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We have developed innovative new phosgenation reactions and their special reaction systems with the key objective of “safe application” to organic synthesis. This focus review summarizes our recent studies on in situ photo-on-demand phosgenation reactions of alcohols and amines for synthesizing polycarbonates, polyurethanes, and their precursors such as chloroformates, carbonate esters, and diisocyanates, in batch reaction systems, which are preferable for laboratory or small-scale industrial syntheses.
Atomic force microscopy (AFM)-based nanomechanical characterization techniques have been extensively used to investigate the mechanical properties and 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 article discusses the application of this technique to studying polymer composites with a specific focus on the significant advances made in tracking the microscopic deformation behavior and visualizing the microscopic stress distribution of materials.
The recent studies on the development of polymeric core crosslinked particles for drug delivery system are reviewed. The first part of this article describes synthesis of polymeric core crosslinked particles via the formation of nanoemulsion, characterization of the particle structure using small angle scattering techniques, and effect of polymer chain conformation on the particle pharmacokinetics and pharmacodynamics. The second part introduces zwitterionic amino acid polymer (ZAP)-based core crosslinked particles and discusses some advantages of using ZAPs as a pilot macromolecule for cancer-targeting chemotherapy.
Anionic initiator systems for styrene polymerization were prepared via desilylation of benzylsilanes with metal alkoxides. Benzyltrimethylsilyl anions as the anionic polymerization initiators were obtained from benzylsilanes and potassium tert-butoxide at 70 °C in the absence of 18-crown-6. On the other hand, in the presence of 18-crown-6, benzyl anions were obtained at −78 °C. Subsequent addition of the styrene monomer to these initiators yielded polystyrenes. With the addition of 1,1-diphenylethylene (DPE) to the initiator system containing 18-crown-6, the corresponding DPE adduct was obtained.
Polymer gels containing an iridium complex in their compartmentalized nanodomain structures were designed. Novel Ir-containing vinyl monomers were first synthesized and then incorporated into homogeneously dispersed thermoresponsive nanodomains via living radical polymerization. The product gels exhibited immediate color change by sensing ammonia in a thermoresponsive manner, and catalyzed the N-alkylation reaction. These findings strongly supported the importance of the incorporation of organometallic complexes into the nanodomain of hydrogels for the further development of a novel soft material exhibiting selective molecular recognition abilities and catalytic reactions.
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 by size-exclusion chromatography with a multiangle light scattering (SEC-MALS) and atomic force microscopy (AFM). Our results provided experimental proof that the desired sheet-like polymer was attained and the obtained samples were appropriately characterized, augmenting the previous reports.
Statistical structural analysis was conducted for ternary blends of copolymers composed of two monomers chosen from acrylonitrile, α-methylstyrene, and styrene. Blending parameters, such as the composition and blending fraction of the component copolymer, were predicted by regularized regression analysis of 1H NMR data. Regression models were constructed with the dataset for copolymers and binary blends to predict the blending parameters for ternary blends. The composition and blending fraction were predicted with high accuracies
The transparent and flexible photocatalytic films composed of titanium oxide, organophosphonate-modified polysilsesquioxane, and poly(bisphenol A-co-epichlorohydrin) were prepared. The effects of hydroxy group ratio and organic substituent on phosphorus atoms in these films were evaluated by appearance and photocatalytic ability. Film using anchoring layer with APPS-low was formed large cracks, while films with other anchoring layers were formed no cracks. However, all films were formed small cracks after a 10-day durability test. All films showed photodegradation ability of methylene blue, photoinduced hydrophilicity, and photocatalytic bactericidal effects on Escherichia coli.
A novel polymer material PEDOT:DBSA was prepared using oxidative polymerization and was modified by cross-linker GOPS and H2SO4-posttreatment. This material exhibits biocompatibility toward cell culture comparable to the glass substrate. The cross-linking process resulted in complete stabilization of PEDOT:DBSA thin film in an aqueous environment, whereas such stabilization was achieved even without high-temperature treatment. The model OECT device proved that the proposed material possesses electrical properties comparable to or even better than other organic mixed conductors used for transistors. This all shows a great potential of PEDOT:DBSA for bioelectronics applications.
We propose a method for analyzing the morphology of polymer blends with nanometric resolution using scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopic imaging in the low energy-loss region (5–30 eV). Furthermore, we employed medium-voltage (200 kV) and high-voltage (1000 kV) STEMs at different temperatures to compare the extent of electron-beam damage. This comparison highlighted the utility of the ultra-high voltage electron microscope for suppressing thermal damage and analyzing thicker samples.
