33 research outputs found
Correction: A low cost azomethine-based hole transporting material for perovskite photovoltaics
No abstract available
Double helical conformation and extreme rigidity in a rodlike polyelectrolyte
The ubiquitous biomacromolecule DNA has an axial rigidity persistence length
of ~50 nm, driven by its elegant double helical structure. While double and
multiple helix structures appear widely in nature, only rarely are these found
in synthetic non-chiral macromolecules. Here we describe a double helical
conformation in the densely charged aromatic polyamide
poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) or PBDT. This double helix
macromolecule represents one of the most rigid simple molecular structures
known, exhibiting an extremely high axial persistence length (~1 micrometer).
We present X-ray diffraction, NMR spectroscopy, and molecular dynamics (MD)
simulations that reveal and confirm the double helical conformation. The
discovery of this extreme rigidity in combination with high charge density
gives insight into the self-assembly of molecular ionic composites with high
mechanical modulus (~1 GPa) yet with liquid-like ion motions inside, and
provides fodder for formation of new 1D-reinforced composites.Comment: Accepted for publication by Nature Communication
Phase Behavior of Bent-Core Molecules
Recently, a new class of smectic liquid crystal phases (SmCP phases)
characterized by the spontaneous formation of macroscopic chiral domains from
achiral bent-core molecules has been discovered. We have carried out Monte
Carlo simulations of a minimal hard spherocylinder dimer model to investigate
the role of excluded volume interations in determining the phase behavior of
bent-core materials and to probe the molecular origins of polar and chiral
symmetry breaking. We present the phase diagram as a function of pressure or
density and dimer opening angle . With decreasing , a transition
from a nonpolar to a polar smectic phase is observed near ,
and the nematic phase becomes thermodynamically unstable for . No chiral smectic or biaxial nematic phases were found.Comment: 4 pages Revtex, 3 eps figures (included
Molecular composites based on high-performance polymers and an interpenetrating liquid crystal thermoset
The invention is directed to a polymeric composition comprising a first polymer (in particular HPP) and a liquid crystal thermoset (LCT) network that interpenetrates said first polymer, which LCT network comprises LCT oligomers that are at least partly polymerized, as well as to a method for preparing such. The polymeric composition of the invention does not separate into two distinct polymer phases (first polymer and LCT) over time and has improved thermo-mechanical properties. In particular, the invention may be used to improve the properties of HPP. The polymeric composition can be used as a high-resistant material, in particular having improved heat resistance.ChemE/Chemical EngineeringApplied Science
Small azomethine molecules and their use in photovoltaic devices
The present invention is in the field of a small azomethine molecule having photovoltaic characteristics, a method of synthesizing said molecule, use of said molecule in a photovoltaic device, a solar cell comprising said molecule, and a film comprising said molecule. The present molecules may find application in the field of organic solar cells.ChemE/Chemical EngineeringApplied Science
Concept-Eindverslag Commissie Erfrecht KNB inzake Boek 4 BW
Contains fulltext :
85134.pdf (publisher's version ) (Open Access)12 p
Concept-Eindverslag Commissie Erfrecht KNB inzake Boek 4 BW (II, slot)
Contains fulltext :
85135.pdf (publisher's version ) (Open Access)6 p
Gas transport in metal organic framework-polyetherimide mixed matrix membranes: The role of the polyetherimide backbone structure
We report on how the morphology of the polymer matrix, i.e. amorphous vs. semi-crystalline, affects the gas transport properties in a series of mixed matrix membranes (MMMs) using Cu3(BTC)2 as the metal organic framework (MOF) filler. The aim of our work is to demonstrate how incorporation of Cu3(BTC)2 affects the polyetherimide matrix morphology and thereby highlighting the importance of selecting the appropriate polyetherimide matrix for mixed matrix membranes. We used three amorphous poly(etherimide)s with very similar backbone structures. Polyetherimide ODPA-P1 was used as a linear flexible matrix, aBPDA-P1 is a non-linear rigid matrix and 6FDA-P1 was selected because the backbone structure is similar to ODPA-P1 but replacing the oxygen linker with two bulky –CF3 groups results in a linear polymer with a low chain packing efficiency. Using an in-situ polymerization technique, up to 20 wt.% Cu3(BTC)2 could be homogenously dispersed in all three PEIs. The ODPA-P1 matrix crystallized when Cu3(BTC)2 was introduced as a filler. Gas permeation studies were performed by analyzing membrane performance using a 50:50 CO2:CH4 mixed gas feed. The presence of crystalline domains in ODPA-P1 resulted in a decrease in permeability for both CO2 and CH4 but the selectivity increased from 41 to 52 at 20 wt.% Cu3(BTC)2. The non-linear, rigid, aBPDA-P1 matrix remains amorphous when Cu3(BTC)2 is introduced. SEM images of the MMM cross-section revealed a sieve-in-a-cage morphology and at 20 wt.% Cu3(BTC)2, the permeation of both CO2 and CH4 increased by 68% thereby negating any change in selectivity. For 6FDA-P1 with 20 wt.% Cu3(BTC)2, only the permeability of CO2 increased by 68% resulting in an increase in selectivity of 33