Polymer Journal

Tsuda, Akihiko

doi: 10.1038/s41428-023-00800-wpmid: N/A

Phosgene is an important carbonyl source for industrial production of polycarbonates (PCs) and polyurethanes (PUs). However, since it is highly toxic, alternative compounds and/or new phosgenation reactions have been explored for safety reasons. Given this background, we found a novel photochemical reaction enabling the synthesis of phosgene from chloroform. Subsequently, we developed new phosgenation reactions and reaction systems, and the key objective was “safe application” to organic synthesis. This focus review reports our recent use of in situ photo-on-demand phosgenations of alcohols and amines in synthesizing PC, PU, and their precursors, such as chloroformates, carbonate esters, and diisocyanates, in batch reaction systems, which are preferable for laboratory or small-scale industrial syntheses. We believe that the present reactions have advantages over conventional phosgenation reactions, especially in terms of safety and environmental impacts, and are expected to make positive contributions to practical organic syntheses in both academia and industry.

Liang, Xiaobin

doi: 10.1038/s41428-023-00790-9pmid: N/A

Atomic force microscopy (AFM) is considered an advanced tool for microscopic study of materials study due to its capabilities for nanoscale spatial characterization. Over the past two decades, the AFM-based nanomechanical characterization technique has been extensively used to investigate the mechanical properties and deformation mechanisms of polymeric materials. This technique enables direct visualization of the micromechanical properties of material surfaces and is referred to as the AFM nanomechanics technique. This review discusses the application of this technique in the study of polymer composites with a specific focus on the significant advances made in tracking the microscopic deformation behavior and visualizing the microscopic stress distributions of materials.

Fujii, Shota

doi: 10.1038/s41428-023-00793-6pmid: 37359987

Various polymeric nanoparticles have been used as drug carriers in drug delivery systems (DDSs). Most of them were constructed from dynamic self-assembly systems formed via hydrophobic interactions and from structures that are unstable in an in vivo environment owing to their relatively weak formation forces. As a solution to this issue, physically stabilized core-crosslinked particles (CP) with chemically crosslinked cores have received attention as alternatives to the dynamic nanoparticles. This focused review summarizes recent advances in the construction, structural characterization, and in vivo behavior of polymeric CPs. First, we introduce a nanoemulsion-mediated method to create polyethylene glycol (PEG)-bearing CPs and their structural characterization. The relationship between the PEG chain conformations in the particle shell and the in vivo fate of the CPs is also discussed. After that, the development and advantages of zwitterionic amino acid-based polymer (ZAP)-bearing CPs are presented to address the poor penetration and the internalization of PEG-based CPs into tumor tissues and cells, respectively. Finally, we conclude and discuss prospects for application of polymeric CPs in the DDS field.

Terasaki, Masaya; Hiraki, Yujiro; Adachi, Kaoru

doi: 10.1038/s41428-023-00791-8pmid: N/A

Anionic initiator systems for styrene polymerization were prepared via desilylation of benzylsilanes with metal alkoxides. The anionic polymerization initiators were obtained from benzylsilanes and potassium tert-butoxide at 70 °C. On the other hand, in the presence of 18-crown-6, the initiators were obtained at −78 °C. Subsequent addition of the styrene monomer to these initiators yielded polystyrenes. A 1H NMR analysis of the resulting polymers suggested that benzyltrimethylsilyl anions were obtained at the elevated temperature in the absence of 18-crown-6, whereas benzyl anions were obtained at the low temperature in the presence of 18-crown-6. With the addition of 1,1-diphenylethylene (DPE) to the initiator system containing 18-crown-6, the corresponding DPE adduct was obtained. These results indicated that the benzyl anions served as anionic polymerization initiators and were generated by desilylation.

Furukawa, Shohichi; Okuno, Takahiro; Shimbayashi, Takuya; Takeshita, Hiroki; Fujita, Ken-ichi; Ida, Shohei

doi: 10.1038/s41428-023-00801-9pmid: N/A

Incorporating organometallic complexes into nanodomains in polymer networks would broaden the scopes of gel material design and applicability. In this study, we designed polymer gels containing an iridium complex in the crosslinked domain (CD) of their compartmentalized nanodomain structures and demonstrated their molecular sensing ability and catalytic activity levels. Novel Ir-containing vinyl monomers were first synthesized and then incorporated into a thermoresponsive CD structure by reversible addition–fragmentation chain-transfer polymerization using a hydrophilic bifunctional macro-chain transfer agent with N-isopropylacrylamide and a crosslinker. A model reaction and structural analysis revealed that the product gel exhibited a homogeneously dispersed CD structure containing an Ir complex. The Ir-containing gel immediately changed color by sensing ammonia in a thermoresponsive manner and catalyzed the N-alkylation reaction.

Doi, Yuya; Hara, Mitsuo; Seki, Takahiro; Takano, Atsushi; Ishida, Takato; Uneyama, Takashi; Masubuchi, Yuichi

doi: 10.1038/s41428-023-00795-4pmid: N/A

Two-dimensional sheet-shaped poly(methyl methacrylate) (2d-PMMA) with crosslinking only in the two-dimensional direction was synthesized via planar polymerization of MMA monomer in montmorillonite (MMT) nanolayers by using γ-ray irradiation, and the samples obtained were characterized. Size-exclusion chromatography with a multi-angle light scattering (SEC-MALS) measurements of the obtained sample showed bimodal peaks: a main peak with a longer elution time and an apparent molecular weight Mw,app and radius of gyration Rg in tetrahydrofuran (THF) similar to those for linear PMMA samples, and a subpeak with a shorter elution time and Mw,app and Rg evidently lower than those for the linear PMMA samples. This result indicated that polymers with moderate branching and crosslinking were contained in the subpeak. Atomic force microscopy (AFM) observation of the sample showed the presence of sheet-shaped molecules with a height of ca. 0.6 nm, corresponding to the thickness of one MMA monomer, and a width of several to several tens of nanometers, showing a broad distribution in molecular width. The subpeak portion was isolated via SEC fractionation, and its AFM observation showed thin circular disk-shaped molecules with relatively uniform size (i.e., a width of several tens of nanometers). However, in these molecules, two types of molecular heights (i.e., 0.6 and 1.2 nm) were identified. This result indicated that MMA monomers were filled as two layers within one MMT interlayer, and the polymerization reaction proceeded in that state. The similarity in the molecular size of 2d-PMMA observed via AFM and SEC-MALS was confirmed. These results demonstrated that the desired sheet-shaped polymers were obtained through the above synthesis and fractionation process.

Kamiike, Ryota; Hirano, Tomohiro; Ute, Koichi

doi: 10.1038/s41428-023-00794-5pmid: N/A

Statistical 1H nuclear magnetic resonance (NMR) analyses were conducted with ternary copolymer blends. Two out of the three monomers, acrylonitrile, styrene, and α-methylstyrene, were subjected to radical copolymerization to synthesize three kinds of copolymers that were mixed to prepare binary and ternary copolymer blends. The 1H NMR spectral matrix for the copolymers and their blends (explanatory variables) was combined with the blending parameter matrix (objective variables). Cross-validation with the least absolute shrinkage and selection operator regression confirmed that excellent regression models were constructed with a dataset composed of data for eight copolymers and forty-five binary blends; these were used to predict the blending parameters for the binary blends, such as the chemical compositions and mole fractions of the component copolymers. Accordingly, the models were then used to predict the blending parameters for the ternary blends, which resulted in successful and highly accurate predictions. Other regularized regression models, such as Ridge regression and Elastic Net, were also examined.

Kajiyama, Miyu; Sato, Yohei; Okada, Takumi; Motomura, Haruka; Ando, Shiro; Suzuki, Tomonori; Yamamoto, Kazuki; Hayami, Ryohei; Gunji, Takahiro

doi: 10.1038/s41428-023-00796-3pmid: N/A

Transparent and flexible photocatalytic films have attracted considerable attention in recent years. We previously prepared a film with titanium dioxide (TiO2) and an anchor layer of phenylphosphonate-modified polysilsesquioxane (PhPPS-low), which had a phosphonate group and a phenyl substituent; this film exhibited transparency and flexibility. In this study, we reported the differences in the hydroxy group ratio on the phosphorous atoms and the presence or absence of phenylene moieties. Three organophosphonate-modified polysilsesquioxanes (APPS-low, APPS-high, and PhPPS-high) were synthesized. All photocatalytic films using APPS-high, APPS-low, and PhPPS-high exhibited photodegradation of methylene blue and photocatalytic bactericidal effects on Escherichia coli, and hydroxyl radical generation was confirmed. In particular, the photocatalytic film with PhPPS-high showed the highest photocatalytic ability.

Tumová, Šárka; Malečková, Romana; Kubáč, Lubomír; Akrman, Jiří; Enev, Vojtěch; Kalina, Lukáš; Vojtková, Eva; Pešková, Michaela; Víteček, Jan; Vala, Martin; Weiter, Martin

doi: 10.1038/s41428-023-00784-7pmid: N/A

In this work, a novel conductive polymer composite consisting of poly(3,4-ethylenedioxythiophene) doped with dodecylbenzenesulfonic acid (PEDOT:DBSA) for bioelectronic applications was prepared and optimized. The novel PEDOT:DBSA composite possesses superior biocompatibility toward cell culture and electrical characteristics comparable to the widely used PEDOT:PSS. The cross-linking processes induced by the cross-linker glycidoxypropyltrimethoxysilane (GOPS), which was investigated in detail using Fourier transform Raman spectroscopy and XPS analysis, lead to the excellent long-term stability of PEDOT:DBSA thin films in aqueous solutions, even without treatment at high temperature. The electrical characteristics of PEDOT:DBSA thin films with respect to the level of cross-linking were studied in detail. The conductivity of thin films was significantly improved using sulfuric acid posttreatment. A model transistor device based on PEDOT:DBSA shows typical transistor behavior and suitable electrical properties comparable or superior to those of available conductive polymers in bioelectronics, such as PEDOT:PSS. Based on these properties, the newly developed material is well suited for bioelectronic applications that require long-term contact with living organisms, such as wearable or implantable bioelectronics.

Umemoto, Hiroki; Arai, Shigeo; Otobe, Hirohide; Muto, Shunsuke

doi: 10.1038/s41428-023-00786-5pmid: N/A

Polymer blends composed of multiple types of polymers are used for various industrial applications; therefore, their morphologies must be understood to predict and improve their physical properties. Herein, we propose a spectral imaging method based on scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy to map polymer morphologies with nanometric resolution as an alternative to the conventional electron staining technique. In particular, the low-loss spectra of the 5–30 eV energy-loss region were measured to minimize electron irradiation damage rather than the core-loss spectra, such as carbon K-shell absorption spectra, which require significantly longer recording times. Medium-voltage (200 kV) and high-voltage (1000 kV) STEM was used at various temperatures to compare the degrees of electron-beam damage resulting from various electron energies and sample temperatures. A multivariate curve resolution technique was used to isolate the constituent spectra and visualize their distributions by distinguishing the characteristic peaks derived from various chemical species. High-voltage STEM was more useful than medium-voltage STEM for analyzing thicker samples while suppressing ionization damage.