Advanced Materials,
Journal Year:
2024,
Volume and Issue:
36(47)
Published: Oct. 6, 2024
Abstract
Dynamic
covalent
polymer
networks
exhibit
a
cross‐linked
structure
like
conventional
thermosets
and
elastomers,
although
their
topology
can
be
reorganized
through
externally
triggered
bond
exchange
reactions.
This
characteristic
enables
unique
combination
of
repairability,
recyclability
dimensional
stability,
crucial
for
sustainable
industrial
economy.
Herein
the
application
photoswitchable
nitrogen
superbase
is
reported
spatially
resolved
reversible
control
over
dynamic
within
thiol‐ene
photopolymer.
By
exposure
to
UV
or
visible
light,
associative
between
thioester
links
thiol
groups
successfully
gained
over,
thereby
macroscopic
mechanical
material
properties,
in
locally
controlled
manner.
Consequently,
resulting
reorganization
global
network
utilize
this
previously
unrealizable
advanced
applications
such
as
resolved,
reshaping
well
micro‐imprinting
multiple
steps.
Finally,
presented
concept
contributes
fundamentally
evolution
polymers
provides
universal
applicability
adaptable
relying
on
base‐catalyzed
mechanism.
Macromolecules,
Journal Year:
2024,
Volume and Issue:
57(2), P. 682 - 690
Published: Jan. 9, 2024
A
strategy
to
efficiently
synthesize
thermally
reprogrammable
but
mechanically
stable
liquid
crystalline
elastomers
(LCEs)
is
reported
by
investigating
the
catalytic
effects
of
para-substituted
phenols
on
dynamic
aza-Michael
reactions.
The
synthesis
LCEs
was
optimized
based
a
study
catalyzed
small-molecule
reactions,
where
presence
an
electron-withdrawing
substituent
significantly
improved
reactivity
system.
catalysts
were
then
screened
their
exchange
adducts.
Catalysts
with
substituents
efficient
in
inducing
bonds,
thus
influencing
mesogen
alignment
and
actuation.
After
programming
alignment,
catalyst
washed
away
dramatically
reduce
activity
improve
creep
resistance
material
while
preserving
postsynthetic
alignment.
This
approach
represents
straightforward
accessible
methodology
for
obtaining
programmable
as
well
actuators
from
LCEs.
Journal of the American Chemical Society,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Feb. 14, 2025
Thermosets
are
valued
for
their
exceptional
dimensional
stability,
mechanical
properties,
and
resistance
to
creep
chemicals.
Their
permanent
molecular
structures
limit
reshaping,
reprocessing,
recycling.
Incorporating
exchangeable
chemical
bonds
into
cross-linked
polymer
networks
provides
materials
with
thermoset-like
properties
that
also
reprocessable.
Here,
ring-opening
copolymerization
(ROCOP)
of
unpurified,
commercially
available
epoxides
succinic
anhydride
is
employed
synthesize
well-defined,
low
weight
polyesters
controlled
functionalization.
Polymer
then
formed
through
the
catalyzed
reaction
these
copolymers
epoxy-containing
cross-linker
diglycidyl
ether
bisphenol
A.
Catalyst
mixtures
zinc
bis(2-ethylhexanoate)
1,8-diazabicyclo(5.4.0)undec-7-ene
used
assess
role
catalysts
in
curing
dynamic
bond
exchange
reactions.
Varying
catalyst
ratios
results
tunable
(90%
<
εb
450%,
0.30
MPa
UTS
24
MPa),
high
recovery
(%recovery
>
90%
after
five
cycles),
good
reprocessability.
ACS Applied Polymer Materials,
Journal Year:
2024,
Volume and Issue:
6(13), P. 7918 - 7925
Published: June 29, 2024
With
an
ever-increasing
annual
production
of
polymers
and
the
accumulation
polymer
waste
leading
to
progressively
adverse
environmental
consequences,
it
has
become
important
that
all
can
be
efficiently
recycled
at
end
their
life
cycle.
Especially
thermosets
are
intrinsically
difficult
recycle
because
permanent
covalent
cross-links.
A
possible
solution
is
switch
from
using
adaptable
networks,
sparking
rapid
development
novel
dynamic
chemistries
derived
materials.
Next
these
innovative
materials,
there
also
evident
advantage
merging
virtues
networks
with
proven
material
properties
widely
used
commodity
plastics,
by
introducing
bonds
in
original
thermoplastic
materials
obtain
recyclable
thermosets.
Here
we
report
synthesis
characterization
a
polystyrene
polymer,
functionalized
TetraAzaADamantanes
cross-linked
boronic
esters.
The
were
characterized
for
different
degrees
cross-linking.
showed
good
solvent
resistance
high
remaining
insoluble
fraction.
In
line
typical
behavior
traditional
prepared
polystyrene-based
boronate-TetraAzaADamantane
able
undergo
stress
relaxation.
relaxation
was
shown
tunable
mixing
acid
catalyst.
Lastly,
could
least
2
times.
Journal of Polymer Science,
Journal Year:
2024,
Volume and Issue:
62(15), P. 3562 - 3583
Published: May 22, 2024
Abstract
Innovations
in
dynamic
polymeric
materials
offer
prospects
to
improve
the
circularity
and
lower
environmental
impact
of
modern
polymer
economy.
These
are
also
beginning
blur
distinction
between
re‐use
recycling
methods
since
bulk
material
properties
may
be
rationally
changed
after
applying
a
stimulus
or
performing
controlled
chemical
reaction.
In
this
Perspective,
we
propose
that
polymers
denote
unique
class
versatile
post‐consumer
waste,
which
shares
similarities
emergent
upcycling
approaches
while
offering
additional
opportunities
within
more
classical
schemes.
A
brief
overview
stimuli‐responsive
is
presented
where
illustrative
examples
discussed
context
developing
practical
materials.
Dynamic
covalent
then
highlighted,
along
with
emerging
techniques
such
as
editing,
focus
on
recent
reports
demonstrating
rational
manipulation
properties.
Finally,
discuss
these
alongside
explore
how
could
perform
sphere.
Macromolecules,
Journal Year:
2024,
Volume and Issue:
57(14), P. 6759 - 6768
Published: June 28, 2024
Carbamate
formation
and
exchange
catalysts
enable
efficient
polyurethane
(PU)
manufacturing,
as
well
emerging
recycling
reprocessing
methods
for
PU
thermosets.
Zirconium
β-diketonate
complexes,
such
Zr
acetylacetonate
[Zr(acac)4],
are
effective
alternatives
to
toxic
organotin
that
have
been
used
reprocessing.
Here,
we
report
Zr(acac)4
undergoes
a
thermally
activated
process
in
the
network
during
transforms
it
into
more
active
carbamate
catalyst.
This
is
associated
with
irreversible
loss
of
ligands
not
observed
sterically
hindered
2,2,6,6-tetramethyl-3,5-heptanedione
[Zr(tmhd)4]
complex.
Crossover
experiments
between
thermoplastics
indicated
enhanced
after
thermal
activation
presence
one
PUs,
whereas
sample
absence
had
no
catalytic
activity.
Thermal
gravimetric
analysis
suggested
this
protonated
acac
ligand.
Stress
relaxation
thermosets
distinct
change
characteristic
time
at
temperatures
above
140
°C;
was
samples
reprocessed
using
Zr(tmhd)4.
Density
functional
theory
molecular
suggest
ligand
alkoxide
or
reduces
energy
urethane
reversion.
Furthermore,
catalyst
PU's
polyol
precursor
provided
porous
less
dense
foams
compared
those
made
unactivated
These
findings
important
developing
improved
synthesis
processes.
Thermally
activating
may
provide
nuanced
control
in-use
characteristics
Macromolecules,
Journal Year:
2024,
Volume and Issue:
57(17), P. 8277 - 8286
Published: Aug. 23, 2024
Vitrimers
are
permanent
polymer
networks
with
dynamic
covalent
bonds
that
allow
them
to
be
reshaped
and
recycled.
Although
they
often
promoted
as
an
ideal
class
of
materials
situated
between
thermosets
thermoplastics,
vitrimers
usually
far
more
difficult
process
than
thermoplastics
because
their
melt
viscosity
gradually
decreases
increasing
temperature.
They
thus
subject
a
challenging
trade-off
processability
mechanical
performance,
limiting
practical
utility.
Herein,
we
report
the
concept
supramolecularly
masked
cross-linker
enables
vitrimer
precursor
processed
thermoplastic
before
being
thermally
cured
form
vitrimer.
The
features
hydrogen
bonding
groups
promote
aggregation
phase
separation,
allowing
for
it
melt-blended
functional
at
low
temperature
minimal
cross-linking.
After
shaping,
loaded
is
heated
suitably
high
curing
disassemble
aggregated
cross-linker,
thereby
unmasking
reacting
functionalized
matrix.
resulting
elastomeric
exhibit
excellent
thermomechanical
properties
along
chemical
recyclability.
latter
consists
recovering
precursor,
which
can
further
reprocessed
converted
back
after
processing.
