Search results for "AIC"

Competition between degradation and chain extension during processing of reclaimed poly(ethylene terephthalate)

1998

During processing of poly(ethylene terephthalate) (PET) hydrolytic chain scission, induced by the presence of small amounts of water, is the main cause of degradation. During repeated reprocessing chain scission can also occur because of the presence of other polymeric contaminants like PVC. In order to avoid or to limit hydrolytic chain cleavage adequate drying of PET before melt processing is necessary. Of course this practice is even more recommended when repeated processing steps are used, as for PET recycling. The behavior of recycling PET obtained from post-consumer water bottles when treated in a melt mixer under different conditions has been investigated in order to better understan…

DFT study of the interaction free energy of p–p complexes of fullerenes with buckybowls and viologen dimers

2011

We present a theoretical investigation, by means of DFT protocols, of the complexation thermodynamics of (i) complexes of C70 and C60 fullerenes with bowl-shaped hexabenzocoronene derivatives and (ii) complexes of C60 with viologen dimers. The recent functionals of the M06 family, accounting for p-p interactions to a good level of approximation, have been used to calculate the interaction free energies. For the former complexes, the good agreement between the calculated results and the experimental data confirms the reliability of the protocol used. On these grounds, we then checked the stability of a series of complexes of C60 with some viologen dimers, 1BPnBP1 (n = 6-9), where two N-methy…

Design, synthesis and photovoltaic properties of [60]fullerene based molecular materials

2005

Abstract The possibility to use new organic semiconductor materials, in place of silicon wafers, in the fabrication of photovoltaic devices on substrates offer the prospect of lower manufacturing costs, particularly for large area applications. Thus, one of the most promising areas in fullerene research involves its potential application, mixed with conjugated polymers, in mimicking photosynthesis and in the related solar energy conversion. The tendency to phase segregation in blends of C60 derivatives and conjugated polymers has to be optimized to improve both charge photogeneration and transport in photovoltaic devices. In order to optimize device performances, a great deal of work has be…

1988

Monte Carlo simulations are presented for binary (AB) symmetric polymer mixtures (chain lengths NANBN) for the case that an attractive interaction ϵ exists between monomers of the same kind, and the limiting case that one species (B) is very diluted. It is shown that with increasing interaction strength ϵ/(kB · T), T being the absolute temperature, the minority chains collapse to a very dense configuration, while the majority chains stay nearly Gaussian. Both chain radii, structure factors and numbers of nearest neighbour contacts are discussed.

Hierarchy of Asymmetry at Work: Chain-Dependent Helix-to-Helix Interactions in Supramolecular Polymers.

2018

A detailed investigation of the hierarchy of asymmetry operating in the self-assembly of achiral (1) and chiral ((S)-2 and (R)-3) 1,3,5-triphenylbenzenetricarboxamides (TPBAs) is reported. The aggregation of these TPBAs is conditioned by the point chirality at the peripheral side chains for (S)-2 and (R)-3. An efficient helix-to-helix interaction that goes further in the organization of fibrillar bundles is experimentally detected and theoretically supported only for the achiral TPBA 1. The effective interdigitation of the achiral aliphatic side chains produces a social self-sorting to form preferentially heterochiral macromolecular aggregates.

A new copper chloride chain by supported hydrogen bonding

2013

In the current paper we introduce a new type of Cu–Cl polymer ([H2bipip]2+[CuCl3]2−)n. In this polymer the trigonal CuCl3 units are covalently linked via chloride bridges. The structure is supported by the bipiperidinium cation ([H2bipip]2+) via hydrogen bonds. The cation plays an essential role in formation of the polymeric structure. The closely related piperazinium (H2pip)2+ cation also leads to a hydrogen bonded assembly of CuCl3 ([H2pip]2+[CuCl3]2−), but a covalently bound polymer was not obtained.

Mixed Iodide-Bromide Methylammonium Lead Perovskite-based Diodes for Light Emission and Photovoltaics.

2015

Vacuum deposition techniques are used to prepare mixed iodide–bromide methylammonium lead perovskite diodes via an intermediate double layer of the pure iodide and bromide perovskites. The diodes lead to bright electroluminescence, whose emission spectra maxima shift from the infrared toward the visible with increasing bromide content. When illuminated with AM1.5 simulated sunlight the devices function as efficient solar cells with power conversion efficiencies as high as 12.9%.

Dragging a Polymer Chain into a Nanotube and Subsequent Release

2008

We present a scaling theory and Monte Carlo (MC) simulation results for a flexible polymer chain slowly dragged by one end into a nanotube. We also describe the situation when the completely confined chain is released and gradually leaves the tube. MC simulations were performed for a self-avoiding lattice model with a biased chain growth algorithm, the pruned-enriched Rosenbluth method. The nanotube is a long channel opened at one end and its diameter $D$ is much smaller than the size of the polymer coil in solution. We analyze the following characteristics as functions of the chain end position $x$ inside the tube: the free energy of confinement, the average end-to-end distance, the averag…

Conformational studies of hexapeptides containing two dehydroamino acid residues in positions 2 and 5 in peptide chain

2008

Conformational preferences of a group of hexapeptides containing two dehydroamino acid residues in Positions 2 and 5 in peptide chain were investigated by means of spectroscopic methods (NMR and CD) and theoretical calculations. In the case of dimethylsulfoxide (DMSO) solution, only peptide with free N-termini adopted rigid 310-helical conformation, for the rest of examined peptides extended and “zig-zag” conformers were predominant. CD measurements showed that only in chloroform solution the conformational freedom of investigated peptides was restricted. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 691–699, 2008. This article was originally published online as an accepted preprint. The “…

Phase Separation and Nematic Order in Lyotropic Solutions: Two Types of Polymers with Different Stiffnesses in a Common Solvent

2021

The interplay of the isotropic-nematic transition and phase separation in lyotropic solutions of two types of semiflexible macromolecules with pronounced difference in chain stiffness is studied by Density Functional Theory and Molecular Dynamics simulations. While the width of the isotropic-nematic two-phase coexistence region is narrow for solutions with a single type of semiflexible chain, the two-phase coexistence region widens for solutions containing two types of chains with rather disparate stiffness. In the nematic phase, both types of chains contribute to the nematic order, with intermediate values of the order parameter compared to the corresponding single component solutions. As …