Advanced Science,
Год журнала:
2024,
Номер
unknown
Опубликована: Ноя. 18, 2024
Abstract
Plastic
recycling
is
a
critical
step
toward
improving
waste
management
and
achieving
economic
recycling.
Here,
thermoset
crosslinked
by
guanythiourea
structure
(GTUH
network)
reported,
that
addresses
the
issue
of
thermosets
serial
hybridization
thiourea
guanidine
urea.
The
dual
dissociative
dynamic
exchange
reaction
guanamine
urea
thiourea,
combined
with
non‐covalent
hydrogen
bonding
interactions,
endows
network
rapid
relaxation
ability.
GTUH
networks,
in
particular,
can
be
recycled
through
continuous
extrusion
processing
due
to
multiple
reversible
mechanisms,
as
opposed
hot
pressing
alone.
Even
if
reprocessed
pressing,
only
5
min
at
140
°C
10
MPa
are
required.
oxidation
enhancement
mechanism
contributes
maintaining
or
even
mechanical
properties
network.
Moreover,
reactions
allow
for
closed‐loop
chemical
Research
into
recyclable
carbon
fiber‐reinforced
composites
indicates
promising
potential
applications
this
material
circular
economy
resources.
Macromolecules,
Год журнала:
2025,
Номер
58(4), С. 1923 - 1934
Опубликована: Фев. 5, 2025
Developing
closed-loop
recyclable
thermosets
and
understanding
their
structure–property
relationships
are
essential
steps
in
advancing
a
circular
materials
economy.
Here,
we
present
vinylogous
urethane
(VU)
thermoset
with
recyclability,
synthesized
through
the
reaction
of
polytetrahydrofuran
bisacetoacetate
(aPTHF)
tris(2-aminoethyl)amine
(TREN).
These
VU
polymers
exhibit
high
elasticity,
only
3–9%
residual
strain
observed
after
cyclic
tensile
testing
at
maximum
100%,
depending
on
molecular
weight
aPTHF
network
cross-link
density.
The
two
structural
parameters
also
allow
modulation
mechanical
stress-relaxation
properties
elastomers.
To
investigate
hydrolysis
linkages
within
hydrophobic
matrix,
employed
heterogeneous
system
using
biphasic
mixture
HCl
CDCl3.
Our
findings
show
that
VUs
remain
stable
pure
water
but
can
be
dissociated
under
acidic
conditions,
dissociation
rate
accelerated
higher
temperatures
and/or
presence
concentrations.
detailed
investigations
indicate
potential
elastomers
as
sustainable
substrates
for
wearable
sensors.
We
therefore
conduct
case
study
synthesizing
sensor
incorporation
multiwalled
carbon
nanotubes
(MCNs)
into
elastomer
matrix.
robustly
detect
various
movements.
Moreover,
treatment
both
neat
polymer
composite
diethyl
ether
solvent
allows
excellent
recovery
(>90%)
TREN
(86%),
without
discernible
damage
to
MCNs
reclaimed
from
latter.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
unknown
Опубликована: Июнь 3, 2024
Covalent
adaptable
networks
(CANs),
leveraging
the
dynamic
exchange
of
covalent
bonds,
emerge
as
a
promising
material
to
address
challenge
irreversible
cross-linking
in
thermosetting
polymers.
In
this
work,
we
explore
introduction
catalyst-free
and
associative
C=C/C=N
metathesis
reaction
into
polyurethanes,
creating
CANs
with
superior
stability,
solvent
resistance,
thermal/mechanical
properties.
By
incorporating
reaction,
stress-relaxation
is
significantly
accelerated
compared
imine-bond-only
networks,
rate
adjustable
by
modifying
substituents
ortho
position
double
bonds.
The
obtained
plasticity
enables
recycle
without
altering
chemical
structure
or
mechanical
properties,
also
found
be
vital
for
achieving
shape
memory
functions
complex
spatial
structures.
This
new
crosslinker
polymer
has
potential
accelerate
ongoing
exploration
malleable
functional
thermoset
Chemical Communications,
Год журнала:
2024,
Номер
60(75), С. 10354 - 10357
Опубликована: Янв. 1, 2024
The
presence
of
dynamic
covalent
bonds
allows
vitrimers
to
undergo
topology
alterations
and
display
self-healing
properties.
Herein,
we
study
the
influence
varying
concentration
on
macroscopic
properties
hybrid
vitrimer
networks
by
subjecting
them
triaxial
stretching
tests
using
molecular
simulations.
Results
show
that
for
continuous
stress
relaxation
in
leading
delayed
craze
development
higher
as
compared
permanently
crosslinked
networks.
work
highlights
ability
glassy
relax
tensile
during
deformation
successfully.
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
Angewandte Chemie,
Год журнала:
2024,
Номер
unknown
Опубликована: Июнь 3, 2024
Abstract
Covalent
adaptable
networks
(CANs),
leveraging
the
dynamic
exchange
of
covalent
bonds,
emerge
as
a
promising
material
to
address
challenge
irreversible
cross‐linking
in
thermosetting
polymers.
In
this
work,
we
explore
introduction
catalyst‐free
and
associative
C=C/C=N
metathesis
reaction
into
polyurethanes,
creating
CANs
with
superior
stability,
solvent
resistance,
thermal/mechanical
properties.
By
incorporating
reaction,
stress‐relaxation
is
significantly
accelerated
compared
imine‐bond‐only
networks,
rate
adjustable
by
modifying
substituents
ortho
position
double
bonds.
The
obtained
plasticity
enables
recycle
without
altering
chemical
structure
or
mechanical
properties,
also
found
be
vital
for
achieving
shape
memory
functions
complex
spatial
structures.
This
new
crosslinker
polymer
has
potential
accelerate
ongoing
exploration
malleable
functional
thermoset
