a b s t r a c tThe mechanism of how the neutral block in polyelectrolyte (PE) affects the interaction between PE and surfactants is investigated through coarse-grained simulations. We show that the neutral block plays profound roles on the structural formation of the PE/surfactant complex by assessing the adsorption of surfactants on a diblock or triblock PE and the resultant structures. For the diblock PE/surfactant system, adding a hydrophilic neutral block exerts little effect on the structural formation of the complex, while the presence of a hydrophobic neutral block enhances the adsorption of surfactants and facilitates the formation of a tri-layer core-shell structure. In the triblock PE/surfactant systems, two charged blocks located symmetrically at both ends of PE display asymmetric adsorption abilities for the surfactants. In addition, the presence of a charged middle block drives the PE/surfactant complex to form a micelle with two tails due to the hydrophilic blocks at both ends, while the hydrophobic ones drive the formation of a tri-layer core-shell structure with the PE chain showing a looped structure. If one end is hydrophilic and the other is hydrophobic, the complex tends to form a 'tadpole'-like structure in which the head is the tri-layered core-shell sphere, and the tail is the hydrophilic block.
Low
molecular weight gelators (LMWG) have been extensively explored
in many research fields due to their unique reversible gel–sol
transformation. Intermolecular interactions between LMWG are known
as the main driving force for self-assembly. During this self-assembly
process, individually analyzing the contribution difference between
various intermolecular interactions is crucial to understand the gel
properties. Herein, we report 2,5-bis(hexadecylcarbamoyl)terephthalic
acid (BHTA) as a LMWG, which could efficiently form a
stable organogel with n-hexadecane, diesel, liquid
paraffin, and base lubricant oil at a relatively low concentration.
To investigate the contribution difference of intermolecular interactions,
we first finished FT-IR spectroscopy and XRD experiments. On the basis
of the d-spacing, a crude simulation model was built
and then subjected to molecular dynamics (MD) simulations. Then, we
knocked out the energy contribution of the H-bonding interactions
and π–π stacking, respectively, to evaluate the
intermolecular interactions significantly influencing the stability
of the gel system. MD simulations results suggest that the self-assembly
of the aggregates was mainly driven by dense H-bonding interactions
between carbonyl acid and amide moieties of BHTA, which
is consistent with FT-IR data. Moreover, wave function analysis at
a quantum level suggested these electrostatic interactions located
in the middle of the BHTA molecule were surrounded by
strong dispersion attraction originating from a hydrophobic environment.
Furthermore, we also confirmed that 2 wt % BHTA was able
to form gel lubricant with 150BS. The coefficient of friction (COF)
data show that the gel lubricant has a better tribological performance
than 150BS base lubricant oil. Finally, XPS was performed and offered
valuable information about the lubrication mechanism during the friction.
Single crystals (15 × 15 µm) of lamellar JDF‐L1 and its analogues containing Al or Fe were synthesized by isomorphous substitution of tetrahedral Si sites by Al or Fe. The new (00n)‐plane epitaxial growth rises from the initial square sheets in a regularly orthogonal levo‐spiral mode.
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