PhD Thesis
Zur anionischen Copolymerisation von 5-( N,N-Dialkylamino)isoprenen
Gerd Mannebach (01/1999-01/1999)
Summary
The incorporation
of amine functions into diene monomers leads to polar monomers which
provide
access to new polymers with a wide range of properties. Within this
work homo-
and copolymers of 5-(N,N-dialkylamino)isoprenes were
prepared in n-hexane and THF. It is shown that side
reactions occur in nonpolar solvents at elevated temperatures, which
prevent
full conversion. A polymerization in THF - initiated with alkyllithium
- is
extremely slow. In contrast to nonpolar solvents it shows first order
kinetics with
respect to the concentration of monomers. In the copolymerization of
5-(N,N-dialkylamino)isoprenes in n-hexane the composition of the
copolymers is
strongly dependent on the steric effects of the alkyl side chains of
the amino
group. For larger differences in the bulkiness of the alkyl side chains
the
structures are more blocklike. During the copolymerization of
5-(N,N-dialkylamino)isoprene with 1,3-butadiene one finds that the
polar
aminoisoprene is incorporated first into the polymer. On varying the
dialkylaminogroup,
copolymers with tapered or blocklike structures are obtained which
contain
different 1,2-contents of butadiene. Kinetic experiments show that the
solubility of the living polymer and the rate of propagation are
dependent on
intra- and intermolecular interactions between the amino functions and
the
living chain ends. The reactivity ratios in the copolymerization with
1,3-butadiene were determined. Rheological experiments indicate an
interaction
of the dialkylamino groups in the polymer melt as well as microphase
separation. Polar modified solution SBRs were synthesized by anionic
terpolymerization of 5-(N,N-dialkylamino)isoprenes with styrene and
1,3-butadiene in n-hexane, with an addition of small amounts of THF. By
comparing the kinetic experiments in the absence and presence of THF an
increase of the rate of propagation is found for the statistical
copolymerization of styrene with 1,3-butadiene. In a cooperation with
BAYER AG
these new polarmodified solution SBRs were investigated in rubber
mixtures and
an enhancement of properties compared to conventional polymers used for
profile
tires was found.