Research Interests
Solution, diffusion and permeation. Separation membranes.
Electronic and electrochemical membranes. Degradation and
other environmental effects on polymers. Mechanical
properties, deformation and fatigue of polymers.
Multicomponent polymer systems. Adhesion and adhesives,
sealants and coatings. Surface science and technology.
Overview of Research
Research studies are focused on three major areas of
polymer science and technology. These may be designated as
Diffusion, Deformation and Degradation. Diffusion studies
are concerned with transport (permeation and diffusion) and
solution of low molecular weight materials (gases, vapors,
liquids and ions) in and through polymeric materials.
Dependence of those processes on polymer composition,
structure and morphology relative to the physiochemical
nature of the penetrant materials is determined to elucidate
mechanisms of transport and sorption processes and as a
means to probe molecular details of polymer structure and
morphology. Studies proceed on both experimental and
theoretical levels, seeking to relate observed mass
transport behavior and other measures of structure and
dynamics of polymeric materials, such as NMR imaging (NMRI)
and positron annihilation (PAL) spectroscopies, to free
volume and other concepts of segmental dynamics in polymeric
systems. Technical applications are as protective barrier
materials (adhesives, coatings, and packaging films),
permselective separation membranes, electrochemical
membranes (battery separator membranes, polymeric fuel cell
electrolytes) and for assessment of environmental agent
attack on polymeric materials in general. Deformation
studies include the wide range of mechanical (e.g., tensile,
dynamic mechanical, etc.) and viscoelastic (stress
relaxation, creep, etc.) properties that are used to
characterize polymeric materials, especially under end-use
environmental exposure conditions. Emphasis has been on
fracture and mechanical fatique processes in the presence of
aggressive environmental agents (e.g., plasticization,
environmental stress cracking, etc.). These studies employ a
number of investigative techniques (e.g., optical microscopy
and birefringence, TEM and SEM, PIXE, AFM, UV, FTIR, NMR,
etc.) to further establish relationships between observed
properties and polymer characteristics. Degradation studies
include effects of thermal-oxidative, photo-oxidative and
chemical reagent-induced degradations under systematic
variations of environmental exposure conditions, usually
involving controlled static or cyclic mechanical
deformations of polymeric materials. Effects of these
degradation processes are investigated by the techniques
listed above and by determination of relevant mechanical,
viscoelastic and other physical properties, including
penetrant transport and solution parameters. Interdependence
of these three areas of polymer science and technology is of
particular interest. Studies include the six binary
combinations (e.g., effects of deformation on diffusion,
effects of diffusion on deformation, effects of deformation
on degradation, etc.) and the concurrent interdependence of
all three on physiochemical characteristics of system
components and properties and on their performance behavior
under end-use conditions for a wide variety of applications.
The studies proceed both by experimental determinations,
using custom designed and built transport apparatus
complimented by a wide range of modern polymer
characterization techniques, and by theoretical studies
employing statistical thermodynamic methods and computer
modeling. These studies, including synthesis and
characterization of unique polymer membrane materials for
barrier, permselective and electrochemical applications,
often are carried out in cooperation with various faculty
colleagues.
Current Activity
The concurrence of diffusion and stress relaxation
processes, as they vary with temperature, applied mechanical
stress and polymer composition/structure, has been
elucidated by studies of sorption, diffusion, creep, stress
relaxation, stress-strain behavior, positron annihilation
spectroscopy, optical birefringence and other techniques.
The combined processes follow a general functional
dependence on the detailed spectrum of relaxation times
characterizing the polymer-penetrant systems. A statistical
mechanical relationship to describe and predict this
behavior is being developed. Mathematical representations
for the kinetics of consecutive second-order reactions are
being developed. Literature data for certain reactions and
experimental data for selected inorganic reactions are being
employed to guide the derivations and to test the validity
and applications of the derived expressions. It is intended
to apply the work to more complex organic reactions
including those involving polymers. A study of the effects
of nanometric dimension fillers on free volume, relaxation
and transport processes is focused on the nature of the
surface composition and structure of the filler as it
affects the interphase properties of adsorbed polymers of
various controlled compositions. Depending on the strength
of the interfacial interaction, and perhaps other factors,
it seems that free volume may either increase or decrease in
the interphase regions with consequent specific effects on
relaxation and transport behavior.
Selected Publications
Rogers, C. E., “Permeation of Gases and Vapours in
Polymers”, in Polymer Permeability, Chap. 2, Comyn, J., ed.,
Elsevier Appl. Sci. Publ., London, 1985.
Tonyali, K., Rogers, C. E. and Brown, H. R.,
“Stress-Cracking of High-Density Polyethylene in
Detergents”, Polym. Engr. Sci., 27, 82 (1987).
Rogers, C. E., “Effects of Environmental Exposure on
Sorption and Transport of Penetrants in Polymeric
Materials”, Polym. Sci. Tech., 37, 31 (1988).
Rogers, C. E. and Shen, Z.-H., “Formation of Porous
membranes by Mechanical Deformation” U.S. Patent 4,762,657
(Aug. 9, 1988).
Yang, T. and Rogers, C. E., "Selective Permeation of a
Gas Mixture in Surface-Modified PMMA/PVDF Polyblend
Membranes", AIChE Symp. Ser, 85, 11 (1989).
Zhang, T., Litt, M. H. and Rogers, C. E.,
“Sulfone-Containing Polymers as High Barrier Materials”, J.
Polym. Sci., Part B: Polym. Phys., 32, 1671 (1994).
Higuchi, H., Yu, Z., Rogers, C. E., Simha, R., and
McGervey, J. D., "Gas Diffusion Properties and Free Volume",
Polym. Prepr. (ACS, Div. Polym. Chem.), 36(2), 57 (1995).
Lee, J.-C., Litt, M. H. and Rogers, C. E., “Oxyalkylene
Polymers with Alkylsulfonylmethyl Side Chains: Gas Barrier
Properties”, J. Polym. Sci., Part B: Polym. Phys., 36, 75
(1998).
Awards
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