Controlled Radical Polymerization of Myrcene in Bulk:
Mapping the Effect of Conditions on the System
Nicole Bauer
Jessica Brunke
Gergely Kali
10.1021/acssuschemeng.7b02091.s001
https://acs.figshare.com/articles/journal_contribution/Controlled_Radical_Polymerization_of_Myrcene_in_Bulk_Mapping_the_Effect_of_Conditions_on_the_System/5449948
Solvent-free reversible
deactivation radical polymerization of
myrcene, a naturally occurring terpenoid monomer, with high regioselectivity
was developed recently. Here, this green polymerization system is
further improved to reach increased yields and produce polymers with
high molar mass but still low dispersity and regioregular microstructure.
To this end, two initiators (dibenzoyl peroxide, DBPO; azobis(isobutyronitrile),
AIBN) at 65, 90, and 130 °C were applied, and it was demonstrated
that these varying conditions have a huge effect not only on the monomer
conversion and the molar mass of the product, but also on the microstructure
of the resulting polymyrcene. The polymerizations utilized two trithiocarbonate
chain-transfer agents, and were similar in yields, molar masses, and
dispersity of the produced polymyrcene, but progressed differently
for the diverse initiator–temperature pairs. Generally, in
all systems, pseudo-first-order kinetics, linear increase of molar
mass with conversion, and low <i>Đ</i> values were
found as a result of controlled polymerization. The systems using
AIBN and DBPO initiators at 90 and 130 °C, respectively, have
rate constants of propagation (<i>k</i><sub>p</sub><sup>app</sup>) lower than the decomposition
rates (<i>k</i><sub>d</sub>) of initiators, likewise important
to control the polymerizations. At 130 °C, also branching occurred
at the higher stage of the reaction, and lower regioregularity developed
during the polymerization as a consequence of the favorable junction
formation at elevated temperature and increased viscosity. Generally,
compared to the previous study on the reversible deactivation radical
polymerization of myrcene via reversible addition–fragmentation
chain-transfer polymerization process, significantly higher conversions
(30 → 65%) and increased chain length (9 → 40 kDa) were
reached. The dispersity values for these polymerizations remained
as low as 1.3–1.6, and also regioregular microstructures (up
to 94%) were detected.
2017-09-14 00:00:00
molar mass
Controlled Radical Polymerization
k p app
polymerization
AIBN
DBPO
initiator