Polymers,
Journal Year:
2024,
Volume and Issue:
16(10), P. 1373 - 1373
Published: May 11, 2024
Covalent
adaptable
networks
and
vitrimers
are
novel
polymers
with
dynamic
reversible
bond
exchange
reactions
for
crosslinks,
enabling
them
to
modulate
their
properties
between
those
of
thermoplastics
thermosets.
They
have
been
gathering
interest
as
materials
recycling
self-healing
properties.
In
this
review,
we
discuss
different
molecular
simulation
efforts
that
used
over
the
last
decade
investigate
understand
nanoscale
behaviors
covalent
vitrimers.
particular,
dynamics,
Monte
Carlo,
a
hybrid
dynamics
Carlo
approaches
model
reaction,
which
is
main
mechanism
since
it
controls
both
mechanical
rheological
behaviors.
The
techniques
presented
yield
sufficient
results
structure
well
responses
such
networks.
benefits
each
method
highlighted.
use
other
tools
theoretical
models
machine
learning
has
included.
We
noticed,
amongst
most
prominent
results,
stress
relaxes
reaction
happens,
at
temperatures
higher
than
glass
transition
temperature,
better
more
BERs
observed.
lifetime
crosslinks
follows,
moderate
high
temperatures,
an
Arrhenius-like
temperature
dependence.
note
modeling
certain
like
melt
viscosity
topology
freezing
according
behavior
ruled
by
either
Williams–Landel–Ferry
equation
or
Arrhenius
equation.
Discrepancies
in
dissociative
associative
discussed.
conclude
stating
material
parameters
atomistic
factors,
nanoscale,
not
yet
taken
into
account
lacking
current
literature.
Macromolecules,
Journal Year:
2024,
Volume and Issue:
57(15), P. 7112 - 7122
Published: July 30, 2024
Continued
progress
in
understanding
the
relaxations
and
mechanical
performance
of
covalent
adaptable
networks
(CANs)
will
lead
to
further
adoption
these
unique
materials
across
a
wide
range
applications.
Using
model
CAN
system
consisting
dynamic,
aromatic
disulfides
epoxy-amine
thermosets,
several
network
characteristics
were
found
vary
as
function
disulfide
concentration
topological
placement.
The
mass
density
was
increase
significantly
with
concentration,
while
glass
transition
temperature
decreased
linearly
content
(from
190
130
°C),
measured
by
modulated
differential
scanning
calorimetry
dynamic
analysis.
Furthermore,
apparent
activation
energy
transition,
Eg,
estimated
time–temperature
superposition,
increasing
concentration.
Significant
changes
sub-Tg
also
observed
correlate
strongly
placement
bonds
within
network.
ACS Macro Letters,
Journal Year:
2025,
Volume and Issue:
unknown, P. 687 - 694
Published: May 12, 2025
The
impact
of
curing
conditions
on
the
final
properties
thioester-thiol-based
dynamic
polymer
networks
was
systematically
investigated.
Despite
identical
monomer
and
cross-linker
compositions,
synthesized
in
absence
solvent
exhibited
significantly
higher
shear
moduli
longer
relaxation
times
compared
to
those
cured
solvent.
These
differences
arise
from
viscosity-controlled
photoinitiated
thiol-ene
reactions,
where
reduced
chain
mobility
under
solvent-free
suppresses
termination
between
two
radicals,
leading
reaction
conversion.
Fourier
Transform
Infrared
(FTIR)
spectroscopy
solid-state
NMR
(ssNMR)
confirmed
a
greater
degree
"click"
completion
viscosity
environments.
Control
experiments
revealed
that
prolonged
radical
lifetimes
suppressed
reactions
contribute
these
variations.
This
study
highlights
crucial
role
processing
determining
cross-link
density
and,
consequently,
mechanical
behavior
networks.
It
demonstrates
that,
beyond
chemistry,
design,
phase
separation,
serve
as
key
design
parameter
for
tailoring
material
performance
specific
applications.
Macromolecules,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Nov. 26, 2024
Vitrimers,
as
a
novel
class
of
dynamic
polymers,
require
precise
regulation
their
and
mechanical
properties
to
achieve
optimal,
comprehensive
performance.
This
study
utilizes
coarse-grained
vitrimer
elastomer
model,
composed
simple
linear
polymer
chains
by
varying
cross-link
densities
(ρ),
systematically
investigate
the
structural,
dynamic,
vitrimers.
The
results
demonstrate
that
system
number
density
decreases
with
increasing
ρ
due
repulsion
between
reactive
sites.
characteristic
glass
transition
temperature
(Tg)
increases
linearly
such
Tg
∼
ρ,
while
topological
Tv
exhibits
nonmonotonic
changes
versus
ρ.
Interestingly,
bond
exchange
autocorrelation
function
indicates
rate
reaches
maximum
at
intermediate
attributed
competition
mobility
Mean
square
displacement
analysis
reveals
beads
decreased
logarithm
diffusion
coefficients
ln
D
−ρ.
chain
segment
relaxation
times
different
can
be
described
an
exponential
equation
τα
exp(ρ/C),
whole
are
more
sensitive
density.
viscoelasticity
via
equilibrium
molecular
dynamics
simulations
indicate
higher
lead
greater
elasticity
energy
dissipation
capabilities,
indicated
storage
loss
moduli,
derived
viscosity
for
various
barriers
(ΔEsw)
universal
following
relation
η0
Uniaxial
triaxial
tensile
tests
both
show
high
ΔEsw
systems
exhibit
strength
low
strains
tight
stable
network
structure,
whereas
strains,
voids
occur
stress
concentration
breakage
covalent
bonds,
which
reduces
strength,
toughness,
elongation
break,
compared
lower
systems.
Therefore,
optimal
tailoring
barrier
capability
most
excellent
performance
vitrimer.
These
findings
provide
crucial
theoretical
guidelines
design
optimization
