Andrew J. Lovinger
DMR Division of Materials Research
MPS Directorate for Mathematical & Physical Sciences
Start Date:
June 1, 2005
Expires:
May 31, 2009 (Estimated)
Awarded Amount to Date:
$400000
Investigator(s):
Ali Dhinojwala alid@polymer.uakron.edu (Principal Investigator)
Sponsor:
University of Akron
302 Buchtel Common
Akron, OH 44325 330/972-7666
NSF Program(s):
POLYMERS
Field Application(s):
0106000 Materials Research
Program Reference Code(s):
AMPP, 9161
Program Element Code(s):
1773
ABSTRACT
We propose to combine surface sensitive infrared-visible sum frequency generation
spectroscopy (SFG) with insitu friction and adhesion measurements. The experiments
are motivated by results of Chaudhury and Brown using poly (dimethylsiloxane) (PDMS)
lenses and Israelachvili using surface force apparatus; where they find a relationship
between friction, adhesion hysteresis and mobility of the molecules at the interface.
However, there is no information on how different relaxation processes are at
polymer/solid or hidden interfaces in comparison to that in bulk. Recent experiments of
glass transition temperature of polymer thin films indicate that the relaxation at the air
interface can be several orders of magnitude faster than in the bulk. The relaxation
times of polymer chains are expected to be altered in contact with surfaces of different
surface energies. Furthermore, there is no direct information of the change in the
structure of molecules at moving or sliding interfaces. Understanding these properties is
crucial to understand friction. Recently, we demonstrated that SFG can be applied to
study the contact interface between an elastomeric PDMS lens and a polymer or solid
substrate. Here, we take advantage of this design to measure simultaneously the
changes in structure between two sliding surfaces, friction and adhesion. In addition, we
propose to measure the relaxation dynamics at interfaces using SFG to understand the
relationship between mobility and friction coefficient. As a Director of District 5, I have
been actively involved in organizing District 5 Science Day for students from K5-K12 for
the past five years. In addition to this outreach activity, this proposal offers research
opportunities to two high school students from a local high school to work during
summer in my laboratory under the supervision of graduate students. The research of
these high school projects can be submitted as a part of their science project for
competition in the Intel Science and Engineering Fair. This effort will be integrated with
the NSF-REU undergraduate program already existing at The University of Akron.
Broader Impact: Friction between two surfaces is of utmost importance in a variety of
technological and biological applications. The understanding and control of these
phenomena will have a tremendous impact in conserving and using precious energy
resources. The advances in this field are limited by the lack of understanding of the
structure and properties of molecules at the interface. This proposal provides a new
experimental method to probe molecular motion or deformation taking place at the
interface and studies its relationship to friction and adhesion. This will broadly impact
our design of surfaces, lubricants and micro or nano-actuators. The education and
outreach activities target local schools in District 5 to promote an interest in science by
encouraging students to undertake science projects and compete at district, state and
international level.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
(Showing: 1 - 11 of 11).
Betul Yurdumakan, Gary P. Harp, Mesfin Tsige and Ali Dhinojwala.
"Template-Induced Enhanced Ordering under Confinement,"
Langmuir,
v.21,
2005,
p. 10316.
Betul Yurdumakan, Kumar Nanjundiah, and Ali Dhinojwala.
"Origin of Higher Friction for Elastomers Sliding on Glassy Polymers,"
Journal of Physical Chemistry C,
v.111,
2007,
p. 960.
Betul Yurdumakan, Nachiket Raravikar, Pulickel Ajayan and Ali Dhinojwala.
"Synthetic Gecko Foot-Hairs from Multiwalled Carbon Nanotubes,"
Chemical Communications,
2005,
p. 3799.
Gary P. Harp and Ali Dhinojwala.
"Direct Probe of Interfacial Structure during Mechanical Contact between Two Polymer Films Using Infrared Visible Sum Frequency Generation Spectroscopy,"
Journal of Adhesion,
v.81,
2005,
p. 371.
Gary P. Harp, Hasnain Rangwalla, Guifeng Li, Mohsen S. Yeganeh, and Ali Dhinojwala.
"Coupling of Interfacial Motion at Polystyrene-Alkane Interfaces,"
Macromolecules,
v.39,
2006,
p. 7464.
Ge, L; Sethi, S; Ci, L; Ajayan, PM; Dhinojwala, A.
"Carbon nanotube-based synthetic gecko tapes,"
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA,
v.104,
2007,
p. 10792
- 10795.
Kumar Nanjundiah and Ali Dhinojwala.
"Confinement-Induced Ordering of Alkanes between an Elastomer and a Solid Surface,"
Physical Review Letters,
v.95,
2005,
p. 154301.
Shishir Prasad and Ali Dhinojwala.
"Rupture of a Two-Dimensional Alkane Crystal,"
Physical Review Letters,
v.95,
2005,
p. 117801.
Shishir Prasad, Laurie Hanne and Ali Dhinojwala.
"Thermodynamic Study of a Novel Surface Ordered Phase above the Bulk Melting Temperature in Alkyl Side Chain Acrylate Polymers,"
Macromolecules,
v.38,
2005,
p. 2541.
Shishir Prasad, Laurie Hanne, and Ali Dhinojwala.
"Surface segregation in polymer blends driven by surface freezing,"
Macromolecules,
v.39,
2006,
p. 7467.
(Showing: 1 - 11 of 11).
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