March 3 - 5,1999, Karlsruhe, Germany - FZK

understanding the transient nature of the
composition that continually changes during
polymerization where monomer is depleted and the
polymer forms and its molecular weight and the
molecular weight distribution changes. The
question of miscibility therefore needs to be
addressed along the reaction coordinate in view of
the changing nature of the chain length and
microstructure of the polymer and the changing
composition of the medium.
b) Generation of more information on swelling of
polymers (being modified or synthesized) and the
influence of the solvent on the lowering of the glass
transition temperature or the melting/crystallization
temperature of the polymer that forms.
c) Generation of more information on the viscosity of
the reaction mixture during polymerization.
d) Generation of more information on kinetic
parameters related to chemical and physical
aspects, such as polymerization rates and rate of
new phase formation and growth. Already
significant activity is underway at University of
Göttingen that uses pulsed laser polymerization
technique to address these fundamental issues.
e) There will be significant effort to explore new
approaches to better control of molecular weight,
and molecular weight distribution, or chain
sequence distributions. Greater exploitation of
Metallocene catalysis, and adoption of Atom
Transfer Radical Polymerization methodologies
for high pressure and supercritical fluid media are
just two examples. Copolymerizations will be a
major .focus area with emphasis on microstructure
regulation via modulation of reactivity ratios. For
example taking advantage of the differences in
activation volumes has not yet been explored or
exploited in this context.
f) Polymer modification area through in-situ
polymerizations, side group modifications, or
surface modifications via grafting or coatings, is
expected to grow, opening new paths for
producing microstructured composite or hybrid
materials.
g) Polymerization with multifunctional monomers or
in the presence of crosslinking agents to produce
gels and crosslinked systems offer unique
potentials that have not yet been explored to any
significant extent.
h) Depolymerization or reactive schemes for recycling
will continue to be an active area.
i) In terms of fluid medium, majority of the effort will
continue to be in the use of carbon dioxide, alone or
with another solvent. Polymerization in binary fluid
mixtures will be an important area of activity.
13
j) From processing perspective, schemes that
integrates polymerization with post processing
steps (such as recovery of the polymer or polymer
fractions in a target solvent- and / or impurity-free
physical form) will be under intense consideration
to make the processes economically more
attractive.
Literature Citations
Reviews
1. K. M. Scholsky, J. Supercritical Fluids, 6, 103-128,
1993.
2. E. Kiran, in Supercritical Fluids, E. Kiran and J.M.H.
Levelt Sengers, Eds., Kluwer Academic Publishers,
Dordrecht, The Netherlands, 1994; pp. 541-588.
3. D. A. Canelas and J. M. DeSimone, Adv. Polym. Sei.
133, 103-140, 1997.
4. Y. Ogo, JMS-Rev. Macromol. Chem. Phys. C24(l),
1-48, 1984.
5. J. K. Beasley, in Comprehensive Polymer Science, G.
Allen, Ed., Pergamon Press, New York, 1989; pp. 273-
282.
Ethylene polymerization and copolymerization
6. P. Ehrlich and G. A. Mortimer, Adv. Polym. Sei., 7,
386-448, 1970.
7. B. G. Kwag and K. Y. Choi, Ind. Eng. Chem. Res. 33,
211-217, 1994.
8. M. H. Lacunza, P. E. Ugrin and A. Brandolin, Latin
Am. Applied Res., 28, 101-106, 1998.
9. B. J. Folie and M. Radosz. Ind. Eng. Chem. Res. 34,
1501, 1995.
10. D. Huekelbach, and G. Luft, Fluid phase equilibria,
146, 187-195, 1998.
11. J. A. Ewen, Scientific American, May 1997, pp. 86-
91.
12. C. Bergemann and G. Luft. J. Molec. Catalysis A:
Chemical 135, 41-45, 1998.; also C. Bergemann, R.
Copp and G. Luft, J. Molec. Catalysis A: Chemical 102,
1-5, 1995.
Copolymerization of carbon dioxide
13. S. Inoue, H. Koinuma and T. Tsurata. J. Polin. Sei.
Polymer Letters 7, 287, 1969.
14. S. Inoue, Chemtech , 6, 588, 1976
15. D. J. Darensbourg, N. W. Stafford and T. Katsurao,
J. Molecular Catalysis A: Chemical 104, L1-L4, 1995.