Modelling Development in Radical (Co)Polymerization of Multivinyl Monomers.

Radical polymerization (RP) of multivinyl monomers (MVMs) provides a facile solution for manipulating polymer topology and has received increasing attention due to their industrial and academic significance. Continuous efforts have been made to understand their mechanism, which is the key to regulating materials structure. Modelling techniques have become a powerful tool that can provide detailed information on polymerization kinetics which is inaccessible by experiments. Many publications have reported the combination of experiments and modelling for free radical polymerization (FRP) and reversible-deactivation radical polymerizations (RDRP) of MVMs. Herein, a minireview is presented for the most important modelling techniques and their applications in FRP/RDRP of MVMs. This review hopes to illustrate that the combination of modelling and wet experiments can be a great asset to polymer researchers and inspire new thinking for the future MVMs experiment optimization and product design.

Monte Carlo studies of two-dimensional polymer-solvent systems.

The static properties of two-dimensional athermal polymer solutions were studied by performing Monte Carlo lattice simulations using the cooperative motion algorithm (CMA) and taking into account the presence of explicit solvent molecules. The simulations were performed for a wide range of polymer chain lengths N (16-1024) and concentrations φ (0.0156-1). The results obtained for short chains (N < 256) were in good agreement with those given by previous simulations. For the longest chains (512 or 1024 beads), some unexpected behavior was observed in the dilute and semidilute regimes. A pronounced change in the concentration dependence of chain size and shape was observed below a certain critical concentration (0.6 for the longest chains under consideration, consisting of 1024 beads). Longer chains became more extended below this concentration. The behavior of the single-chain structure factor confirmed these changes in the fractal dimension of the chain as a function of the concentration. The observed phenomena are related to the excluded volume of solvent molecules, which causes the chain statistics to be modified in the vicinity of other chains; this effect is important in strictly 2D systems. Graphical abstract Extended long chains at moderate density with solvent molecules inside coils.

Synthesis and optoelectronic properties of hexahydroxylated 10-O-R-substituted anthracenes via a new modification of the Friedel-Crafts reaction using O-protected ortho-acetal diarylmethanols.

A new modification of the Friedel-Crafts type intramolecular cyclization involving O-protected ortho-acetal diarylmethanols as a new type of reactant, was carried out for the first time in a medium containing a large amount of water at room temperature and enabled synthesis of a series of electron-rich, hexahydroxylated 10-O-R-substituted anthracenes, where R is an alkyl (Me, nBu, n-C(16)H(33)) or arylalkyl group (CH(2)Ph, CH(2)-2-Napht, CH(2)C(6)H(4)CH(2)OAr) and also evaluation of their electronic and optoelectronic properties in solution, crystal, and solid thin film. In this transformation, a central 10-O-R-substituted benzene ring was formed, fused to rings originating from two independent aromatic aldehydes. The reaction proceeded via two identified mechanisms involving acetal and/or free aldehyde groups. The acid sensitive acetal and dibenzyl alkoxy functions have never been used together in the intramolecular Friedel-Crafts type cyclization. The new compounds revealed deep blue fluorescence and quantum yields in solution around 0.3. The electrical properties investigated for thin films obtained by vacuum deposition on glass were 10-O-R-substituent dependent and showed much faster transient current decay in the case of the 10-O-CH(2)Ph derivative than for the material with a 10-O-Me substituent (the lifetime of charge carriers was 25 times shorter in this case). The AFM images of thin films, Stokes shifts, and X-ray analysis of π-stacking interactions in crystals of the new materials have been also obtained.

Microphase separation in two-dimensional athermal polymer solutions on a triangular lattice.

The results of Monte Carlo simulations of 2D polymer solutions are presented. The simulations were performed under athermal conditions for long chains (up to 1024 beads) over a full range of polymer concentration phi, explicitly taking into account the solvent molecules. The results obtained for short chains (N < or = 256) are in good agreement with previous simulations whereas for long chains microphase separation is observed below phi = 0.6. This phenomenon is attributed to strong excluded volume interactions in 2D systems. A sort of interpenetration of the coils is also observed.

The solid-state synthesis of metal nanoparticles from organometallic precursors.

Nanoparticles (NPs), average size of 2-5 nm, of ruthenium, cobalt, and rhodium have been prepared by an original method, namely the solid-state decomposition under dihydrogen of an organometallic precursor either dispersed in polymer films or directly as nanocrystals. The NPs dispersion, size, and morphology are investigated by transmission electron microscopy, and their structure by wide angle X-ray scattering. Infrared spectroscopy, after adsorption of carbon monoxide on the metal NPs surfaces, evidences a nonoxidized surface of high reactivity.

Uniaxial alignment of the columnar super-structure of a hexa (alkyl) hexa-peri-hexabenzocoronene on untreated glass by simple solution processing.

Uniaxially aligned, thin films of a discotic columnar thermotropic liquid crystalline material can be prepared by a simple solution zone-casting method, without the need for modified surfaces or traditional alignment techniques. Atomic force microscopy together with X-ray diffraction reveals single-crystalline-like order over several square centimeters, far exceeding the requirements for application of such films in organic molecular electronic devices such as field-effect transistors.