Research articles

The birefringent properties of poly(phosphonate)s and poly(thiophosphonate)s possessing various bisphenol structures were investigated. The C_R values (orientational birefringence) of the poly(phosphonate)s and the poly(thiophosphonate)s range from −0.3 × 10⁻⁹ to + 1.3 × 10⁻⁹ Pa⁻¹ and from −0.6 × 10⁻⁹ to + 0.8 × 10⁻⁹ Pa⁻¹, respectively, which are lower than those of the corresponding bisphenol A-based polymers. The C_D values (photoelastic birefringence), which range from + 4.0 × 10⁻¹¹ to + 4.9 × 10⁻¹¹ Pa⁻¹, are also lower than those of the corresponding bisphenol A-based polymers.

Polar polymers with permanent dipoles such as poly(vinylidene fluoride) (PVDF) are suitable for use as high-energy storage density dielectrics because of their high permittivity. This study investigated the ferroelectricity and energy storage behaviors of PVDF Langmuir–Blodgett (LB) nanofilms at sub-50 nm thicknesses. The ferroelectric hysteresis loops were measured using a Sawyer–Tower circuit in different electric fields. An energy density of 6.0 J/cm³ at 500 MV/m was demonstrated for the 12-nm-thick PVDF LB nanofilm device.

We developed flame-retardant thermoplastics directly from biomass just by dissolution into ionic liquids and precipitation. During the dissolution, a phosphonate-type ionic liquid adducted on the polymers included in biomass such as cellulose through reaction of the hydroxyl groups. In this method, more than 86% of the hydroxy groups were maintained after ionic liquid substitution because the single phosphonate-type ionic liquid acted as a plasticizer and flame retardant in the plant biomass. Therefore, the plant biomass-derived flame-retardant thermoplastics have the potential for further functionalization.

The solid-state structure of L₂AlEt is reported by X-ray diffraction. BnOH (1 equiv. to L₂AlEt) selectively reacts with ~0.5 equiv. of L₂AlEt to afford free L–H (~1 equiv.) while maintaining L₂AlEt (~0.5 equiv.). The stoichiometric balance suggests the formation of 0.5 equiv. of (BnO)₂AlEt. The ROP of CL via the synergic catalysis of the two coexistent Al-complexes, L₂AlEt (0.50 mol%) as a Lewis acid activator of CL and (RO)₂AlEt (0.50 mol%) as a nucleophile, is proposed.

The aqueous oxidative coupling polymerization of 3,4-ethylenedioxythiophene was conducted in the presence of heptadecafluorooctane sulfonic acid, which was used as a perfluoroalkyl dopant to synthesize hydrophobic poly(3,4-ethylenedioxythiophene) particles. The dried poly(3,4-ethylenedioxythiophene) particles could be used as a near-infrared-responsive liquid marble stabilizer exhibiting light-to-heat conversion properties. The movement of the poly(3,4-ethylenedioxythiophene) particle-coated liquid marbles on a planar water surface was driven by near-infrared laser-induced Marangoni propulsion.

The electro-optic properties of polymer-stabilized blue phases (PSBP) with polar chiral dopant and polar substituent on polymer were significantly enhanced, which is in sharp contrast with the trend observed for PSBP with conventional chiral dopant. These results indicate that polar chiral dopant showing good affinity with polar polymer induces weak anchoring condition inside PSBP.

Concentrated poly(ethylene carbonate) (PEC) and poly(trimethylene carbonate) (PTMC) blend electrolytes with 150 mol% of LiFSI were prepared and the PEC₆PTMC₄ electrolyte was applied in all-solid-state Li batteries. The blend electrolyte has an ionic conductivity of 10⁻⁵ S cm⁻¹ and a Li⁺ transference number (t₊) of 0.73. Meanwhile, the PEC₆PTMC₄ electrolyte exhibits a good electrochemical stability with Li electrode than those of PEC and PTMC single-polymer electrolytes. An LFP half-cell exhibits a discharge capacity of 150 mAh g⁻¹ at 50 °C and a C/10 rate.

We described the synthesis of PGA via an azeotropic distillation method that enables tunable molecular weights. This alternative method produces a white powdered PGA rather than a waxy brown product that is obtained by conventional melt-solid condensation methods. Additionally, improved solubility renders this method useful for producing soluble high molecular weight PGA for further applications. Highly crystalline PGA with a high molecular weight (M_n = 32,100 g/mol) was obtained with a homogenous polydispersity index of 1.2–1.4.

The toughness and flame retardancy of glass fiber (GF)-reinforced polycarbonate (PC) composites were tested by adding four impact modifiers and three kinds of flame reardants. Silicon acrylate rubber (SiR) could significantly toughen the composites by 2.52 times. Then only by addition of 0.2 wt% oligomeric siloxane-containing potassium dodecyl diphenylsulfone sulfonate (SiKSS), PC/GF/SiR composites can achieve good flame retardancy with a V0 rating in UL-94 burning vertical test. This formulation also maintained the system a relative high heat deflection temperature around 120 °C.

A novel surface wrinkling system, based on the fabrication of a polyion complex (PIC) skin layer, is introduced. PIC skin layers are fabricated on the surface of chitosan (CS) films via immersion in sodium alginate (AG) solutions. After removal of excess adsorbed AG, microscopic wrinkles appear upon drying. Water resistance in the wrinkled films was achieved by thermal crosslinking of the PIC skin layer. The thermally crosslinked wrinkled surfaces that were composed of covalently crosslinked CS and AG exhibited low cell adhesiveness and are suitable for use in implantable materials.

The deviant and irregular polymerization behavior of 4-acetoxystyrene was found through the detailed study on the ATRP of various para-substituted styrenes bearing electron-withdrawing and electron-donating groups. The relationship between the rate constant for polymerization rate and the Hammett parameter was discussed.

The effect of silica nanoparticle size and concentration on the mechanical strength and wellbore plugging performance of SPAM/ chromium (III) acetate nanocomposite gels was investigated. First, the rheological behavior of gelant, surface chemistry, morphology, and viscoelastic properties of synthesized nanocomposites were investigated. In addition, an experimental setup was designed to determine the maximum differential compressive pressure (DCP) that the synthesized nanocomposite gels can tolerate before failing. The nanocomposites containing 20–30 nm particles have a higher DCP in comparison to those having 7–10 and 60–70 nm nanoparticles.

We optimized the sonoporation of a suspension culture with microbubbles for labeling and MR tracking of mesenchymal stem cells (MSCs). When water was used as the transmission medium between the acoustic probe and cell suspension, microbubbles gently collapsed with minimal cell damage. Under this condition, the number of labeled MSCs was 25%, which is 3.3-fold greater than the number of MSCs labeled using the conventional electroporation system, and the cell viability was maintained at approximately 80%. The MRI signal could be clearly observed for 2.0 × 10⁶ MSCs.

Solution-cast gold-like lustrous films of oligo(3-methoxythiophene) were subjected to benzene exposure and benzene addition treatments. Both treatments provided films with a higher luster and more intense yellowness, i.e., an enhancement in a gold tone. Such a gold-tone-enhancing effect was explained by a model in which upon the treatments, the oligomers adopt a planar conformation through π–π interactions between benzene and the thiophene rings, and the resulting sandwich structures facilitate the formation of edge-on lamellar crystallites, the most likely gold-tone developing structure.

We prepared ionic conductive compound (ICC) by solution casting and the in situ polymerization of poly(ethylene glycol) methyl ether methacrylate (OEGMA) in the presence of PMMA and a cross-linking agent. Then, ionic conductive polymer blends was obtained by melt-mixing ICC and poly(L-lactic acid) (PLLA). We studied the relationship between phase structure and physical properties such as electrical and mechanical properties of the blends.

Microcellular and nanocellular silicone rubber foam are prepared by supercritical carbon dioxide in this work. The t_pre and P_s are important factors which affect the open-cell content (OCC). When the t_pre and P_s increases, the OCC sharply improves and could reach to more than 96%. The OCC has a significant effect on the mechanical properties of the nano/micro silicone rubber foam.

We discover a new cavitation phenomenon in amorphous polymers sandwiched between two thick slide glasses from the static melt induced by thermal treatment. By quenching atactic polystyrene samples from the static melt under the glass transition temperature (T_g) and annealing them above T_g, cavities are created to relax the negative pressure. Cavity growth undergoes an Ostwald ripening-like process in cases of large molecular weight while it undergoes a viscous fingering process in cases of small molecular weight.

N-succinimidyl monomers such as N-methacryloxysuccinimide (MASI) and N-acryloxysuccinimide (ASI) were utilized as prepolymers to synthesize glycopolymers via postpolymerization modification. Living radical polymerization with RAFT agents succeeded using not only MASI but also ASI. While the polymerization with ATRP initiator did not succeed using ASI, the procedure was successful with MASI. MASI was also applicable for SI-ATRP reactions on substrate surfaces. The introduction rate of NH₂-terminated saccharide onto the prepolymer via amine coupling reaction was affected by the reaction temperature. This preparation procedure via postpolymerization modification is expected to provide a facile method for various functional polymers, such as other saccharide and beneficial ligands.

The reactive groups (–OH or –NH₂) of natural melanin nanoparticles from cuttlefishes react with isocyanate groups in pre-polyurethane (pre-PU) to form cross-links, further strengthening the self-healing of PU based on the reversible acylhydrazone bond. The self-healing efficiency was improved from 91.73% to 99.58% due to the strong interactions between the MNs and PU.

The chain dynamics in a spin-coated poly(methyl methacrylate) (PMMA) film in solvent annealing was studied by in situ neutron reflectivity. The absorbed solvent molecules homogeneously distributed in the spin-coated film and the PMMA chain even near the substrate showed sufficient mobility in the solvent annealing process, while the chain mobility was strongly restricted at the substrate in thermal annealing. This result indicates that the solvent annealing method enables the equilibration of a spin-coated polymer film from the surface to the substrate interface.