A
vitrimer
has
covalent
cross-links
that
preserve
network
connectivity
but
permit
topology
fluctuations
through
dynamic
exchange
reactions.
In
this
work,
we
investigate
the
linear
rheology
of
polybutadiene
(PB)
vitrimers
bearing
via
dioxaborolane
metathesis.
PB
are
cross-linked
in
solution
using
photoinitiated
thiol-ene
click
chemistry.
As
targeted
cross-link
density
is
increased,
both
insoluble
fraction
and
glass
transition
temperature
increase.
Linear
viscoelasticity
studied
a
combination
small
amplitude
oscillatory
shear
(SAOS),
creep,
stress
relaxation
measurements.
SAOS,
elastic
modulus
approximately
constant
while
viscous
increases
as
angular
frequency
decreases.
compliance
displays
power
law
behavior
persists
for
at
least
8
hrs.
relaxation,
transitions
from
rubbery
plateau
into
regime.
Both
SAOS
creep
data
visually
superposed
master
curves
horizontal
shift
factors
exhibit
Arrhenius
behavior.
However,
activation
energies
smaller
than
those
factors.
The
match
effective
Williams-Landel-Ferry
energy
homopolymer,
indicating
short
time
dynamics
correspond
to
strand
segment
relaxations.
contrast,
significantly
larger
predicted
by
established
theoretical
models
transient
networks.
We
speculate
discrepancy
between
experiment
theory
due
dependence
cross-linker
mobility
within
matrix,
which
not
fully
captured
models.
Green Chemistry,
Год журнала:
2024,
Номер
26(12), С. 6857 - 6885
Опубликована: Янв. 1, 2024
Amongst
all
synthetic
polymers
used
in
the
clothing
industry,
polyethylene
terephthalate
(PET)
is
most
widely
polyester,
its
fibres
representing
half
total
PET
global
market
(in
comparison
bottle
being
less
than
a
third).
Macromolecules,
Год журнала:
2023,
Номер
56(17), С. 6806 - 6817
Опубликована: Авг. 16, 2023
A
vitrimer
has
covalent
cross-links
that
preserve
network
connectivity
but
permit
topology
fluctuations
through
dynamic
exchange
reactions.
In
this
work,
we
investigate
the
linear
rheology
of
polybutadiene
(PB)
vitrimers
bearing
via
dioxaborolane
metathesis.
PB
are
cross-linked
in
solution
using
photoinitiated
thiol-ene
click
chemistry.
As
targeted
cross-link
density
is
increased,
both
insoluble
fraction
and
glass-transition
temperature
increase.
Linear
viscoelasticity
studied
a
combination
small-amplitude
oscillatory
shear
(SAOS),
creep,
stress
relaxation
measurements.
SAOS,
elastic
modulus
approximately
constant
while
viscous
increases
as
angular
frequency
decreases.
compliance
displays
power
law
behavior
persists
for
at
least
8
h.
relaxation,
transitions
from
rubbery
plateau
into
regime.
Both
SAOS
creep
data
visually
superposed
master
curves
horizontal
shift
factors
exhibit
Arrhenius
behavior.
However,
application
these
determined
to
fails
align
single
curve.
(aSAOS)
collapse
short-time
data,
their
activation
energy
(EaSAOS)
matches
effective
Williams–Landel–Ferry
homopolymer,
indicating
dynamics
correspond
strand
segment
relaxations.
Creep
(acreep)
long-time
(Eacreep)
significantly
larger
than
energies
predicted
by
established
theoretical
models
transient
networks.
We
speculate
discrepancy
between
experiment
theory
due
dependence
cross-linker
mobility
within
matrix,
which
not
fully
captured
models.
ACS Sustainable Chemistry & Engineering,
Год журнала:
2023,
Номер
11(34), С. 12562 - 12570
Опубликована: Авг. 15, 2023
Dynamic
covalent
polymer
networks
(DCPNs)
with
self-healing
and
recycling
performance
are
highly
relevant
to
sustainable
development.
Disposal
of
plastic
wastes
generated
during
DCPN
reprocessing
still
faces
serious
challenges
deserves
be
explored.
Herein,
high-performance
polyacylsemicarbazide
(PASC)
DCPNs
exhibiting
excellent
properties
synthesized
by
the
reaction
sebacic
dihydrazide
isophorone
diisocyanate
hexamethylene
trimer.
Upcycling
PASC
waste
after
four-time
is
achieved
adding
epoxy
monomers
amine
curing
reagents,
followed
a
thermal
treatment.
The
optimized
resin
exhibits
tensile
strength
101
MPa,
Young's
modulus
2.73
GPa,
elongation
at
break
8.67%,
toughness
7.13
MJ·m–3,
Tg
140
°C,
Td
250
which
overall
surpass
those
original
DCPNs,
demonstrating
upcycling
performance.
recycled
from
carbon
fiber-reinforced
can
upcycled
using
same
strategy.
fiber
re-employed
prepare
composites
robust
mechanical
properties.
Given
low
cost
commercial
availability
monomers,
successful
not
only
reduces
environmental
pollution,
but
also
enables
possible
industrialization
contributes
circular
economy.
Microplastics,
Год журнала:
2024,
Номер
3(1), С. 184 - 204
Опубликована: Март 10, 2024
Environmental
pollution
caused
by
microplastics
has
evolved
into
a
global
concern;
however,
limited
knowledge
exists
about
in
soils
due
to
the
absence
of
standardized
extraction
methods.
This
research
aimed
develop
an
inexpensive,
rapid
method
with
user-friendly
and
environmentally
sustainable
outcomes
for
retrieval.
Three
salt
solutions
(Sodium
Chloride,
Magnesium
Sulfate,
Sodium
Hexametaphosphate)
oil
solution
(canola
oil)
underwent
evaluation
through
flotation
process
density
oleophilic
properties
plastics.
Four
widely
used
plastic
types,
obtained
fragmentation
using
grinding
mill
from
clean
new
containers
or
membranes,
were
subjected
analysis.
The
experimental
procedures
retrieval
varied
among
evaluated
solutions.
Through
comprehensive
multicriteria
analysis,
saturated
Chloride
emerged
as
optimal
scenario
extraction,
followed
closely
canola
scenario.
recovery
utilizing
demonstrated
economic
feasibility,
safety,
reliability.
study
provides
valuable
insights
effective
approach
mitigating
microplastic
soil,
offering
promising
avenue
future
environmental
conservation
efforts.
Macromolecules,
Год журнала:
2024,
Номер
57(12), С. 5747 - 5768
Опубликована: Июнь 6, 2024
Biobased
and/or
potentially
biodegradable
polymers
have
penetrated
the
market
over
last
years
as
sustainable
alternatives
to
their
fossil-based
equivalents,
driven
by
community's
increasing
sensitivity
environmental
issues.
Nonetheless,
replacing
with
bio-ones
will
not
just
resolve
all
problems,
and
recycling/upcycling
approaches
should
already
be
explored.
The
current
work
proposes
vitrimerization
an
alternative
route
for
upcycling
low
molecular
weight
polyesters
that
may
derive
from
end-of-life
waste,
(chemical)
recycling
residues,
or
hydrolyzed
in
intense
storage
conditions.
Utilizing
a
model
polyester,
poly(butylene
succinate)
(PBS),
two
sets
of
semi-crystalline
PBS
vitrimers
were
prepared,
cross-linked
either
diglycidyl
ether
bisphenol
A
(DGEBA)
glycerol
presence
Zn(II)
transesterification
catalyst.
By
tuning
cross–linker
type
loading
(0–10%
mol
respect
repeating
unit),
tailor–made
cross–linked
materials
prepared
high
insolubility
(gel
fraction
up
92%)
lower
swelling
(up
900%)
compared
conventionally
PBS,
well
enhanced
melt
strength
(4
orders
magnitude
increase
complex
viscosity).
characteristic
vitrimer
behavior
was
established
oscillatory
frequency
sweep
experiments
10,000%
modulus
at
120
°C)
rapid
stress
relaxation
(e.g.,
54–243
s
160
°C).
Interestingly,
reaction
temperature
found
only
influence
cross-link
density
attained,
while
molar
ratio
actual
cross-links
dominated
ability
network
rearrangement.
In
addition,
as-prepared
exhibited
improved
thermal
properties
stability
aged
polymer,
they
reprocessed
three
times
compression
molding
without
significant
loss
mechanical
performance
(tensile
strength,
Young's
modulus).
