Reactivity of allyl and vinyl pentosides in photo-initiated donor-acceptor copolymerization - Carbohydrate Chemistry: Chemical and Biological Approaches - page 293

25%, the glass transition temperature was about -50 1C, comparable to
that of soft polyurethanes with flexible segments. 73
Tetra-allyl monomer. When TAX was copolymerized with 4 equivalent
of DEF and 1 wt-% of TPO as photo-initiator, almost all fumarate
unsaturations were consumed (p N A = 90%) within 150 minutes of
irradiation, whereas the conversion of allylethers was about 20%. TAX
should then be considered as a crosslinking agent for diethyl fumarate.
As previously noticed, the broad glass transition (spreading over a range
of 80 1C) is typical of the formation of heterogeneous polymer structures.
The T g values increased significantly with the conversion of both como-
nomers. Indeed, after 30 minutes of irradiation, the glass transition
temperature was still low ( 10 1C) but reached 25 1C after 180 minutes of
irradiation (Fig. 7). The materials were clear and colorless, and exhibited
good flexibility.
5 Conclusion
In the present chapter, we have reviewed the production of macro-
molecular materials from allyl and vinyl carbohydrates. On the basis of
the current state-of-the-art achieved in sugar-based polymerization, we
have explored the reactivity of vinyl and allyl ethers borne by glycoside
derivatives for donor-acceptor copolymerization.
The reactivity of vinyloxy and allyloxy monomers derived from polyols
and simple carbohydrates was quantitatively evaluated in free-radical
UV-initiated copolymerization with acceptor monomers such as DEF or
DEM. Kinetic data confirmed the lower reactivity of allylethers compared
with vinyloxy analologs as described in literature. Interestingly, allyl
ribosides exhibited the highest reactivity in the allyloxy series combined
with the highest final conversion levels. A correlation between the donor
monomer structure described by Hansen parameter d H , corresponding to
H-bonding interactions, and the initial polymerization rate has been
established.
Mechanistic investigations of donor-acceptor copolymerization from
allyl and vinyl ethers with simple structure have been achieved by
in-depth characterization of finalcopolymersusingSEC,NMRspec-
troscopy and ESI-MS. Optimal conditions for the synthesis of a rigor-
ously alternating copolymer with high molecular weight were
determined. The importance of transfer reactions competing with
propagation during the copolymerization of allylethers was supported
by ESI-mass spectrometry. Finally, the synthesis of macromolecular
networks with a large renewable carbon content was performed by poly-
merization of model hybrid monomers bearing a donor and an acceptor
function or by copolymerization of a multifunctional donor monomer
both derived from xylose with DEF or DEF. Transparent and soft networks
exhibiting a glass transition temperature between 40 and þ 25 1C were
obtained depending on their composition and degree of curing. The bulk
copolymerization of allyloxy derivatives of carbohydrates with fumarates
is demonstrated as a novel route yielding bio-based networks with ad-
justable properties.