Original Article in 2018

Time-resolved synchrotron small- and wide-angle X-ray scattering was carried out during the high-speed elongation of unoriented exclusively β-crystal-containing isotactic polypropylene. In the first stage, microvoid formation started. In the second stage, separation of crystalline block, unfolding, and withdrawing of the crystalline chains were occurred. And then the β–α transformation produced a highly oriented α-crystal parallel to the elongation direction. In the third stage, lamellae underwent inter- and intralamellar slipping and fragmentation and then unfolded to produce the oriented α-crystal.

Thermal behavior, molecular aggregation structure, and water repellency of a comb-shaped fluoropolymer, poly{2-[(perfluorooctylethyl)carbamate]ethyl}acrylate (PFAUr-C₈), were investigated. PFAUr-C₈ exhibited polymorphic ordered structures, where the stacked lamellar structure of R_f side chains was maintained without their lateral translational order. The cohesive dipolar interactions in the carbamate linkers would induce the thermal stability of the lamellar structure. PFAUr-C₈ exhibits superior water repellency.

The network structure evolution of a hexamethylenetetramine-cured novolac-type phenolic resin was investigated using ¹H-pulse NMR spectroscopy, SAXS and WAXS to elucidate the mechanism responsible for the apparent absence of inhomogeneity after curing, in which the inhomogeneity was first observed at the gel point.

We developed 2,5-furanylene sulfide-containing polymers bearing different spacers as repeating units and evaluated the interactions between the furanylene sulfide units in the polymer. Treatment of a 2,5-dichlorofuran derivative with dithiolates at 200 °C promotes polycondensation via nucleophilic aromatic substitution to give the corresponding furanylene sulfide-containing polymers. Through tensile measurements and spectral analyses, it was found that the furanylene sulfide moieties form remarkably stable π–π stacking structures based on the enhanced dipole moment induced by sulfur linkages. When the polymer has a long spacer between repeating furanylene sulfide units, the polymer behaves as a chemically stable network polymer comprised of π–π stacking structures as cross-linking units.

We crosslinked polythiophenes with disiloxane groups in its side chains by dicumyl peroxide. The crosslinked polythiophenes maintained low glass transition temperatures and low Young’s modulus, while they emerged high elastic recoveries. Moreover, as the concentration of dicumyl peroxide increased, the crosslinked polythiophenes possessed higher elastic recoveries. We obtained completely elastic semiconductive polythiophenes.

The synthesis of carboxylated IIR was achieved in high yield starting from brominated substrates, which were first converted to azides and used in the copper-catalyzed azide–alkyne Huisgen cycloaddition reaction with acetylenic acids containing different aliphatic spacer lengths. Optimization of the reaction conditions was critical to avoid the formation of gel particles in the reactions and to achieve full conversion of the bromide to carboxylate derivatives.

Designer supramolecular polymers are a growing field of polymer materials. The designability and flexibility in their structures and functionality have attracted a great deal of attention in polymer science, as well as in supramolecular chemistry. These polymeric structures are formed from one or more molecular components via reversible bonds; therefore, monomeric and polymeric states are in equilibrium on the relevant experimental timescale. The dynamic nature of supramolecular polymers in terms of chain lifetime and conformational flexibility are determined by external conditions. This adaptivity can result in stimuli-responsive structures and properties. This article describes the use of our host–guest structures based on a calix[5]arene, a bisporphyrin, and a self-assembled capsule in the synthesis of supramolecular polymers.

Poly(methyl methacrylate) smart xerogels (PAsp-xgs) crosslinked by polyaspartate side chains were synthesized and the effects of the polyaspartate helix-sense inversion on their properties were investigated. PAsp-xg was found to irreversibly shrink to a volume ratio of 0.7 when heated to ~393 K. The volume shrinkage was suggested to be induced by the helix-sense inversion of the polyaspartates in the hybrid xerogels.

Conducting polymers were synthesized via in situ polymerization, using nanoclay bentonite sodium and its modified form. The polymer nanoclay modified form showed enhanced solubility compared to the original polymers and improved thermal stability, along with higher corrosion inhibition efficiency and aggregation-induced emission with luminescence dependent on the aggregate structure.

The effect of trialkylaluminium compound (AlR₃, where R = Me, Et, iBu) addition on the performance of the transition metal complex/AliBu₃/Ph₃CB(C₆F₅)₄ catalysts in ethylene/1-olefin copolymerization was investigated. It was shown that AlR₃ may affect the catalytic properties of the system (activity, comonomer incorporation, and copolymer microstructure). This influence is dependent on the type of organoaluminum compound and on the structure of the complex, i.e., on the structure of the ligand and on the type of transition metal.

Taking advantage of the flexible movement for the benzotriazole in the side chains, the resulting membranes exhibit encouraging proton conductivities and fuel cell performance.

The adhesion force between the tentacle of a live cypris and polymer brushes on the sidewall of cover glass was directly measured by scanning probe microscopy in seawater. The cypris was immobilized on the cantilever with glue, and then forced to make contact with the modified surface. When the tentacle was detached by moving the cantilever away from the surface, the torsion of the cantilever caused the laser deflection on the photodiode corresponding to the adhesion force. Polymer brush surfaces exhibited extremely low adhesion to the cypris larva.

Conjugated polymers of diketopyrrolopyrrole (DPP) and thiophene, especially 2,5-di-2-thienyl-thieno[3,2-b]thiophene, were characterized by their molecular packing orientation with a π-π stacking distance of 3.6 Å and a high field-effect hole mobility on the order of 10⁻² cm²/Vs. A perovskite solar cell, fabricated with the genuine or both oxidizing and salt dopant-free polymer as a hole-transporting layer, displayed a high photo-conversion efficiency of 16.3% with high durability.

The friction properties of a dilute solution of block copolymer additives in a base lubricant oil confined between mica surfaces were investigated using the surface forces apparatus. Friction force, sliding film thickness, and contact geometry were evaluated in detail, and the results were compared to those of the solutions of a different block copolymer additive having similar molecular structure. The relationship between the chemical structure of additives, confined structures between surfaces, and friction mechanisms were discussed, which shed new light of the design of low-friction surfaces in oil-based lubrication.

Highly porous organic structures are synthesized by the oxidative polymerization of pyrrole derivatives in a concentrated monomer and oxidant solution. The rapid polymerization of pyrrole derivatives by oxidation with FeCl₃ in CHCl₃ as a cosolvent for the monomer and the oxidant leads to nanometer-scale branching morphologies that have a specific surface area of ~900 m² g⁻¹ with bimodal pore-size distribution.

Ion-conductive and electrochemical properties of solid polymer electrolytes based on poly(ethylene carbonate) (PEC) and magnesium bis(trifluoromethanesulfonyl)imide, Mg(TFSI)₂, with small amount of lithium bis(fluorosulfonyl)imide, LiFSI were investigated. The addition of LiFSI improved the ionic conductivity of PEC-Mg(TFSI)₂, from ~2.3 × 10⁻⁶ S cm⁻¹ to ~1.0 × 10^-5 S cm⁻¹ at 80 °C. Cyclic voltammetry measurements for PEC-based electrolytes revealed that the plating/stripping reaction of Mg/Mg²⁺ is enhanced by the addition of LiFSI.

High-molecular-weight (HM_w) sulfonated polyimide thin films with a semialiphatic main chain exhibited an oriented lamellar structure and high proton conductivity (1.5 × 10^-1 S cm^-1) under humidified conditions. Low-molecular-weight (LM_w) sulfonated polyimide thin films with the same semialiphatic backbone exhibited a nonoriented lamellar structure and low proton conductivity (3.0 × 10^-2 S cm^-1) under humidified conditions. The results indicate that, in sulfonated polyimide thin films with semialiphatic main chain, the lamellar orientation greatly contributes to the high proton conductivity.

We designed elastin-like proteins (ELPs) composed of repetitive VPGIG sequences with or without the RGD cell adhesion motif (ELP-RGD/ELP-Ctrl) and used tetrakis(hydroxymethyl)phosphonium chloride (THPC) as a chemical crosslinker to generate hydrogels. The ELP-RGD and ELP-Ctrl gels were used as substrates for cardiac differentiation culture of murine induced pluripotent stem cells (iPSC). Cells on the ELP-RGD gel showed four times higher expression of the contractile protein gene, troponin T type 2 (TnT2), than those on a collagen type I gel, which is an effective substrate for iPSC cardiac differentiation.

Carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures were synthesized by the self-condensations of aromatic dicarboxylic anhydrides. A linear poly(arylene ether ketone) was obtained from an AB monomer, 4-phenoxyphthalic anhydride, while a hyperbranched poly(arylene ether ketone) was obtained using an AB₂ monomer, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride. The method for the synthesis of the hyperbranched poly(arylene ether ketone) is notable because it provides a high ion-exchange capacity, above 7 mmol g⁻¹, through a one-pot polycondensation.