Developing Further Versatility in Benzoxazine Synthesis via Hydrolytic Ring-Opening

In this study, 2-(aminomethyl)phenol and its derivatives, the reactants for 2-substituted 1,3-benzoxazines, are synthesized by HCl hydrolysis from the typical benzoxazines. The phenol/ aniline-based mono-oxazine benzoxazine, PH-a, and the bisphenol A/aniline-based bis-oxazine benzoxazine, BA-a, are used as examples to demonstrate the feasibility of this new approach. Their chemical structures are characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and Raman spectroscopies, and are further verified by elementary analysis. Their thermal properties are studied by differential scanning calorimetry (DSC). These two 2-(aminomethyl) phenolic derivatives are reacted with paraformaldehyde to close the oxazine rings. A benzoxazine with a phenyl substituent at the 2-position of the oxazine ring is obtained from the 2-(phenylamino)methyl)phenol (hPH-a) and benzaldehyde. All these results highlight the success of the HCl hydrolysis and the formation of stable intermediates, namely 2-(aminomethyl) phenolic derivatives, from readily available benzoxazine monomers. This further demonstrates the feasibility of using these intermediates as reactants for a novel benzoxazine synthesis.Fil: Cui, Shaoying. Sichuan University; ChinaFil: Arza, Carlos R.. Case Western Reserve University; Estados UnidosFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina. Case Western Reserve University; Estados UnidosFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido

Synthesis, Thermal Properties, and Rheological Characteristics of Indole-Based Aromatic Polyesters

Currently, there is an intensive development of bio-based aromatic building blocks to replace fossil-based terephthalates used for poly(ethylene terephthalate) production. Indole is a ubiquitous aromatic unit in nature, which has great potential as a bio-based feedstock for polymers or plastics. In this study, we describe the synthesis and characterization of new indole-based dicarboxylate monomers with only aromatic ester bonds, which can improve the thermal stability and glass-transition temperature (Tg) of the resulting polyesters. The new dicarboxylate monomers were polymerized with five aliphatic diols to yield 10 new polyesters with tunable chemical structures and physical properties. Particularly, the Tg values of the obtained polyesters can be as high as 113 °C, as indicated by differential scanning calorimetry and dynamic mechanical analysis. The polyesters showed decent thermal stability and distinct flow transitions as revealed by thermogravimetric analysis and rheology measurements

Indole as a new sustainable aromatic unit for high quality biopolyesters

The aim of this research was to use indole as a new sustainable aromatic unit for polyesters. A series of new polyesters were synthesised by the polycondensation of an indole-based dicarboxylate and five potentially bio-based diols. The new polyesters are amorphous, have superior thermal quality, and can form clear transparent films

Biocompatible non-leachable antimicrobial polymers with a nonionic hyperbranched backbone and phenolic terminal units

This work aimed to develop biocompatible non-leachable antimicrobial polymers without ionic structures. A series of nonionic hyperbranched polymers (HBPs) with an isatin-based backbone and phenolic terminal units were synthesized and characterized. The molecular structures and thermal properties of the obtained HBPs were characterized by SEC, NMR, FTIR, TGA and DSC analyses. Disk diffusion assay revealed significant antibacterial activity of the obtained phenolic HBPs against nine different pathogenic bacteria. The presence of a methoxy or long alkyl group close to the phenolic unit enhanced the antibacterial effect against certain Gram positive and negative bacteria. The obtained nonionic HBPs were blended in polyester poly(hexamethylene terephthalate) films, which showed no noticeable leakage after being immersed in water for 5 days. Finally, these HBPs showed no cytotoxicity effect to MG-63 osteoblast-like human cells according to MTT analysis, and negligible hemolytic effect

Design, Synthesis, Characterization, and Polymerization of Fused-Ring Naphthoxazine Resins

Fused-ring naphthoxazine monomers are synthesized from 1-naphthols and cycloimines derived from piperidine and pyrrolidine. Their polymerization has been confirmed by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR) as well as by solution and solid-state 1H and 13C nuclear magnetic resonance spectroscopy (NMR). A polymerization reaction similar to the traditional benzoxazine monomers is found with oxazine ring disappearing and hydroxyl group forming by the nonisothermal FT-IR experiment. Fused-ring monomers, studied in this work, polymerize at significantly lower temperatures compared to the ordinary benzoxazine resins.Fil: Arza, Carlos R.. Case Western Reserve University; Estados UnidosFil: Froimowicz, Pablo. Case Western Reserve University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Han, Lu. Case Western Reserve University; Estados UnidosFil: Graf, Robert. Max Planck Institute For Polymer Research; AlemaniaFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido

Efficient up-conversion in Yb:Er:NaT(XO4)2 thermal nanoprobes. Imaging of their distribution in a perfused mouse

Yb and Er codoped NaT(XO) (T = Y, La, Gd, Lu and X = Mo, W) disordered oxides show a green (Er3+ related) up-conversion (UC) efficiency comparable to that of Yb:Er:β-NaYF4 compound and unless 3 times larger UC ratiometric thermal sensitivity. The similar UC efficiency of Yb:Er doped NaT(XO) and β-NaYF4 compounds allowed testing equal subcutaneous depths of ex-vivo chicken tissue in both cases. This extraordinary behavior for NaT (XO) oxides with large cutoff phonon energy (h 920 cm-1) is ascribed to 4F9/2 electron population recycling to higher energy 4G11/2 level by a phonon assisted transition. Crystalline nanoparticles of Yb:Er:NaLu(MoO) have been synthesized by sol-gel with sizes most commonly in the 50-80 nm range, showing a relatively small reduction of the UC efficiency with regards to bulk materials. Fluorescence lifetime and multiphoton imaging microscopies show that these nanoparticles can be efficiently distributed to all body organs of a perfused mouse.This work has been supported by the Ministry of Economy and Competitiveness (MINECO) and by the European Regional Development Fund through MAT2014-56607-R project. The CNIC is supported by the Ministry of Economy, Industry and Competitiveness (MEIC) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (SEV-2015-0505)

Oxazine Ring-Related Vibrational Modes of Benzoxazine Monomers Using Fully Aromatically Substituted, Deuterated, 15N Isotope Exchanged, and Oxazine-Ring-Substituted Compounds and Theoretical Calculations

Polymerization of benzoxazine resins is indicated by the disappearance of a 960-900 cm-1 band in infrared spectroscopy (IR). Historically, this band was assigned to the C-H out-of-plane bending of the benzene to which the oxazine ring is attached. This study shows that this band is a mixture of the O-C2 stretching of the oxazine ring and the phenolic ring vibrational modes. Vibrational frequencies of 3-phenyl-3,4-dihydro-2H-benzo[e][1,3]oxazine (PH-a) and 3-(tert-butyl)-3,4-dihydro-2H-benzo[e][1,3]oxazine (PH-t) are compared with isotope-exchanged and all-substituted compounds. Deuterated benzoxazine monomers, 15N-isotope exchanged benzoxazine monomers, and all-substituted benzoxazine monomers without aromatic C-H groups are synthesized and studied meticulously. The various isotopic-exchanges involved deuteration around the benzene ring of phenol, selective deuteration of each CH2 in the O-CH2-N (2) and N-CH2-Ar (4) positions on the oxazine ring, or simultaneous deuteration of both positions. The chemical structures were confirmed by 1H nuclear magnetic resonance spectroscopy (1H NMR). The IR and Raman spectra of each compound are compared. Further analysis of 15N isotope-exchanged PH-a indicates the influence of the nitrogen isotope on the band position, both experimentally and theoretically. This finding is important for polymerization studies of benzoxazines that utilize vibrational spectroscopy.Fil: Han, Lu. Case Western Reserve University; Estados UnidosFil: Iguchi, Daniela. Case Western Reserve University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gil, Phwey. Case Western Reserve University; Estados UnidosFil: Heyl, Tyler R.. Case Western Reserve University; Estados UnidosFil: Sedwick, Victoria M.. Case Western Reserve University; Estados UnidosFil: Rodriguez Arza, Carlos. Case Western Reserve University; Estados UnidosFil: Ohashi, Seishi. Case Western Reserve University; Estados UnidosFil: Lacks, Daniel J.. Case Western Reserve University; Estados UnidosFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido

Efficient up-conversion in Yb:Er:NaT(XO₄)₂ thermal nanoprobes. Imaging of their distribution in a perfused mouse

<div><p>Yb and Er codoped NaT(XO₄)₂ (T = Y, La, Gd, Lu and X = Mo, W) disordered oxides show a green (Er³⁺ related) up-conversion (UC) efficiency comparable to that of Yb:Er:β-NaYF₄ compound and unless 3 times larger UC ratiometric thermal sensitivity. The similar UC efficiency of Yb:Er doped NaT(XO₄)₂ and β-NaYF₄ compounds allowed testing equal subcutaneous depths of <i>ex-vivo</i> chicken tissue in both cases. This extraordinary behavior for NaT(XO₄)₂ oxides with large cutoff phonon energy (ħω≈ 920 cm^-1) is ascribed to ⁴F_9/2 electron population recycling to higher energy ⁴G_11/2 level by a phonon assisted transition. Crystalline nanoparticles of Yb:Er:NaLu(MoO₄)₂ have been synthesized by sol-gel with sizes most commonly in the 50–80 nm range, showing a relatively small reduction of the UC efficiency with regards to bulk materials. Fluorescence lifetime and multiphoton imaging microscopies show that these nanoparticles can be efficiently distributed to all body organs of a perfused mouse.</p></div

Comparison of up-conversion properties of DMo/DW and β-NaYF₄.

<p>RT UC characteristics of Yb:Er:DMo/DW in comparison to Yb:Er:β-NaYF₄ upon cw DL excitation with 4 W/cm² of light density. a) UC spectral distribution of 25at%Yb:5at%Er:NaLu(MoO₄)₂ synthesized by solid state reaction. (b) UC spectral distribution of HT 10at%Yb:1at%Er:β-NaYF₄. Indicated multiplets are those emitting to the ground ⁴I_15/2 one. Note that for a given material the intensity of blue, green and red UC, although arbitrary, is in the same scale. (c) Evolution of the green UC efficiency of Yb:Er:NaY(WO₄)₂ as a function of Yb and Er concentrations. (d) Evolution of the green UC efficiency of HT Yb:Er:β-NaYF₄ as a function of Yb and Er concentrations. (e) Maximum green UC efficiencies achieved for 15at%Yb:1at%Er:NaT(XO₄)₂ (shorten as NaTX) synthesized by solid state reaction (●) or HT (▲) methods, relative to HT 7.5at%Yb:0.5at%Er:β-NaYF₄ (line). (f) Comparison of NaY(WO₄)₂ and β-NaYF₄ thermometric properties.</p