Volume 53 Issue 9, September 2021

Our recent studies on the development of semiconducting polymers based on three novel π-extended heteropolycyclic aromatic frameworks, using phenanthro[1,2-b:8,7-b’]dithiophene (PDT) as a weak donor and alkoxy-substituted anthra[1,2‑c:5,6‑c’]bis([1,2,5]thiadiazole) (ATz) and vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (FBTzE) as new thiadiazole-based acceptor units are described. Furthermore, their detailed relationships between the thin-film structure and device performance in organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVs) were investigated. These results demonstrated that these novel π-extended heteropolycyclic aromatic frameworks have great potential as building units for high-performance OFETs and OPVs.

The copolymerization of β-substituted acrylates (i.e., crotonates and a cinnamate) using an organo-catalyzed group-transfer polymerization system with N-(tert-butyldimethylsilyl)bis(trifluoromethanesulfonyl)imide (Tf₂NSi^tBuMe₂) and 1-methoxy-1-(tert-butyldimethylsiloxy)-2-methyl-1-propene (^tBuMe2SKA) was investigated. The tert-butyldimethylsilyl moiety served as an effective means for suppressing the termination reactions of the GTP system. One-stage and two-stage copolymerization strategies employing different monomer feed methods were evaluated and gave random and block copolymers, respectively. The glass-transition temperatures of the prepared copolymers varied significantly depending on the comonomer used during the synthesis.

This study presents a facile method for preparation of water-soluble molecular complexes between carboxylic acid-functionalized multiwalled carbon nanotube and poly(2-methacryloyloxyethyl phosphorylcholine) (MWCNTs/PMPC) by hand grinding. MWCNTs could be solubilized in aqueous environment with higher suspended concentrations when increasing polymer concentration and pH of the solution. MWCNTs/PMPC adsorbed light and induced heat generation to reach the temperature required for photothermal therapy (PTT) when the complexes were irradiated by near-infrared (NIR) at a wavelength of 808 nm. The water-soluble MWCNT complex covered by biocompatible PMPC is a promising candidate for PTT application.

pH- and thermoresponsive polymer bearing pendant tertiary amino groups was grafted onto the surface of Resovist (PDMA@Rv). At pH 5.4, the grafted-polymer became hydrophilic, and the size of PDMA@Rv remained constant, irrespective of temperature. PDMA@Rv formed aggregates and showed lower critical solution temperature behavior above pH 7. PDMA@Rv contained a larger number of core particles of iron oxide than Resovist, which reduced the initial magnetic susceptibility due to the interaction of the core magnetic particles inside PDMA@Rv.

The oxidant addition time and polymerization time were varied during the synthesis of oligo(3-methoxythiophene), and the effect of such polymerization conditions on the physicochemical properties of the oligomer and its cast films was investigated. The polymerization conditions changed the oligomer molecular weight and the amount of edge-on lamellar crystallites in the films and, in turn, affected the color and gloss of the films. The obtained results are expected to facilitate the fabrication of conductive oligo(3-methoxythiophene) films with tunable color and metal-like luster for diverse applications.

We estimated the configurational heat capacity (C_config) of polyisobutylene (PIB), isobutane and 2,2,4-isomethylpentane above the glass transition temperature by reproducing the heat capacity in the solid state using molecular vibration analysis. This is the first time to estimate the C_config of polymer. The C_config decreased with increasing temperature for the three substances in this study. This is a similar pattern as the C_config of molecular glass from a simple molecular structure. Considering that the configuration entropy becomes a constant value at the high temperature limit because the molecules constituting the substance can take any configuration and orientation, it is considered reasonable that the C_config approaches zero at the high temperature limit.

Lignosulfonate is one of the major industrial products from wood. To utilize this compound as a moldable and strong material, we prepared a complex of lignosulfonate with cationic polyelectrolytes and reducing sugars. This complex contains two different crosslinking structures, i.e., ionic crosslinking between lignosulfonate and cationic polyelectrolytes and covalent crosslinking via the Maillard reaction of amino groups with reducing sugars. The coexisting of two different crosslinking greatly improved mechanical strength, Young’s modulus, water resistance, and adhesive strength compared with solely crosslinked complexes composed of the same ingredients.

Scaling relations of pulling translocation of a polymer globule through nanopores is studied by using the Langevin dynamics simulations. Under a constant pulling force, the scaling exponent is dependent on the intrapolymer interaction strength. Whereas under a constant pulling speed, it is independent of the intrapolymer interaction strength for sufficiently long polymer chains. The conformational changes of the polymer chain during the translocation and the entropic and enthalpic forces due to the straight conformation at the trans side play important roles on the pulling translocation of a polymer globule.

Over the past two decades, intensive efforts have been devoted to the development of group-10 metal catalysts, especially nickel and palladium ligated by unsymmetric bidentate ligands aimed at the copolymerization of olefins with polar monomers. Here we synthesized a palladium complex bearing a methoxyethoxygroup and applied it to the copolymerization of ethylene and methyl acrylate. Higher incorporation of methyl acrylate was detected in the presence of lithium borate such as LiBAr^F₄. The effect was limited to lithium, and the counteranion also affected the catalyst performance.