7,720 research outputs found
Review on Blueprint of Designing Anti-Wetting Polymeric Membrane Surfaces for Enhanced Membrane Distillation Performance
Recently, membrane distillation (MD) has emerged as a versatile technology for treating saline water and industrial wastewater. However, the long-term use of MD wets the polymeric membrane and prevents the membrane from working as a semi-permeable barrier. Currently, the concept of antiwetting interfaces has been utilized for reducing the wetting issue of MD. This review paper discusses the fundamentals and roles of surface energy and hierarchical structures on both the hydrophobic characteristics and wetting tolerance of MD membranes. Designing stable antiwetting interfaces with their basic working principle is illustrated with high scientific discussions. The capability of antiwetting surfaces in terms of their self-cleaning properties has also been demonstrated. This comprehensive review paper can be utilized as the fundamental basis for developing antiwetting surfaces to minimize fouling, as well as the wetting issue in the MD process
Quantum scale biomimicry of low dimensional growth: An unusual complex amorphous precursor route to TiO2 band confinement by shape adaptive biopolymer-like flexibility for energy applications
Crystallization via an amorphous pathway is often preferred by biologically driven processes enabling living species to better regulate activation energies to crystal formation that are intrinsically linked to shape and size of dynamically evolving morphologies. Templated ordering of 3-dimensional space around amorphous embedded non-equilibrium phases at heterogeneous polymer-metal interfaces signify important routes for the genesis of low-dimensional materials under stress-induced polymer confinement. We report the surface induced catalytic loss of P=O ligands to bond activated aromatization of C-C C=C and Ti=N resulting in confinement of porphyrin-TiO(2 )within polymer nanocages via particle attachment. Restricted growth nucleation of TiO2 to the quantum scale (˂= 2 nm) is synthetically assisted by nitrogen, phosphine and hydrocarbon polymer chemistry via self-assembly. Here, the amorphous arrest phase of TiO, is reminiscent of biogenic amorphous crystal growth patterns and polymer coordination has both a chemical and biomimetic significance arising from quantum scale confinement which is atomically challenging. The relative ease in adaptability of non-equilibrium phases renders host structures more shape compliant to congruent guests increasing the possibility of geometrical confinement. Here, we provide evidence for synthetic biomimicry akin to bio-polymerization mechanisms to steer disorder-to-order transitions via solvent plasticization-like behaviour. This challenges the rationale of quantum driven confinement processes by conventional processes. Further, we show the change in optoelectronic properties under quantum confinement is intrinsically related to size that affects their optical absorption band energy range in DSSC.This work was supported by the National Research Foundation of Korea (NRF) grant funded by Korea government (MEST) NRF-2012R1A1A2008196, NRF 2012R1A2A2A01047189, NRF 2017R1A2B4008801, 2016R1D1A1A02936936, (NRF-2018R1A4A1059976, NRF-2018R1A2A1A13078704) and NRF Basic Research Programme in Science and Engineering by the Ministry of Education (No. 2017R1D1A1B03036226) and by the INDO-KOREA JNC program of the National Research Foundation of Korea Grant No. 2017K1A3A1A68. We thank BMSI (A*STAR) and NSCC for support. SJF is funded by grant IAF25 PPH17/01/a0/009 funded by A* STAR/NRF/EDB. CSV is the founder of a spinoff biotech Sinopsee Therapeutics. The current work has no conflicting interests with the company. We would like to express our very great appreciation to Ms. Hyoseon Kim for her technical expertise during HRTEM imaging
Modeling elastic properties of polystyrene through coarse-grained molecular dynamics simulations
This paper presents an extended coarse-grained investigation of the elastic
properties of polystyrene. In particular, we employ the well-known MARTINI
force field and its modifications to perform extended molecular dynamics
simulations at the s timescale, which take slow relaxation processes of
polystyrene into account, such that the simulations permit analyzing the bulk
modulus, the shear modulus, and the Poisson ratio. We show that through the
iterative modification of MARTINI force field parameters it turns out to be
possible to affect the shear modulus and the bulk modulus of the system, making
them closer to those values reported in the experiment.Comment: 29 pages, 8 figure
Phase separation and self-assembly in vitrimers: hierarchical morphology of molten and semi-crystalline polyethylene/dioxaborolane maleimide systems
Vitrimers - a class of polymer networks which are covalently crosslinked and
insoluble like thermosets, but flow when heated like thermoplastics - contain
dynamic links and/or crosslinks that undergo an associative exchange reaction.
These dynamic crosslinks enable vitrimers to have interesting
mechanical/rheological behavior, self-healing, adhesive, and shape memory
properties. We demonstrate that vitrimers can self-assemble into complex meso-
and nanostructures when crosslinks and backbone monomers strongly interact.
Vitrimers featuring polyethylene (PE) as the backbone and dioxaborolane
maleimide as the crosslinkable moiety were studied in both the molten and
semi-crystalline states. We observed that PE vitrimers macroscopically phase
separated into dioxaborolane maleimide rich and poor regions, and characterized
the extent of phase separation by optical transmission measurements. This phase
separation can explain the relatively low insoluble fractions and overall
crystallinities of PE vitrimers. Using synchrotron-sourced small-angle X-ray
scattering (SAXS), we discovered that PE vitrimers and their linear precursors
micro-phase separated into hierarchical nanostructures. Fitting of the SAXS
patterns to a scattering model strongly suggests that the nanostructures -
which persist in both the melt and amorphous fraction of the semi-crystalline
state - may be described as dioxaborolane maleimide rich aggregates packed in a
mass fractal arrangement. These findings of hierarchical meso- and
nanostructures point out that incompatibility effects between network
components and resulting self-assembly must be considered for understanding
behavior and the rational design of vitrimer materials
Flaw-tolerance in silk fibrils explains strength, extensibility and toughness of spider silk
Silk is an ancient but remarkably strong, extensible and tough material made from simple protein building blocks. Earlier work has shown that the particular molecular geometry of silk with a composite of semi-amorphous and nanocrystalline beta-sheet protein domains provides the structural basis for its characteristic softening-stiffening behavior and remarkable strength at the nanoscale. Yet, an open question remains as to how these nanoscale properties are upscaled so effectively to create strong, extensible and tough silk fibers. Here we discover that the geometric confinement of fibrils to ≈50-100 nm width and arranged in bundles to form larger-scale silk fibers, is the key to explaining the upscaling of the mechanical properties of silk from the atomistic scale upwards. We find that under this geometric confinement, hundreds of thousands of protein domains unfold simultaneously and thereby act synergistically to resist deformation and failure, providing access to enhanced large-scale strength, extensibility and toughness. Moreover, since the material is in a flaw-tolerant state under this geometric confinement, structural inhomogeneities such as cavities or tears that typically act as stress concentrators do not compromise the material performance. Indeed, experimental work showed that the diameter of silk fibrils that make up larger-scale silk fibers are on the order of 20-100 nm, in agreement with our findings. The exploitation of this mechanism in engineering design enables the synthesis of hierarchical fiber materials for superior performance despite limited and inferior building blocks
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