Dynamic
covalent
adaptive
networks
can
solve
the
recycling
issue
of
thermosets.
However,
dissociative
dynamic
may
suffer
from
instability
and
network
incompleteness
at
high
temperatures
or
in
solvents.
Here,
we
report
a
novel
bond,
N-sulfonyl
guanidine
urea
(SGUA),
that
undergo
catalyst-free
metathesis
reactions,
which
passivation
strategy
increasing
dissociation
temperature
by
introducing
electron-withdrawing
groups
into
adjacent
positions
was
developed.
Unlike
conventional
bonds,
SGUAs
exhibit
associative
reactions
around
120–180
°C,
with
threshold
180
°C.
The
polyurea
constructed
SGUAs,
named
PSGUAs,
exhibits
ultrastrong
(Young's
modulus
exceeding
4
GPa
tensile
strength
60
MPa)
stable
(thermal
stability,
structure
integrity
under
reprocessing,
dimensional
stability)
performances.
Furthermore,
due
to
excellent
characteristics
PSGUAs
were
successfully
reprocessed
after
30–60
min
hot
pressing
160
°C
20
MPa.
Combining
long-lasting
antibacterial
properties
long-term
use,
this
study
marks
substantial
improvement
field
polymer
networks,
giving
solution
for
balancing
material
performance,
reprocessability.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(31)
Опубликована: Май 20, 2024
Dithioacetals
are
heavily
used
in
organic,
material
and
medical
chemistries,
exhibit
huge
potential
to
synthesize
degradable
or
recyclable
polymers.
However,
the
current
synthetic
approaches
of
dithioacetals
polydithioacetals
overwhelmingly
dependent
on
external
catalysts
organic
solvents.
Herein,
we
disclose
a
catalyst-
solvent-free
acetal-thiol
click-like
reaction
for
synthesizing
polydithioacetals.
High
conversion,
higher
than
acid
catalytic
reaction,
can
be
achieved.
universality
was
confirmed
by
monitoring
reactions
linear
cyclic
acetals
(including
renewable
bio-sourced
furan-acetal)
with
aliphatic
aromatic
thiols,
mechanism
monomolecular
nucleophilic
substitution
(S
ACS Applied Polymer Materials,
Год журнала:
2024,
Номер
6(15), С. 9209 - 9218
Опубликована: Июль 22, 2024
Aromatic
disulfides
have
seen
widespread
use
in
covalent
adaptable
networks
(CANs),
though
previous
studies
exclusively
used
step-growth
methods
to
integrate
them
into
CANs.
Here,
we
describe
a
case
which
an
aromatic
disulfide-based
cross-linker,
bis(4-methacryloyloxyphenyl)
disulfide,
also
called
BiPheS
methacrylate
or
BPMA,
is
incorporated
CAN
by
nonstep-growth
polymerization.
Free-radical
copolymerization
of
n-hexyl
with
5
mol
%
BPMA
results
exhibits
full
recovery
cross-link
density
and
thermomechanical
properties
across
multiple
reprocessing
cycles.
The
rubbery-plateau
storage
modulus
directly
proportional
absolute
temperature,
characteristic
constant
density,
even
at
temperatures
where
the
reprocessable.
Indeed,
BPMA-based
thus
associative
dynamic
character,
up
least
200
°C,
enabling
it
be
elevated-temperature
applications
without
risk
loss
network
character.
Under
3.0
kPa
shear
stress,
almost
total
arrest
creep
180
°C
major
suppression
its
temperature
overcoming
potential
Achilles'
heel
associated
Thus,
integration
CANs
free-radical
polymerization
provides
facile
route
produce
recyclable
that
maintain
character
very
high
contributing
polymer
sustainability.
Finally,
determined
Arrhenius
apparent
activation
energy
∼100
kJ/mol
for
stress
relaxation
viscosity.
This
value
differs
substantially
from
bond
dissociation
but
agrees
alpha-relaxation
poly(n-hexyl
methacrylate)
(PHMA).
indicates
dependence
these
viscoelastic
responses
our
associative-type
defined
cooperative
segmental
mobility
PHMA,
makes
95
CAN.
ACS Sustainable Chemistry & Engineering,
Год журнала:
2024,
Номер
12(32), С. 12161 - 12170
Опубликована: Авг. 1, 2024
Nonisocyanate
polyurethanes
(NIPUs)
show
promise
as
more
sustainable
alternatives
to
conventional
isocyanate-based
(PUs).
In
this
study,
polyhydroxyurethane
(PHU)
and
nonisocyanate
polythiourethane
(NIPTU)
production
reprocessing
models
inform
the
results
of
a
techno-economic
analysis
life
cycle
assessment.
The
profitability
selling
PHU
NIPTU
is
rationalized
by
identifying
significant
costs,
indicating
that
raw
materials
drive
costs
reprocessing.
After
stepping
along
path
process
improvements,
can
achieve
minimum
prices
(MSPs)
3.15
4.39
USD
kg–1,
respectively.
Depolymerization
yields
need
be
optimized,
polycondensation
reactions
investigated
for
NIPUs
into
secondary
(2°)
NIPUs.
Of
examined
here,
has
low
depolymerization
yield
high
yield.
Fossil
energy
use,
greenhouse
gas
(GHG)
emissions,
water
consumption
are
reported
biobased
PHU,
NIPTU,
2°
compared
with
baseline
values
fossil-based
PU
production.
There
options
reducing
environmental
impacts,
which
could
make
these
pathways
sustainable.
If
barriers
implementation
overcome,
manufactured
at
lower
cost
impacts
than
those
virgin
ACS Macro Letters,
Год журнала:
2024,
Номер
13(9), С. 1147 - 1155
Опубликована: Авг. 16, 2024
We
synthesized
covalent
adaptable
networks
(CANs)
made
from
chain-growth
comonomers
using
nonisocyanate
thiourethane
chemistry.
derivatized
glycidyl
methacrylate
with
cyclic
dithiocarbonate
(GMA-DTC),
did
a
free-radical
polymerization
of
n-hexyl
GMA-DTC
to
obtain
statistical
copolymer
8
mol
%
GMA-DTC,
and
cross-linked
it
difunctional
amine.
The
dynamic
thionourethane
disulfide
bonds
lead
CAN
reprocessability
full
recovery
the
cross-link
density;
temperature
dependence
rubbery
plateau
modulus
indicates
that
associative
character
dominates
response.
exhibits
complete
self-healing
at
110
°C
tensile
property
excellent
creep
resistance
90–100
°C.
Stress
relaxation
140–170
reveals
an
activation
energy
105
±
6
kJ/mol,
equal
(Ea)
poly(n-hexyl
methacrylate)
backbone
α-relaxation.
hypothesize
CANs
exclusively
or
predominantly
dynamics
have
their
stress-relaxation
Ea
defined
by
α-relaxation
Ea.
This
hypothesis
is
supported
stress
studies
on
similar
poly(n-lauryl
methacrylate)-based
CAN.
Journal of Applied Polymer Science,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 31, 2025
ABSTRACT
Phenolic
resin
has
high
heat
resistance
and
excellent
mechanical
properties,
its
cross‐linked
network
structure
shows
properties
after
curing.
However,
it
is
difficult
to
recycle
the
phenolic
because
of
insoluble
infusible
features.
In
order
make
recyclable
reprocessable,
we
introduced
polymethylene
polyphenyl
polyisocyanate
(PAPI)
into
resin,
made
phenol
hydroxyl
group
react
with
isocyanate
form
reversible
dynamic
covalent
bond,
prepared
modified
(PANR).
The
structure,
thermal
stability,
fracture
morphology
reprocessable
PANR
were
characterized.
results
showed
that
when
PAPI
was
NR,
successfully
bonds.
DSC
glass
transition
temperature
as
175°C,
TGA
mass
retention
rate
still
about
40%
at
800°C.
tensile
strength
14.7
MPa,
chemical
remain
more
than
95%
original
five
cycles,
which
realizes
recovery
reprocessing
cured
resin.
expected
be
used
in
