With
the popularization of 5G communications and the internet of
things, electromagnetic wave (EW) radiation pollution has aroused
much concern from the public, and the search for new materials and
technologies for preparing electromagnetic shielding materials still
continues all around the world. However, the contradiction among high
shielding performance, economic applicability, and flexibility is
still not well balanced. Herein, we fabricated a novel foldable leather
solid waste (LSW)/polyvinyl alcohol (PVA)/silver (Ag) paper with excellent
electromagnetic interference (EMI)-shielding ability using a facile
but sustainable electroless plating (ELP) method with LSW as the resource.
Taking PVA as a cross-linker, debundled leather fibers (LFs) generated
by solid-state shearing milling could generate a flexible LSW/PVA
substrate with a high specific surface area, and eventually the deposited
Ag layer served as a protective layer not only to significantly improve
the mechanical and thermal robustness, but also to endow the LSW/PVA/Ag
paper with good hydrophobicity, which could protect from potential
moisture damage. In addition to the reflection effect of metallic
Ag on EW, the hierarchical structure of collagen fibers played an
important role in superior high EMI-shielding effectiveness (∼55–∼90
dB) by an absorption-dominant EMI-shielding mechanism. Furthermore,
a multilayer LSW/PVA/Ag paper was also prepared with enhanced EMI-shielding
effectiveness of 111.3 dB benefited by constructing multiple reflection–absorption
interfaces. The high-performance, environmentally friendly, and low-cost
EMI-shielding materials not only offered a new avenue toward recycling
LSW in a more value-added way, but also displayed promising potential
for application in flexible shielding materials or wearable clothing.
Renewable biobased aerogels display a promising potential to fulfill the surging demand in various industrial sectors. However, its inherent low mechanical robustness, flammability, and lack of functionality are still huge obstacles in its practical application. Herein, a novel integrated leather solid waste (LSW)/ poly(vinyl alcohol) (PVA)/polyaniline (PANI) aerogel with high mechanical robustness, flame retardancy, and electromagnetic interference (EMI) shielding performance was successfully prepared. Amino carboxyl groups in LSW could be effectively exposed by solid-state shear milling (S 3 M) technology to form strong hydrogen-bond interactions with the PVA molecular chains. This led to a change in the compressive strength and the temperature of the initial dimensional change to 15.6 MPa and 112.7 °C at a thickness of 2.5 cm, respectively. Moreover, LSW contains a large number of N elements, which ensures a nitrogen-based flame-retardant mechanism and increase in the limit oxygen index value of LSW/PVA aerogel to 32.0% at a thickness of 2.5 mm. Notably, by the cyclic coating method, a conductive PANI layer could be polymerized on the surface of LSW/PVA aerogel, which led to the construction of a sandwich structure with impressive EMI shielding capability. The EMI shielding effectiveness (SE) reached more than 40 dB, and the specific shielding effectiveness (SSE) reached 73.0 dB cm 3 g −1 . The inherent dipoles in collagen fibers and the conductive PANI synergistically produced an internal multiple reflection and absorption mechanism. The comprehensive performance of LSW/PVA/PANI aerogel not only demonstrates a new strategy to recycle LSW in a more value-added way but also sheds some more light on the development of biomass aerogels with high-performance, environmentally friendly, and cost-effective properties.
Under
the threat of environmental pollution caused by waste plastics,
environmentally friendly and biodegradable materials with superior
performance have attracted worldwide public attention. Herein, by
combining solid-state shear milling (S3M) and biaxial stretching
technologies, high-performance and environmentally friendly poly(vinyl
alcohol) (PVA)/kaolin barrier films used for packaging were fabricated.
The highly effective S3M technology simultaneously achieved
the in situ exfoliation and superior dispersion of layered kaolin
in the PVA matrix at ambient temperature. These kaolin nanoflakes
featured a thickness of ∼3 nm and a width of ∼70 nm,
thus effectively blocking the movement of PVA molecular chains and
leading to the increase of glass transition temperature (T
g) as well as the initial degradation temperature of the
PVA matrix. By further synchronously biaxial stretching, benefiting
from the well-dispersed kaolin and the oriented PVA molecular chains,
the obtained anisotropic composite film with 5 wt % kaolin exhibited
extremely high yield strength (138.7 MPa), tensile strength (146.4
MPa), and Young’s modulus (5.5 GPa), as well as excellent ultraviolet
(UV) and oxygen barrier properties. This work not only highlights
a novel strategy for achieving synchronous exfoliation and dispersion
of layered clay minerals in a polymer matrix but also facilitates
the green development of high-performance polymer-based films used
for packaging.
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