Polymer Journal

Imato, Keiichi; Ooyama, Yousuke

doi: 10.1038/s41428-024-00951-4pmid: N/A

Functional dyes exhibit intriguing properties in response to external stimuli related to their optical, electronic, structural, and energetic characteristics and enable unique stimuli-responsive functions in materials by collaborating with polymers, particularly when chemically incorporated into the polymer structures. As well as the structures and properties of functional dyes, polymers, assemblies, and materials, the interactions between these components are important to the functions of materials. In this review, we introduce our recent studies conducted in the past half decade on stimuli-responsive smart polymers and polymeric materials based on functional dyes that are chemically incorporated into the polymer structures, with a special focus on light, force, electric fields, and chemicals including water in a variety of external stimuli. For example, these polymers and materials offer switchable adhesion, mechanical actuation, and chemical sensing.

Ohyama, Masatoshi; Yasuda, Rie; Miyauchi, Shinsuke; Kohsaka, Yasuhiro

doi: 10.1038/s41428-024-00939-0pmid: N/A

Although vinyl ketones (VKs) exhibit excellent reactivity toward radicals and nucleophiles, their application in polymer chemistry has been limited compared with that of acrylates. One of the reasons is the difficulty of the synthesis, particularly that of multivalent VKs. Herein, we report the facile synthesis of divalent VKs via Friedel‒Crafts acylation of fluorene and subsequent elimination reactions. For example, via this approach, 2,7-diacryloyl-9,9-dimethylfluorene was obtained at high yields (78%). Because the monomer was obtained at high purity through recrystallization and washing, the procedure is suitable for industrial applications. The addition of dithiols and diamines via thia- and aza-Michael addition afforded the corresponding polythioesters and polyamines, respectively. In addition, the divalent VKs exhibited high reactivity in the Morita‒Baylis‒Hillman reaction with formaldehyde, affording a diol monomer. The polycondensation of the diol monomer and isophthaloyl dichloride yielded a poly(conjugated-ketone ester). Consequently, the divalent VKs described herein are attractive monomers and monomer precursors with ready accessibility and sufficient electrophilicity.

Kurioka, Tomoyuki; Tomita, Ikuyoshi; Inagi, Shinsuke

doi: 10.1038/s41428-024-00958-xpmid: N/A

Fluorene (Fl) derivatives are representative emitting motifs; thus, they are often installed into alternating π-conjugated copolymers (P(Fl-Ar)) as soluble polymeric emitters. Many researchers have focused on modifying the combined arylene units in P(Fl-Ar) derivatives to tune their optoelectronic properties; however, P(Fl-Ar) derivatives that contain fluorene units with functional groups at their sp2 carbons remain limited. Here, we synthesize P(Fl-Ar) derivatives comprising sp2-chlorinated fluorene units via anodic chlorination using aluminum chloride (AlCl3). The introduced chlorine atoms affect the optoelectronic properties of the pristine P(Fl-Ar) derivatives. Compared with the precursor P(Fl-Ar) derivatives, chlorinated P(Fl-Ar) derivatives exhibit longer maximum emission wavelengths.

Hayashi, Misato; Takahashi, Rintaro; Vu, Thi Ngan; Matsumura, Kazuaki; Yamago, Shigeru; Yusa, Shin-ichi

doi: 10.1038/s41428-024-00952-3pmid: N/A

This study prepared dual thermoresponsive diblock copolymers (E95Nn; n = 93 and 291) comprising poly(ethylene glycol) ethyl ether acrylate (PeDEGA; E) and poly(N-isopropylacrylamide) (PNIPAM; N) blocks with different lower critical solution temperatures (LCSTs). E95Nn was prepared via organotellurium-mediated living radical polymerization through a one-pot synthesis method. Energy-dispersive X-ray spectroscopy revealed that tellurium residue at the polymer chain end was removed during purification via dialysis. The LCST of the PeDEGA was lower than that of PNIPAM. At temperatures below the LCST of PeDEGA, E95Nn dissolved as a single polymer chain (the unimer state). When an aqueous solution of E95Nn was heated, polymer micelles with a PeDEGA core and PNIPAM shells formed above the LCST of the PeDEGA. In pure water, 7–10 polymer micelles formed intermicellar aggregates. The polymer micelles encapsulated hydrophobic guest molecules into the hydrophobic core formed from the PeDEGA chains. Large intermicellar aggregates formed above the LCST of PNIPAM owing to hydrophobic interactions between the PNIPAM shells. It is expected that E95Nn polymer micelles can be applied as drug carriers for thermoresponsive controlled drug release.

Nazmul Islam, A. B. M.; Kayo, Nana; Motoishi, Yuki; Hamano, Ryo; Tanaka, Naoki; Kato, Koichiro; Fujigaya, Tsuyohiko

doi: 10.1038/s41428-024-00950-5pmid: N/A

The surface modification of carbon materials is an effective method for enhancing the properties of carbon-based functional materials; particularly, the use of a polymer coating is advantageous owing to its intactness and simplicity. Polybenzimidazole (PBI) has been used to modify carbon surfaces, yet its adsorption behavior has not been thoroughly examined. In this study, the adsorption kinetics and thermodynamics of PBI adsorption on various types of carbon black with different surface morphologies and chemical compositions were analyzed via isotherm measurements. To determine the effects of the polymer, its adsorption behavior was compared to that of the PBI monomer (1,3-bis(1H-benzo[d]imidazol-2-yl)benzene (referred to as the PBI-unit)). The surface adsorption of PBI was slower than that of the PBI-unit; however, PBI exhibited a greater adsorption capacity. The PBI adsorption is an entropy-driven process, whereas PBI-unit adsorption is enthalpy-driven. The adsorption of PBI was more thermodynamically favorable on carbon surfaces with higher crystallinity (lower oxygenation) owing to the easier detachment of solvent molecules from the carbon surface, leading to a higher adsorption constant.

Liu, Zitong; Karasawa, Takumi; Tan, Wei; Minegishi, Hikaru; Matsushita, Yasuyuki; Shikinaka, Kazuhiro; Otsuka, Yuichiro; Tominaga, Yoichi

doi: 10.1038/s41428-024-00941-6pmid: N/A

Lignin is the most abundant aromatic material in the Earth’s terrestrial ecosystems. However, very few studies have been conducted on the potential application of lignin derivatives as fillers for electrolytes in lithium batteries to determine cell performance. Herein, a novel electrochemically stable composite polymer electrolyte (CPE) containing a lignin derivative and dilignol was exploited for battery application for the first time. The lignin derivatives improved both the ionic conductivity and mechanical performance of the polymer-based electrolytes. The resulting alterations in the coordination number led to enhanced Li+ mobility and consequently, increased conductivity. Notably, the LiFePO4/Li cell had good stability and recovery capacity, and the Coulombic efficiency was approximately 100%, with a capacity of more than 150 mAh g−1.

Yoshida, Takumi; Hoshi, Toru; Aoyagi, Takao

doi: 10.1038/s41428-024-00948-zpmid: N/A

In this study, polymers with different copolymerization composition ratios of α-chloro-ε-caprolactone (α-ClCL) and ε-caprolactone (ε-CL) were prepared using α-ClCL, which can polymerize on its own. The copolymers were prepared by using trimethylolpropane as the initiator, and acryloyl groups were added to the polymer ends to form macromonomers capable of cross-linking reactions. The functionalized macromonomers were confirmed to possess shape-memory properties when cross-flinked in film form by heat. The composition of the functional groups in the macromonomer could be adjusted by changing the ratio of α-ClCL to ε-CL used in the copolymerization. In addition, the chloro group introduced by α-ClCL was converted into an azide group. Both the cross-linked film with chloro groups and the film converted to azide groups prepared in this study exhibited shape-memory according to the softening point of the film. Through fluorescence microscopy, it was confirmed that the converted azide groups were modified with alkylated rhodamine B based on the click reaction. Furthermore, azide-assisted films are expected to add various functions through click reactions in the future.

Murasawa, Yoshihiro; Yoshii, Tomoya; Suzuki, Takumi; Shimomura, Takeshi

doi: 10.1038/s41428-024-00949-ypmid: N/A

An ionic electroactive polymer actuator (IEPA) was fabricated in this study using a blend of regioregular-poly(3-hexylthiophene) (RR-P3HT) nanofibers, regiorandom-P3HT (RRa-P3HT), and polybutadiene rubber (PBR). The RR-P3HT nanofiber mat, which was reinforced with RRa-P3HT as tie chains and PBR as a flexible matrix, exhibited a large surface area where the nanofibers contacted the electrolyte. Therefore, efficient actuation is expected to synergize with the superior carrier mobility inherent in the nanofibrous architecture. The blended actuator, which preserved the RR-P3HT nanofiber structure, exhibited a substantial bending angle exceeding 80° following the redox reaction while sustaining reversible actuation for more than 30 cycles. An optimal scan rate below 100 mV s−1 was required to obtain substantial actuation. Therefore, the RR-P3HT nanofibers blended with RRa-P3HT and PBR demonstrated remarkable functionality as an IEPA, which was characterized by a significant bending angle and enduring cyclic actuation capabilities.

Liu, Yalei; Chang, Junfang; Guo, Zhiyong; Wang, Sui; Mao, Jie

doi: 10.1038/s41428-024-00957-ypmid: N/A

Multifunctional hydrogel materials are being increasingly used in wearable sensing devices and biomedical applications, but the comprehensive performance of hydrogel materials must be further developed. To prepare hydrogels with better self-healing properties, biomacromolecules such as sodium alginate and carboxymethyl chitosan were used as raw materials by combining the dynamic imine bonding network formed by both materials with the coordination bonding network formed by acrylic acid and aluminum ions. The double network structure of the hydrogel provides the hydrogel with excellent self-healing properties (up to 127% recovery of toughness after self-healing) and good mechanical properties with a fracture strain of 3787%. Substances with antimicrobial properties in the hydrogel network inhibited the growth of E. coli and S. aureus. In addition, the hydrogel has good electrical conductivity with a conductivity of 1.41 S/m. This study examined multiple properties of the hydrogel and provides a reference for the application of this material in practical application scenarios.

Iwakiri, Toma; Suzuki, Hikari; Mastubara, Shogo; Higuchi, Masahiro

doi: 10.1038/s41428-024-00960-3pmid: N/A

We fabricated a volatile organic compound (VOC) sensor with a peptide–Au nanoparticle (AuNP)–TiO2 nanocomposite in which AuNPs were linked with TiO2-coated conductive peptide nanowires. The conductive peptide nanowires were formed between the AuNPs via self-assembly through the complexation of amphiphilic peptides, LESEHEKLKSKHKSKLKEHESEL, and Co(II). Furthermore, TiO2 mineralization on the surface of the peptide nanowires yielded mixed crystals of rutile and anatase, which exhibited highly effective photolytic activity. In particular, the obtained TiO2 exhibited three times greater photodecomposition activity in the unsintered state toward organic matter than did commercially available TiO2. Next, we constructed a VOC sensor by immobilizing peptide–AuNP–TiO2 nanocomposites on a comb electrode. The electrochemical properties of the nanocomposite changed drastically under light irradiation in the presence of VOCs, indicating transport of the VOC-decomposition-generated photoexcited electrons of TiO2 to AuNPs through conductive peptide nanowires, which prevented electron–hole recombination. The obtained sensor exhibited a sensing range of 2–100 ppm for dichloromethane, which was used as a representative VOC. Therefore, nanocomposites made of AuNPs linked with conductive TiO2 nanotubes may be highly effective for TiO2-driven VOC decomposition. Moreover, we believe that this nanocomposite has high sensitivity for sensing VOCs.