2 research outputs found
Interfacial Activity of Starch-Based Nanoparticles at the Oil–Water Interface
Understanding the interfacial activity
of polysaccharide nanoparticles adsorbed at oil–water interfaces
is essential and important for the application of these nanoparticles
as Pickering stabilizers. The interfacial properties of starch-based
nanospheres (SNPs) at the interface of an <i>n</i>-hexane–water
system were investigated by monitoring the interfacial tension at
different bulk concentrations. The three-phase contact angle (θ)
and the adsorption energy (Δ<i>E</i>) increased with
increasing size and degree of substitution with octenyl succinic groups
(OSA) in the particles. Compared with the OSA-modified starch (OSA-S)
macromolecule, the SNPs effectively reduced the interfacial tension
of the <i>n</i>-hexane–water system at a relatively
higher concentration. These results and the method reported herein
are useful for selecting and preparing polysaccharide nanoparticles
as Pickering stabilizers for oil–water emulsions
Polyacrylonitrile-Coated Onion-like Carbon Nanoparticles for Carbon Nanofibers with Enhanced Strength and Toughness
Due to the typical strong and tough graphitic structures,
carbon
nanofibers (CNFs) theoretically have excellent mechanical properties.
However, in practice, the defects and misalignments in these crystal
domains always jeopardize the performance of CNFs and limit their
further application. In this case, this paper takes onion-like carbon
(OLC) as an effective nanofiller to optimize the fiber graphitic structure
and produces composite CNFs with enhanced strength and toughness.
For this purpose, the in situ polymerization technique is specially
developed for the rapid and uniform distribution of OLC in the polyacrylonitrile
(PAN) precursor of CNFs. The obtained PAN-coated OLC nanoparticles
successfully avoid the agglomeration of nanofillers and can be further
electrospun into OLC uniformly doped PAN nanofibers. Owing to the
interaction between OLC and PAN matrix, the crystal domains in PAN
precursor nanofibers are thicker and transformed from integrated shish-kebab
structures into nanofibril crystals with better regularity and orientation.
In the subsequent stabilization and carbonization processes, these
crystalline nanofibrils are considered to be the structural basis
for the formation of oriented and continuous graphitic domains in
final CNFs. Meanwhile, the graphitic shells of OLC are confirmed to
act as the template in the carbonization process to induce and promote
the crystallization of the surrounding fiber matrix and transform
the turbostratic structures in fiber crystal domains into more orderly
graphitic structures with increased size and continuity. Furthermore,
the embedded nanoscale OLC can co-move and continuously interact with
the resulting graphitic domains during the deformation process for
load transfer. As a result, the tensile strength and elongation at
break of OLC-reinforced CNFs increase by 53.5 and 34.0%, respectively.
The strong and tough composite CNFs may help to avoid the potential
fiber breaking in their practical use and be further applied in wearable
capacitors, masks, filters, etc