Harvesting biobased epoxy resins
with improved thermomechanical
properties (e.g., glass transition temperature T
g and storage modulus), mechanical and dielectric similar and
even superior to that of bisphenol A epoxy resin (DGEBA) is vital
to many applications, yet remains a substantial challenge. Here we
develop a novel eugenol-based epoxy monomer (TEU-EP) with a branched
topology and a very rich biobased retention (80 wt %). TEU-EP can
be well cured by 3,3′-diaminodiphenyl sulfone (33DDS) and the
resultant TEU-EP/33DDS system can be considered as a “single”
epoxy component, exhibiting adequate reactivity at high processing
temperatures. Importantly, compared with DGEBA/33DDS, TEU-EP/33DDS
achieves a 33 °C, 39% and 55% increment in the glass transition
temperature, Young’s modulus, and hardness, respectively, and
shows the improved creep resistance and dimensional stability. TEU-EP/33DDS
is also characterized by the considerably reduced permittivity, dielectric
loss factor, and flammability with high yield of pyrolytic residual.
Overall, TEU-EP endows the cured epoxy with a number of the distinguished
properties outperforming its DGEBA counterpart, and therefore may
find practical applications in demanding and even cutting-edge areas.
In many fields, nanoparticles
are frequently dispersed onto kinds
of nanocarriers integrated into hybrid nanocomposites to acquire advanced
performance. However, the nanoparticles usually tend to agglomerate
on the surface, according to traditional synthetic methods. Besides,
the exposed state of loaded nanoparticles and the weak adhesion with
the supporters make them fall off during practical application, leading
to “second agglomeration” of the nanoparticles and attenuated
synergistic effects. In this work, we engineered layered bimetallic
(Ni–Co) hydroxides (NCHs) into enclosed nanocages derived from
metal organic frameworks (MOFs). Zinc hydroxystannate (ZHS) nanoparticles
were selected to be confined dispersed within the hollow cavity of
the three-dimensional nanocages. ZHS nanoparticles were tightly immobilized,
monodispersing to form a novel multiyolk@shell nanostructure with
NCH nanocages. To prove the effectiveness of this structural design,
the as-synthesized hybrids ZHS@NCH were introduced into the epoxy
matrix to inquiry its performance. Compared to neat ZHS, neat NCH,
and physical mixture of ZHS and NCH, ZHS@NCH conferred better flame
retardancy, thermal stability, and mechanical properties upon the
epoxy nanocomposites. With the adding amount of 6 wt % ZHS@NCH, the
UL-94 rating of the nanocomposite was V-0, and the peak of heat release
rate value was reduced by 69.1%, while the mechanical properties were
slightly influenced. The ingenious synthetic strategy gives insights
into uniform distribution of nanoparticles within nanocapsules and
enlightens the facile fabrication of multiyolk@shell nanomaterials.
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