Synthesis of water‐dispersible,fluorinated particles with grafting sulfonate chains by the core crosslinking of block copolymer micelles

Fluorinated polymer particles with grafting sulfonate chains, which showed high dispersion stability in aqueous media, were synthesized by the crosslinking of block copolymer micelles. A crosslinkable block copolymer, poly[(2,3,4,5,6‐pentafluorostyrene)‐co‐4‐(1‐methylsilacyclobutyl)styrene]‐b‐poly(neopentyl 4‐styrenesulfonate), composed of a statistical copolymer segment of 2,3,4,5,6‐pentafluorostyrene with 4‐(1‐methylsilacyclobutyl)styrene and a neopentyl 4‐styrenesulfonate segment, was prepared by the nitroxy‐mediated living radical polymerization of a 2,3,4,5,6‐pentafluorostyrene/4‐(1‐methylsilacyclobutyl)styrene mixture and neopentyl 4‐styrenesulfonate. The block copolymer formed micelles with a poly[(2,3,4,5,6‐pentafluorostyrene)‐co‐4‐(1‐methylsilacyclobutyl)styrene] core in acetonitrile, which were crosslinked via the ring‐opening reaction of silacyclobutyl groups in the core by a treatment with a platinum catalyst. The deprotection of sulfonate groups in the micelle corona by exposure to trimethylsilyl iodide and a treatment with aqueous HCl, followed by neutralization with aqueous NaOH, provided a polymer particle with polymer chains of sodium 4‐styrenesulfonate grafted on its surface. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1316–1323, 2007     

Unique structural characteristics of nematic ordered cellulose—Stability in water and its facile transformation

Nematic Ordered Cellulose (NOC) film that exhibits a noncrystalline yet highly ordered form was prepared by stretching a water‐swollen cellulose gel obtained in a unique manner with coagulation of cellulose molecules dissolved in the N,N‐dimethylacetamide/LiCl solvent system. In this article, structural characteristics of this unique film were investigated. Orientation of the molecular chains in the noncrystalline regions across the entire film were stable after immersing in water at room temperature, though conventional amorphous cellulose regions are in any forms believed fairly to be recrystallized under a humid atmosphere. Even 30 days after immersing in water at 50 °C, neither crystallization nor disordering of the chains occurred in the NOC film. On the contrary, the film was capable of being transformed into films composed of cellulose polymorphs domains where the molecular orientation was still maintained as the initial film under various mild conditions that both cotton and cellophane did not show any changes on their structure. These contradictory properties of the NOC film proved to be dependent on its unique supermolecular structure. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2850–2859, 2007     

Multifunctional Cyclic Carbonates Comprising Hyperbranched Polyacetals: Synthesis and Applications to Polymer Electrolytes and Networked Polymer Materials

Hyperbranched polyacetals (HBPAs) bearing cyclic carbonate (CC) terminals were synthesized from protocatechuric aldehydes bearing bifunctional trimethylolpropane (TMP) or glycerol (Gly) structures and then utilized to design polymer electrolytes and networked polymer materials. Since TMP‐based cyclic acetals (CAs) are thermodynamically more stable than Gly‐derived CSs, the copolymerization of these monomers favors to form HBPAs comprising TMP‐based acetal stems and Gly terminals. Consequently, HBPAs composed of larger amounts of TMP or Gly terminals were separately synthesized by changing monomer feed ratios. Their diol terminals react efficiently with diphenyl carbonate to give HBPAs bearing 5‐ or 6‐membered CC (5‐CC or 6‐CC) terminals. HBPAs bearing 5‐CC terminals were mixed homogeneously with lithium bis(trifluoromethanesulfonyl)imide to form uniform films showing lithium ion conductivity ranging from 8.2 × 10^?9 to 2.1 × 10^?3 S cm^?1 at 23–80 °C, whereas networked polycarbonate and polyhydroxyurethane films were successfully fabricated using HBPAs having CC terminals. These results apparently indicate that HBPAs having CC terminals are useful scaffolds to design functional polymer materials. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2295–2303     

Cationic polymerization of a novel oxetane‐bearing ionic liquid structure and properties of the obtained poly(ionic liquid)

An ionic liquid, 1‐ethyl‐3‐(3‐ethyl‐3‐oxetanylmethyl)imidazolium bis(trifluoromethanesulfonyl)imide (OXImTFSI), was synthesized, and its cationic polymerization was examined. The heating of a mixture of 1‐ethylimidazole and 3‐chloromethyl‐3‐ethyloxetane at 90 °C for 48 h yielded 1‐ethyl‐3‐(3‐ethyl‐3‐oxetanylmethyl)imidazolium chloride, which was transformed to a room‐temperature ionic liquid, OXImTFSI, by ion exchange with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). This ionic liquid was polymerized using boron trifluoride ethyl ether complex as a catalyst to give polyOXImTFSI. Five percent weight loss temperature (T_d5) of polyOXImTFSI evaluated by thermal gravimetric analysis was 409 °C, indicating the high thermal stability. Glass transition temperature (T_g) of the polymer evaluated by differential scanning calorimetry was ?19 °C, indicating the high flexibility of the material. Ionic conductivity of polyOXImTFSI was determined to be 1.86 × 10^?8 S/cm at 23 °C, which was far lower than that of the OXImTFSI monomer (5.05 × 10^?4 S/cm). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2986–2990     

Copolymerization of 2‐isothiocyanatoethyl methacrylate and 2‐hydroxyethyl methacrylate or methacrylic acid based on a nucleophile‐tolerant property of the isothiocyanato group

Radical copolymerizations of 2‐isothiocyanatoethyl methacrylate (ITEMA) and 2‐hydroxyethyl methacrylate (HEMA) or methacrylic acid (MAA) were examined, and fundamental properties of the obtained copolymers were investigated. The copolymerizations of various ITEMA/HEMA or ITEMA/MAA compositions proceeded effectively in THF or DMF by using 2,2′‐azobisbutyronitrile (AIBN) as an initiator, keeping the isothiocyanato groups and hydroxyl or carboxyl groups unchanged. Glass transition temperatures (T_g)s of poly(ITEMA‐co‐HEMA)s ranged from 68 to 100 °C, and they were thermally stable up to 200 °C. Meanwhile, T_gs of poly(ITEMA‐co‐MAA)s (ITEMA/MAA = 91/9, 76/24) were determined to be 91 and 109 °C, respectively. However, poly(ITEMA‐co‐MAA)s were thermally unstable, and significant weight loss was observed around 180 °C, which may be due to an addition of carboxyl groups to isothiocyanato groups followed by an elimination of COS to form amide structure in the copolymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5221–5229     

Water‐stable copolymers containing isocyanate moiety protected by hydrophobic styrene segment and their reaction with amines

Reactive isocyanate groups were protected and stabilized by the hydrophobic styrene segment and acquired high tolerance toward water. Copolymers containing isocyanate groups were synthesized by a radical copolymerization of 2‐propenyl isocyanate (2PI) and styrene (St). The stability of the obtained copolymers on water was examined to find that isocyanate groups were protected by the hydrophobic polystyrene segment and were stable on water and these isocyanates reacted with primary amines including amino acids to form urea selectively on water. Primary amines with a higher octanol‐water partition coefficient or smaller steric hindrance were more reactive to the isocyanate groups in the side chain of the copolymer. The protection of reactive isocyanate groups using the hydrophobic styrene segment did not give side products which are produced in the usual chemical protection/deprotection process. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1934–1940     

An accurate quantitative analysis of polymorphs based on artificial neural networks

Measurement precision based on homogeneous and accurate standard samples has been reported to result in significant improvement in the sensitivity and accuracy of the quantitative analysis of polymorphic mixtures. The purpose of this study was to further improve the accuracy of the quantitation based on data processing by artificial neural networks (ANNs), using such high quality standard samples. Homogeneous powder mixtures of - and γ-forms of indomethacin (IMC) at various ratios (0–50% -form content) were subjected to X-ray powder diffractometry. The two diffraction peaks selected as the best combination in multiple linear regression (MLR) were used in the ANN with an extended Kalman filter as a training algorithm. The results obtained by ANN had better predictive accuracy at lower contents (0–5%) compared to those of MLR. ANNs for the diffraction data based on high quality standard samples provide an extremely precise and accurate quantification for polymorphic mixtures.     

Synthesis of tetrasubstituted and functionalized enol ethers by E-selective olefination of esters with ynolates

We have developed the E-selective olefination of ester carbonyls to afford tetrasubstituted, functionalized olefins and the C-S insertion of thiol esters to give beta-keto thiol esters via ynolates.     

Detection of nanoparticles and components in smoke by time-of-flight mass spectrometry

A time-of-flight mass spectrometry (TOFMS) with a newly laboratory-made sampling cone interface fitted to an atmospheric pressure chemical ionization (APCI) positive ion source was successfully applied to easy, rapid on-line measurements of nanoparticles and components generated during combustion. The mass spectra for smoke from a mosquito coil ranged up to m/z 1202, corresponding to 1.2 nm with the carboneous material density as graphite 2.2 g cm⁻³. Typical m/z peaks were assigned to such synthetic pyrethroids, as d-allethrin and d-tetramethrin, at m/z 303 and 332, respectively. A specific pattern with a peak-to-peak interval of 74 was recognized in the higher mass range. The interval of 74 was confirmed by measuring with a standard silica solution in a positive ion mode using a conventional APCI interface under the same APCI conditions. The mass spectrum of the silica solution had a pattern with peak interval of 44 which was assigned to SiO. These results indicate that the pattern with an interval of 74 in the mass spectrum of the mosquito coil smoke is sample-derived peak. We assumed that the interval of m/z 74 is assigned to identified as triacetylene (1,3,5-hexatriyne) that is generated during the combustion.