Synthesis and Cross-Linking of a Benzoxazine-Containing Anthracene Moiety: Thermally Stable Photoluminescent Benzoxazine Resin

Abstract

A novel benzoxazine derivative, 9,10-bis­(6-ethynyl-3-phenyl-3,4-dihydro-1,3-benzoxazine)­anthracene (1a), was synthesized by the Sonogashira–Hagihara coupling reaction of 9,10-dibromoanthracene and 6-ethynyl-3-phenyl-3,4-dihydro-1,3-benzoxazine. A CH2Cl2 solution of 1a luminesced with a high quantum yield (Φ = 81%). Compound 1a afforded solvent-insoluble cross-linked polybenzoxazine 1b by the bulk polymerization at 250 °C. Solution polymerization of a dilute solution of 1a at 200 °C afforded solvent-soluble samples, accompanied by a decrease of photoluminescence intensity. The weight loss values of 1a and 1b were 81 and 87%, respectively, under nitrogen at 500 °C. We believe that the present study will lead to thermally stable curing resins whose degree of curing can be estimated with the naked eye by observing the decrease of photoluminescence.

Polycyclic Aromatic Hydrocarbons Bearing Polyethynyl Bridges: Synthesis, Photophysical Properties, and their Applications

“…Very recently, Sanda and co‐workers described the photoluminescence properties of anthracene core benzoxacine molecules ( 20 a and 20 e ) (Figure 2). [89] Owing to the presence of π‐conjugation between lone pair electrons of oxygen atom and anthracene moiety in 20 e , it exhibited λ onset and λ max that are longer than the corresponding absorptions in 20 a by 30 nm and 12 nm respectively. Both 20 a and 20 e displayed absorption spectra with similar splitting patterns in the range 440–480 nm with 20 e exhibiting two distinct peaks at 494 and 524 nm in emission spectra.…”

“…While 20 e and 20 a gave a quantum yield of 80% in DCM, the corresponding values were 65% and 93% for 20 e and 20 a respectively in sulfolane. The relatively lower quantum yield of 20 e in polar solvents such as sulfolane is attributed to aggregation because of the synergistic effect involving the interaction between anthracene‐ethynyl units and terminal phenyl groups much like that present in the solid‐state [89] . On lowering the temperature from 25 °C to 0 °C, the quantum yield of 20 e increased from 80% to 86% in DCM and 65% to 72% in sulfolane medium.…”

Synthesis of a triptycene-containing dioxazine benzoxazine monomer and a main-chain triptycene-polydimethysiloxane-benzoxazine copolymer with excellent comprehensive properties

“…Benzoxazines are a class of six-membered heterocyclic compounds that can be readily synthesized via Mannich condensation reacting phenolic compounds, primary amines, and formaldehyde. 1,2 Their derived polymers, namely polybenzoxazines, [3][4][5] are a new series of high-performance thermosets that have been regarded as an efficient alternative to commercialized epoxies, bismaleimides, and phenolic resins due to their combined properties and advantages, such as very low shrinkage and lack of byproduct release during the curing process, 6 high char yield, [5][6][7][8][9][10][11][12][13][14][15][16][17][18] low dielectric constant, [19][20][21] low flammability, [22][23][24] low moisture absorption, 25 low surface free energy, 26,27 and excellent gas capture capability. [28][29][30] These attractive characteristics make polybenzoxazines suitable for many advanced applications, including electronics, adhesives, coatings, and fiber-reinforced composites.…”

“…Over recent decades, intensive efforts have been devoted to elaborating new benzoxazine resins because of the rich molecular design flexibility offered by 1,3-benzoxazine compounds toward polymerization. 2,4 Many chemical functionalities, such as spiro skeletons, 31 octafluorocyclopentene, 20 maleimide, 15,32 amide, 33 anthracene, 12 and thioamide, 34 have been incorporated as constitutive moieties of benzoxazine monomers to further enhance the important properties of their polymers, such as thermal, mechanical, and electric properties. In addition to the synthesis of 1,3-benzoxazine monomers, the synthesis of oligomers and polymers possessing benzoxazines in their main chain has also attracted great attention from both academic and industrial researchers.…”

Ethynylene-linked multifunctional benzoxazines: the effect of the ethynylene group and packing on thermal behavior

“…We have reported the synthesis and curing behavior of various ethynylene-linked benzoxazines, including anthracenylethynylene 23 and phenyleneethynylene, 24 and also polyacetylenes bearing benzoxazine moieties. 25 We have determined that incorporation of ethynylene and π-conjugated moieties can enhance the thermal stability of benzoxazines by formation of network structures during the ring-opening polymerization of benzoxazine moieties or by incorporation of ethynylene moieties.…”