Articles in 2023

Polyamide (PA) is a potential candidate for seals or barriers in systems used to supply high-pressure hydrogen gas to fuel cell vehicles. The elasticity of the crystalline lattice of PA6 and PA11 was investigated using a WAXD method and a high-pressure cell while applying hydraulic pressures up to 100 MPa. A linear decrease in the d-spacing for the (002) plane (PA6) and the (010) plane (PA11) followed by rapid recovery to the initial value after depressurization was observed as the pressure increased.

Hydroxy-tethered platinum(II) complexes were synthesized and used as diol monomers for polyurethane synthesis. Polyurethanes with moderate molecular weights were obtained by conventional polyaddition with a diisocyanate. The polyurethane containing the platinum(II) complex substituted with t-Bu groups was soluble in common organic solvents, including CHCl₃ and tetrahydrofuran. The obtained polyurethane exhibited distinguishable photoluminescence changes upon grinding in the solid state.

We propose a simple method to detect depth information of ink components and pigment distribution observed by transmission electron microscopy on commercially available cosmetic contact lenses using multiple probes such as STEM EDS, XPS, HAXPES, and XAFS. These provide important information on the safety of cosmetic contact lenses, which are medical devices.

Functional polymers such as semiconducting polymers and polyelectrolytes are essential materials for various polymer thin-film devices. Here we discuss the relationship among the aggregation states, the thermal molecular motion, the carrier properties of their thin films, and the interfacial effects.

Strain-promoted azide-alkyne cycloaddition provides a facile and efficient approach for the modular construction of main-chain polymers comprised of nanosized building blocks.

The flow-induced crystallization behavior of high-density polyethylene (HDPE) was investigated using Rheo-Raman spectroscopy. Although crystallization did not progress at 128 °C without shear flow, the formation of short and long consecutive trans chains was enhanced by applying shear flow, which resulted in an increased crystallization rate. In particular, by increasing the shear rate or shear-flow time, the fraction of long consecutive trans chains drastically increased prior to crystallization, and oriented crystals formed. These results indicated that the shear rate and applied work were the important parameters dominating the formation of oriented crystals.

The aqueous solution of hyperbranched poly(bis-acrylamide)s (HPEAMs) prepared by reversible addition-fragmentation chain-transfer (RAFT) polymerization are of lower critical solution temperature (LCST), which also can response to HCO₃^-. The structure of HPEAM is characterized by the presence of carboxyl groups, thioester groups, and diamine bisacrylamide structural units. The study will reveal how they act in solution to cause these phenomena.

The relationships between the physical parameters of β–cyclodextrin-based nanoparticles (CDNPs), the behavior of α-mangostin release, and the anticancer efficacy were revealed in this study. It was found that the lifetime of complex (τ₂) in slow-release mode was linearly dependent on the nanoparticle density and showed a relationship with anticancer efficacy. We assumed that MGS released from CDNPs would accumulate in the tumor region if the optimal range of τ₂ was approximately 90 to 140 h. These results suggest τ₂ can be a critical quality attribute for designing our CDNPs.

Poly(silane arylether arylacetylene) (PSEA) resins with acetylene groups at different substituted positions were synthesized and the effects of the substituted positions of acetylene groups on the properties of PSEA resins were investigated. The resins possess a wide processing window. The cured resins display high mechanical properties and thermal stability. mmm-PSEA-C possesses better mechanical properties than pmp-PSEA-C. The decomposition temperatures of pmp-PSEA-C and mmm-PSEA-C are over 530 °C.

In this research, we reported a novel and simple approach to using tetramethylthiuram disulfide (TMTD) to prepare self-healing vulcanized natural rubber. TMTD as a sulfur donor and accelerator was used with different contents, ranging from 1.0 to 3.0 phr, to vulcanize high ammonia natural rubber (HANR). The best self-healing performance, i.e., 50–60% stress recovery and 80–95% strain recovery, was achieved for vulcanized natural rubber samples with 1.5 to 2.0 phr loading of TMTD. This approach discovered the potential application of TMTD in preparing self-healing vulcanized natural rubber.

The decomposition process of polystyrene particles dispersed in D₂O was analyzed by in situ small-angle neutron scattering under near critical and supercritical conditions. Upon heating in the subcritical state, the particles were swollen by D₂O because of enhanced miscibility between polystyrene and D₂O. In the supercritical state, the particles were completely degraded and formed monomer- or oligomer-rich domains due to phase separation. The findings and utilized techniques provide essential knowledge about the ways to elucidate the structural change of plastics in sub- and supercritical fluids.

We designed multiblock amphiphilic cyclophanes that possess twisted aromatic units with axial chirality. Electronic absorption and emission spectroscopy revealed that these cyclophanes are molecularly dispersed in organic solvents, while they form aggregates in aqueous environments. We also found that under aqueous conditions, the chiral aromatic units within homochiral cyclophanes adopt a more planar conformation compared to their diastereomer, demonstrating the possibility of stereoselective recognition. Furthermore, by comparing the corresponding multiblock amphiphiles that are linear and chiral, we found that the macrocyclic structure might be essential for recognition.

This work presents a simple strategy to prepare 3D printable and tough ionogels that can adjust to arbitrary topography. Inks for direct ink writing were prepared by dispersing cellulose nanocrystals in an aqueous solution of polyvinyl alcohol. After printing, the ink underwent a freeze-thaw process to form soft and stretchable hydrogels. Further reshaping and solvent exchange with deep eutectic solvents led to geometrically complex and tough ionogels for wearable sensors.

Complex formation of pendant lysine residue-containing zwitterionic random copolymer with copper (II). To remove excess copper in the body, a copolymer (P(MPC/LysA)) comprising 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and l-lysinylacrylamide (LysA) was synthesized via controlled radical polymerization. The copolymer exhibited a zwitterionic structure under physiological conditions due to the pH-independent neutral charge of MPC. The LysA residues were found to form a complex with copper (II) ion (Cu²⁺) under neutral-basic conditions, with two pendant l-lysine residues forming a complex with one Cu²⁺ molecule. P(MPC/LysA) has potential for use in removing excess Cu²⁺ in the body by forming water-soluble aggregates with Cu²⁺ at physiological pH.

In this paper, the construction of a hierarchical supramolecular structure comprising reduction-responsive DNA microspheres and semi-artificial glycopeptide-based micro-asters was described. Such a unique hierarchical supramolecular structure was obtained through molecular assembly of three oligonucleotides and a semi-artificial glycopeptide in a single thermal annealing process under aqueous conditions in the presence of Mg²⁺.

Our recent studies on high-performance semiconducting polymers are reviewed. In the first part of this article, the correlations between semiconducting polymer structures and charge transport properties in thin film transistors are described. The second part of this report summarizes our recent results on the near-infrared emission properties of carefully designed semiconducting polymers.

By taking advantage of the green benefits of multi-component reactions, adhesive polymers were designed and synthesized essentially using bio-based compounds as building blocks. Specifically, phenylpropanoids were selected as a green and photo-responsive chemical units. Synthesized bio-based adhesive polymers showed facile adhesion properties against quartz plates and the adhesion behaviors were altered by photo irradiation, probably owing to the [2 + 2] self-cycloaddition of the phenylpropanoid-derived vinyl moieties.

In this Focus Review, we summarize our new strategy to create electroresponsive soft materials using electroresponsive dopants. Dopants can change the property of the LC material only with a minute amount and do not need to have an LC property by itself, allowing a simple molecular design. Based on this new concept, we developed cholesteric displays with rewritable color memory functions and quick color modulation functions. We also utilized this concept to create new columnar LC systems and realized multiresponsive columnar LC materials.

3D printable hydrogel inks were prepared by incorporating carbon nanotubes (CNT) in a low-concentrated, thermoreversible poly(N-acryloyl glycinamide) hydrogel. After adding the photoinitiator and N-acryloyl glycinamide monomer, the printed inks were further crosslinked into strong, elastic hydrogel networks. The hydrogels based on preliminary cell viability experiments are considered for bioscaffold applications.

Radical copolymerization of lithium p-styrenesulfonate (LiSS) was investigated using acrylamide (AAm) as the comonomer in the presence of various salts as additives. The addition of lithium chloride promoted the polymerization reactivity of LiSS, while the addition of lithium bromide and sodium bromide suppressed the copolymerization of LiSS and AAm and completely prevented the spontaneous homopolymerization of AAm. The interactions between lithium cations and functional groups in the monomers and polymers that benefit the copolymerization reactivity is discussed.