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Keywords = N-phenylphenothiazine

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10 pages, 2163 KiB  
Article
N-Phenylphenothiazine Radical Cation with Extended π-Systems: Enhanced Heat Resistance of Triarylamine Radical Cations as Near-Infrared Absorbing Dyes
by Masafumi Yano, Minami Ueda, Tatsuo Yajima, Koichi Mitsudo and Yukiyasu Kashiwagi
Colorants 2024, 3(4), 350-359; https://doi.org/10.3390/colorants3040024 - 11 Dec 2024
Viewed by 1239
Abstract
N-Phenylphenothiazine derivatives extended with various aryl groups were designed and synthesized. These derivatives have bent conformation in crystal and exhibit high solubility. Radical cations obtained by one-electron oxidation of these derivatives gave stable radical cations in solution and showed absorption in the [...] Read more.
N-Phenylphenothiazine derivatives extended with various aryl groups were designed and synthesized. These derivatives have bent conformation in crystal and exhibit high solubility. Radical cations obtained by one-electron oxidation of these derivatives gave stable radical cations in solution and showed absorption in the near-infrared region. A radical cation was isolated as a stable salt, which exhibited heat resistance up to around 200 °C. A design strategy for radical cation-based near-infrared absorbing dyes, which are easily oxidized and stable not only as a solution but in solid form, is described. Full article
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12 pages, 2879 KiB  
Article
Photoinduced Metal-Free Surface Initiated ATRP from Hollow Spheres Surface
by Chun-Na Yan, Qian Liu, Lin Xu, Li-Ping Bai, Li-Ping Wang and Guang Li
Polymers 2019, 11(4), 599; https://doi.org/10.3390/polym11040599 - 2 Apr 2019
Cited by 17 | Viewed by 4962
Abstract
Well-defined amphiphilic diblock copolymer poly (methyl methacrylate)-b-poly (N-isopropylacrylamide) grafted hollow spheres (HS-g-PMMA-b-PNIPAM) hybrid materials were synthesized via metal-free surface-initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiators α-Bromoisobutyryl bromide (BIBB) were attached onto hollow sphere surfaces through [...] Read more.
Well-defined amphiphilic diblock copolymer poly (methyl methacrylate)-b-poly (N-isopropylacrylamide) grafted hollow spheres (HS-g-PMMA-b-PNIPAM) hybrid materials were synthesized via metal-free surface-initiated atom transfer radical polymerization (SI-ATRP). The ATRP initiators α-Bromoisobutyryl bromide (BIBB) were attached onto hollow sphere surfaces through esterification of acyl bromide groups and hydroxyl groups. The synthetic ATRP initiators (HS-Br) were further used for the metal-free SI-ATRP of methyl methacrylate (MMA) and N-isopropyl acrylamide (NIPAM) using 10-phenylphenothiazine (PTH) as the photocatalyst. The molecular weight of the polymers, structure, morphology, and thermal stability of the hybrid materials were characterized via gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), 1H-nuclear magnetic resonance spectroscopy (1H NMR), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA), respectively. The results indicated that the ATRP initiator had been immobilized onto HS surfaces successfully followed by metal-free SI-ATRP of MMA and NIPAM, the Br atom had located at the end of the main PMMA polymer chain, and the polymerization process possessed the characteristic of controlled/“living” polymerization. The thermal stability of the hybrid materials was increased significantly compared to the pure PMMA and PNIPAM. Full article
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