Original Article in 2023

Double-hydrophilic block copolymers composed of a water-soluble poly(carboxybetaine acrylate) and a water-insoluble poly(2-methoxyethyl acrylate) (PCBA2_n-b-PMEA_m) produced particles in dilute aqueous solutions and microphase-separated structures in concentrated aqueous solutions. The microphase-separated structures were associated with the volume fraction and molecular weight-dependent water solubility of the PMEA chain. The morphology of the microphase-separated structure was independent of the polymer concentration, probably because the block copolymer aggregates were isolated as coacervates. The morphology was tolerant to NaCl concentration due to the nonelectrostatic aggregation of PMEA.

Postfunctionalization of poly(vinyl alcohol) (PVA) was performed in supercritical carbon dioxide (sc-CO₂) for the selective functionalization of the amorphous region. The crystalline region was retained in the amorphous-selective acetylated PVA. The oriented structure of crystallites of the drawn PVA was maintained even after acetylation in sc-CO₂. Moisture adsorption behaviors affected the crystalline structure of PVA acetylated in sc-CO₂. The PVA acetylated in sc-CO₂ included a larger number of water molecules under humid conditions, but the increase in thickness after water adsorption was smaller than that of randomly acetylated PVA.

Using temperature variable SAXS and WAXS techniques, nature of thermal expansion behavior of injection molded iPP was investigated. The SAXS and WAXS provided the thermal expansion in amorphous phase and the one in crystal axes, respectively. The bulk thermal expansion was fully accounted for by the combination of them. It was found that the thermal expansion from the amorphous phase contributed significantly to the bulk thermal expansion.

Iron-modified catechol hydrogel treatment with EDTA is investigated at three immersion pH levels – pH 3, 5, and 7. The introduction of EDTA facilitates the chelation of Fe³⁺ ions, resulting in a modified hydrogel with enhanced metal ion binding capacity. The functionalized catechol chitosan hydrogel after the treatment exhibits potential applications in biomedical and environmental fields. This research sheds light on the development of versatile hydrogel materials with tailored properties, showcasing the capabilities in diverse applications where metal ion interactions play a crucial role.

Coordination polymerization of a series of 2-substituted-[3]dendralenes was investigated. No polymerization was observed for 2-trimethylsilyl[3]dendralene, whereas 2-phenyl[3]dendralene polymerized by CpTiCl₃ as a catalyst and modified methylaluminoxane as an auxiliary catalyst to generate polymers that became insoluble in the process of isolation. Additionally, the coordination polymerization of 2-hexyl[3]dendralene was conducted using a CpTiCl₃/modified methylaluminoxane catalyst to produce polymer with mainly a trans-4,6 structure, which differs from that of the polymer obtained via anionic polymerization. The copolymerization of isoprene with 2-hexyl[3]dendralene was also examined.

Polymer composites containing citric acid-modified cellulose (CAC) and hydrogen bonding moieties showed significant increases in mechanical toughness. In particular, an appropriate ratio of hydrogen bond donors and acceptors in the secondary linear polymer (poly(2-methoxyethyl acrylate)) maximized the toughness. The hydrogen bonds affected the phase. The maximum toughness was achieved for an amorphous structure without obvious phase separation.

Polymers that can depolymerize into their constituent monomers are desirable sustainable materials, but demonstrations have focused on linear polymers. Here, a depolymerizable graft copolymer thermoplastic material is prepared by copolymerizing poly(L-lactide)-based and margaric acid-based trans-cyclobutane-fused trans-cyclooctene macromonomers. The two types of macromonomers are incorporated randomly. Proper thermal treatment is required to maximize, or even to observe, crystallinity in the microphase separated that persists over a range of temperature. The physical states of the soft and hard domains significantly impact the material’s tensile properties.

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.

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.

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.

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.

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.

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.