JACS Au,
Год журнала:
2024,
Номер
4(8), С. 3058 - 3069
Опубликована: Июль 12, 2024
The
cross-linked
structures
of
most
commodity
polyurethanes
(PUs)
hinder
their
recycling
by
common
mechanical/chemical
approaches.
Catalyzed
dynamic
carbamate
exchange
emerges
as
a
promising
PU
strategy,
which
converts
traditional
static
thermosets
into
reprocessable
covalent
adaptable
networks
(CANs).
However,
this
approach
has
been
limited
to
thermoset-to-thermoset
reprocessing
CANs,
accompanied
well-preserved
network
and
extremely
high
viscosities,
pose
challenges
processing
certain
applications.
This
study
reports
catalytic
decross-linking
extrusion
process
aided
small-molecule
carbamates,
can
upcycle
easily
processable
functional
thermoplastics
in
solvent-free
high-throughput
manner.
Key
is
the
employment
carbamates
decross-linkers
simultaneously
deconstruct
PUs
functionalize
decross-linked
chains,
through
catalyzed
reactions
twin-screw
extruder.
strategy
applies
both
aromatic
aliphatic
films
foams,
amount
required
decross-link
determined
thermal,
chemical,
structural
analyses
resulting
extrudates.
generalizable
with
various
steric/electronic
chemical
functionalities
including
methacrylate,
anthracene,
stilbene
groups.
chain-end
functionalization
confirmed
analyzing
purified
extrudates
after
dialysis.
thermoset-to-thermoplastic
represents
powerful
for
upcycling
postconsumer
library
thermoplastic
controlled
molecular
weights
diverse
applications,
adhesives,
photoresins,
stimuli-responsive
materials,
demonstrated
herein.
In
future,
could
be
extended
many
other
step-growth
capable
undergoing
bond
reactions,
such
polyureas
polyesters,
contributing
plastic
waste
management
general.
Chemical Reviews,
Год журнала:
2024,
Номер
124(16), С. 9609 - 9632
Опубликована: Июль 25, 2024
Recycling
mixed
polyolefin
plastics
is
a
significant
challenge
due
to
the
limitations
in
sorting
and
degraded
mechanical
properties
of
blends.
Nonreactive
compatibilization
by
adding
small
amount
polymeric
additive
widespread
approach
restoring
performance
value
recycled
plastics.
Over
past
several
decades,
synthetic
advances
have
enabled
access
low-cost
copolymers
precision
architectures
for
deepening
understanding
mechanisms
semicrystalline
polyolefins.
This
review
covers
design
parameters
compatibilizer,
testing
blends,
methods
producing
economically
viable
additives,
surveys
literature
blends
compatibilized
HDPE,
LLDPE,
LDPE,
iPP.
From
this,
readers
should
gain
comprehension
polymer
mechanics,
synthesis,
macromolecular
engineering
processable
along
with
field's
future
directions.
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
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(23), С. 16257 - 16267
Опубликована: Июнь 4, 2024
The
spontaneous
condensation
of
amines
with
β-triketones
(TK),
forming
β,β′-diketoenamines
(DKE)
and
releasing
water
as
the
sole
byproduct,
exhibits
many
hallmarks
"click"
reactions.
Such
characteristics
render
TKs
a
highly
advantageous
platform
for
efficient
polymer
diversification,
even
in
biological
contexts.
Leveraging
reversible
addition–fragmentation
chain
transfer
(RAFT)
photoiniferter
polymerization
novel
TK-containing
vinylic
monomers,
we
synthesized
polymers
containing
pendent
excellent
control
molecular
weights,
excess
106
g
mol–1.
Under
mild,
catalyst-free
conditions,
poly(β-triketone
methacrylate)
could
be
modified
diverse
scope
plethora
functional
groups.
high
efficiency
this
functionalization
approach
was
further
emphasized
when
grafting-to
poly(ethylene
glycol)-amine
resulting
bottlebrushes
weights
reaching
2.0
×
107
Critically,
while
formed
DKE
linkages
are
stable
under
ambient
they
undergo
catalyst-free,
dynamic
transamination
at
elevated
temperatures,
paving
way
associative
covalent
adaptable
networks.
Overall,
introduce
triketone
moieties
into
methacrylate
acrylamide
polymers,
establishing
postpolymerization
modification
technique
that
facilitates
ligation
permissible
conditions.
Giant,
Год журнала:
2024,
Номер
19, С. 100307 - 100307
Опубликована: Июнь 14, 2024
Polyolefins
are
the
most
produced
and
widely
used
polymeric
materials.
However,
chemically
inert
nature
of
polyolefins
has
led
to
severe
environmental
pollution,
posing
a
threat
human
sustenance
development.
Managing
recycling
polyolefin
plastic
waste
is
crucial
for
transition
from
linear
sustainable
circular
economy.
Catalytic
chemical
includes
traditional
techniques
like
pyrolysis
photolysis,
innovative
methods
that
introduce
cleavable
bonds
into
chain
closed-loop
recycling.
post-functionalization
post-consumer
materials
another
strategy
tackle
waste,
aiming
upgrade
materials'
utility
contribute
sustainability.
Overall,
developing
catalytic
deconstructing
upcycling
plastics
essential
encourage
better
reclamation
practices
reduce
impact
waste.
ACS Applied Polymer Materials,
Год журнала:
2024,
Номер
unknown
Опубликована: Дек. 3, 2024
Polyolefins
like
polyethylene
(PE)
and
ethylene-based
copolymers
are
widely
used
in
consumer
industrial
applications
due
to
their
versatility,
the
diversity
tunability
of
properties,
theoretical
recyclability
at
elevated
temperatures.
However,
recycling
rates
markedly
low,
and,
though
cross-linking
PE
enhances
its
properties
through
creation
a
networked
architecture,
resulting
thermoset
known
as
PEX
is
rendered
completely
unrecyclable.
Incorporating
associative
or
dissociative
dynamic
covalent
bonds
cross-links
into
plastics
promising
route
both
make
use
spent
(via
"upcycling"
them)
generate
recyclable
alternatives
unrecyclable
thermosets
PEX.
Such
materials
adaptable
networks
CANs
(also
called
vitrimers
if
exclusively
associative).
Here,
we
present
method
for
imbuing
polymers
with
aromatic
disulfide
cross-links,
robust,
reprocessable
CANs.
Radical-based
reactive
processing
ethylene/1-octene-based
1
wt
%
dicumyl
peroxide
5
bis(4-methacryloyloxyphenyl)
(BiPheS
methacrylate
BPMA)
successfully
resulted
which
fully
recovered
cross-link
densities
associated
thermomechanical
after
multiple
reprocessing
cycles.
These
demonstrate
remarkable
elevated-temperature
creep
resistance
high-temperature
thermal
stability
high
temperatures
required
exchanges
BiPheS-based
cross-links.
copolymer
also
enable
(re)processability
via
extrusion
temperatures,
property
recovery
demonstrated
260
°C,
thereby
indicating
feasibility
extending
our
approach
scales
processes
well
other
rigorous
applications.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(44)
Опубликована: Авг. 6, 2024
Abstract
The
development
of
mechanically
robust,
chemically
stable,
and
yet
recyclable
polymers
represents
an
essential
undertaking
in
the
context
advancing
a
circular
economy
for
plastics.
Here,
we
introduce
novel
cleavable
β‐(1,3‐dioxane)ester
(
DXE
)
linkage,
synthesized
through
catalyst‐free
reaction
β‐ketoester
1,3‐diol,
to
cross‐link
poly(vinyl
alcohol)
PVA
formation
high‐performance
thermosets
with
inherent
chemical
recyclability.
,
modified
groups
transesterification
excess
tert
‐butyl
acetoacetate,
undergoes
cross‐linking
reactions
unmodified
1,3‐diols
within
itself
upon
thermal
treatment.
architecture
improves
’s
mechanical
properties,
Young's
modulus
toughness
that
can
reach
up
656
MPa
84
MJ
cm
−3
i.e.
approximately
3‐
12‐fold
those
linear
respectively.
Thermal
treatment
cross‐linked
under
acid
conditions
leads
deconstruction
networks,
enabling
excellent
recovery
(>90
%)
.
In
absence
either
or
acidic
treatment,
maintains
its
dimensional
stability.
We
show
is
also
possible
when
performed
presence
other
plastics
commonly
found
recycling
mixtures.
Furthermore,
‐based
composites
comprising
carbon
fibers
activated
charcoal
by
linkages
are
shown
be
fillers.
Advanced Functional Materials,
Год журнала:
2024,
Номер
unknown
Опубликована: Окт. 6, 2024
Abstract
Vitrimers
are
promising
next‐generation
materials,
often
exhibiting
superior
properties
such
as
mechanical
strength
and
solvent
resistance
compared
to
their
thermoplastic
counterparts,
while
still
featuring
recyclability
due
dynamic
covalent
crosslinks.
The
most
common
strategy
recycle
vitrimers
is
via
reprocessing
at
high
temperatures,
others
utilize
chemical
degradation
reobtain
the
constituent
monomers.
This
work
presents
a
new
approach
toward
by
selectively
breaking
of
vitrimer's
crosslinks,
turning
it
back
into
thermoplastic.
allows
for
be
achieved
in
more
sustainable
manner
lower
temperatures
shorter
times.
After
desired
shape
has
been
obtained,
facile
re‐crosslinking
turns
material
vitrimer,
with
full
restoration
thermal
stability,
properties,
gel
fraction.
To
achieve
this,
carbene
C─H
insertion
utilized
introduce
an
imine‐based
crosslinker
various
thermoplastics
plastic
mixtures
convert
them
vitrimers.
Properties
typical
retained
polymer
network
Arrhenius‐type
relationship
between
stress
relaxation
rate
temperature
observed,
its
elongation
break
tensile
toughness,
particularly
significantly
enhanced,
first
crosslinking,
then
further
enhanced
up
8
folds
reversible
crosslinking
process.
