics 99, 4168 (1993).

16. "Ring Macromolecules in Topologically Restricted Environments", D. Gersappe and M. Olvera de la Cruz, Physical Review Letters 70, 461 (1993).

17. "Density Fluctuations of Self-Avoiding Walks in Random Systems", D. Gersappe, J. M. Deutsch and M. Olvera de la Cruz, Physical Review Letters 66, 731 (1991).

18. "Dynamics of Gel Electrophoresis", D. Gersappe and M. Olvera de la Cruz in Computer Simulations of Polymers, Ed. R.J.Roe; Prentice Hall, p. 198 (1991).

19. "Dynamics of DNA during Pulsed Field Gel Electrophoresis", M.Olvera de la Cruz, D. Gersappe and E.O. Shaffer, Physical Review Letters 25, 2324 (1990).

PRESENTATIONS

1. "Using Computer Models to Design Interfacially Active Polymers", April 30th 1996, Dept. of Materials Science and Engineering and Dept. of Chemistry, State University of New York, StonyBrook, NY. (invited talk)

2. "Polymer Adsoprtion on Soft, Responsive Surfaces", APS March Meeting, 1996, St. Louis, MI. (talk)

3. "Tailoring the Structure of Grafted Copolymer Layers", ICAM IV `95, Cancun, Mexico. (invited talk)

4. "Random Copolymers as Effective Compatibilizing Agents", APS March Meeting `95, San Jose, CA. (talk)

5. "The Use of Graft Copolymers to Bind Immiscible Blends", MRS Fall Meeting `94, Boston, MA. (talk)

6. "Using Graft Copolymers to Bind Immiscible Blends", ACS Colloids and Surface Science Meeting `94, Stanford, CA. (talk)

7. "Aggregation in Grafted Polymers with Attractive End-Groups", ACS Colloids and Surface Science Meeting `94, Stanford, CA. (talk)

8. "Aggregation in Polymer Brushes", ANTEC `94, Society of Plastic Engineers Meeting, San Francisco, CA. (talk)

9. "Computational Studies of Copolymer Adsorption at Bilayer Interfaces", ACS Meeting, 1993, Chicago, IL. (talk)

10. "Statistics of Ring Polymers in Disordered Media", APS March meeting,1992, Indianapolis, IN. (talk)

11. "Dynamics of Pulsed Field Gel Electrophoresis", The International Electrophoresis Society Meeting, March 1991, Washington D.C. (invited talk)

12. "Density Fluctuations of Self-Avoiding walks in Random Systems", APS March meeting,1990, Anaheim, CA. (talk)

For more detailed information.....

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