Benzoxazine Polymers

Liu et al. [8] reported improved processability of main-chain benzoxazine polymers by synthesizing novel benzoxazine main-chain oligomers which are low in viscosity. Bisphenol-F based benzoxazine monomers were obtained from the reaction of bisphenol-F isomers, para-formaldehyde and aniline in toluene. Main chain benzoxazine oligomers were obtained by the reaction involving 

Choi et al. [9] also reported the synthesis of functional benzoxazine monomers and polymers containing phenylphosphine oxide. Phosphorus-containing group was introduced into polybenzoxazine via monomer modification. Three phosphorus-containing bisphenol compounds, bis(4-hydroxyphenyl)phenylphosphine oxide (BHPPO), bis(4-hydroxyphenoxyphenyl) phenylphosphine 

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Keywords Polyfether amide) and polyfether amide-imide), polyfarylene ether), benzoxazine polymers, polyfether ether ketone) (PEEK), polytriazole, hyperbranched conjugated polymers, alternating copolymers... 

Poly(phenylquinoxaline—arnide—imides) are thermally stable up to 430°C and are soluble in polar organic solvents (17). Transparent films of these materials exhibit electrical insulating properties. Quinoxaline—imide copolymer films prepared by polycondensation of 6,6 -meth5lene bis(2-methyl-3,l-benzoxazine-4-one) and 3,3, 4,4 -benzophenone tetracarboxyUc dianhydride and 4,4 -oxydianiline exhibit good chemical etching properties (18). The polymers are soluble, but stable only up to 200—300°C. 

Nonsegmented, monophase polymers, 221 Novolac-epoxy networks, 414 Novolac-HMTA cures, hydroxyben-zylamine and benzoxazine decompositions in, 392-398 Novolac networks... 

With the increasing demand for chiral nonracemic compounds, stereoselective methods for the synthesis of 1,3-oxazine derivatives and applications of enantiopure 1,3-oxazines in asymmetric transformations have gained in importance in the past decade, as reflected by the increasing trend in the number of publications on this topic, and accordingly by the share of this topic in the present compilation. The limited size of this survey and the scope of this chapter do not allow a discussion here of the applications of 1,3-oxazines in polymer chemistry and the synthesis and properties of 1,3-benzoxazine-containing hetero-calixarenes. 

The reactivity of the maleimide monomer was dependent on the substitution pattern of the phenyl ring, with the substituents in the ortho position tending to lower the molecular weight of the polymer formed. The THP substituent is readily removed either chemically or thermally to yield poly(iV-(hydroxyphenyl)maleimides). All polymers exhibited excellent thermal stability and showed no evidence of degradation below 360 °C. Reaction occurs between the phenolic ring of the polyimide and HMTA, to form benzoxazine-type derivatives. These reactions have been studied comprehensively using the monomeric model systems, Ai-(hydroxyphenyl)succinimides (Figure 8) . 

Photoinitiated Cationic Polymerization of Unusual Monomers Recently, novel monomers and macromonomers (Chart 11.12), namely, benzoxazines, monothiocarbonates, thiophene, and epoxy and vinyl ether functional polymers were reported to undergo photoinitiated cationic polymerization [2,118], Among them, benzoxazine monomers deserves a special attention as they yield thermosets with several excellent characteristics including heat resistance good flame retardance stable dielectric constants low water absorption and perfect dimensional stability. This type of thermosets is also obtained by thermally activated ring-opening polymerization at elevated temperatures without catalysts [19]. 

Other thermosetting polymers are cyanate esters (CEs), benzoxazines, PU acrylates, bismaleimides (BMIs), dicy-clopentadienes (DCPDs), diallyl phthalates (DAPs), etc. Formulations based on these polymers are used for specific applications where their particular properties are required. For example, DAP has long been the material of choice for electrical components where long-term reliability is required. 

Figure 15.8 Principle of synthesis and polymerization of difunctional benzoxazines, using the example of B-a and the resulting crosslinked polymer PB-a.

A number of classes of additives specifically for use as UV absorbers in polymer formulations are available including, among the better known ones, aromatic salicylates [11], o-hydroxybenzophenones [12], 2-hydroxyphenylbenzotriazoles [12,13], derivatives of cinnamic acid and related materials [14,15], aromatic oxanilides [16], cyclic imino ester derivatives known varionsly as benzoxazines or benzoxazones [17, 18] and hydroxyphenyltriazines [19]. 

Coordination polymers containing rotaxane linkers 12CSR5896. Design and synthesis of cross-Hnked poly(benzoxazine)- and polybenzimidazole-based copolymer membranes and their application to an electrolyte membrane for a high-temperature PEM fuel cell 13P77. 

Schreiber, for the preparation of phenolic resins with improved thermal, mechanical, and dielectric characteristics. However, no systematic study was reported in Schreiber s patents. Thus, it was of interest to examine in more detail several points such as 1) the synthesis of an homologeous series of benzoxazines, 2) their reaction with phenols, which may be considered as the initiation step of the polymerization by a ring opening mechanism, 3) the pol3nnerization kinetics of benzoxazines, initiated either thermally or with phenols, and 4) the application possibilities of these monomers and polymers. 

It was noted that the reaction rate for benzoxazine Jx is distinctly lower than that observed for benzoxazine lb. The average molecular weights of the polymer formed at 140°C are summarized in Table 8. 

Calo E, Maffezzoli A, Mele G, Martina F, Mazzetto S E, Tarzia A and Stifani C (2007), Synthesis of a novel cardanol-based benzoxazine monomer and environmentally sustainable production of polymers and bio-composites . Green Chem, 9, 754-759. 

Grishchuk S, Mbhele Z, Schmitt S and Karger-Kocsis J (2011), Structure, thermal and fracture mechanical properties of benzoxazine-modified amine-cured DGEiBA epoxy resins . Express Polym Lett, 5, 213—2W., and references therein. 

Rao B S and Palanisamy A (2011), Monofunctional benzoxazine from cardanol for biocomposite applications . React Fund Polym, 71, 148-154, and references therein. 

Yang P and Gu Y (2012), Synthesis of a novel benzoxazine-containing benzoxazole structure and its high performance thermoset , J Appl Polym Sci, 124, 2415-2422. Yoonessi M, Toghiani H, Wheeler R, Porcar L, Kline S and Pittman Jr C U (2008), Neutron scattering, electron microscopy and dynamic mechanical studies of carbon nanofiber/phenolic resin composites . Carbon, 46, 577-588, and references therein. Yosomiya R (1990), Adhesion and Bonding in Composites, New York, Marcel Dekker, l-A. 

SCHEME 13.1 Preparation of cross-linked polybenzoxazine resin through possible reactions of the retro-DA reaction, the benzoxazine ring-opening reaction, and the maleimide addition reaction. (Adapted from Chou Chou L, and Liu Ying-Ling. J. Polym. Sci. Part A. 46 no. 19 (2008) 6509-6517.)... 

Examples of additives are the following EA = iodonium salt, e.g. diphenyliodonium hexafluorophosphate (more rarely, a sulfonium salt) and related derivatives [113], alkyl halide, e.g. phenacyl bromide [1.14] and triazine, e.g. 2,4,6-tris(trichloromethyl)-l,3,5-triazine ED = borate disulfide, group IVb dimetal [1.15] HD = alcohol, THE, thiol, benzoxazine, aldehyde, acetal, silane (e.g. tris(trime1hylsilyl)silane = (TMS)3Si-H) [1.16]), germane, borane, stannane, alkoxyamine, silyloxyamine, polymer substrate, etc. EPD = amine [1.17], thiol, etc. The generated radicals (e.g. Ph, R, RsSi, RR C R R in [1.13]-[1.17] ) are the initiating species. Efficient novel or newly modified dye structures in the Dye/amine, Dye/iodonium salt or Dye/silane two-component PISs have been proposed within the last 4 years (see section 1.3.5). 

KAS 03b] Kasapoglu F., Cianga 1., Yagci Y. et al, Photoinitiated cationic polymerization of monofunctional benzoxazine . Journal of Polymer Science Part A Polymer Chemistry, vol. 41, pp. 3320-3328,2003. 

More recently, the same photodimerization was exploited by Yagci et al, who functionalized linear or three-armed star-shaped poly(propylene oxide)s with two or three terminal benzoxazine coumarin functions, respectively [KIS 14], These products were used as multifunctional macromolecular precursors for the preparation of self-healing pol5mier films. Under irradiation at wavelengths over 300 nm, the formation of cyclobutane junctions from the chain-end chromophores of the macromonomers resulted in cross-linking. Regarding the recovery of mechanical properties, a healing efficiency up to 44% was obtained in the case of a cracked polymer sample studied in this work. 

Some examples of miscibility can be highlighted. For example, thermosetting polymer blends composed of bisphenol A-based benzoxazine (BA-a) and cyanate... 

Recently, Schmidt et al. reported the novel microporous polymer network 70, which was prepared via oxidative coupling of 3,3 -dithienyl BINOL derived phosphoric acid (Scheme 32.17). This interesting chiral polymer shows good activity for the asymmetric hydrogenation of benzoxazine 41, even after reuse four times (ee 47%-56%) [39]. 

Figure 9.1 Examples of carbocyclic and heterocyclic repeating units used to build the macromolecular backbone of heat-resistant polymers I poly (1,4-phenylene) or poly(para-phenylene), II benzimidazole, III benzoxazole, IV benzothiazole, V isoindoledione (imide), VI pyrroledione or maleimide, VII bicycloheptylpyrroledione or nadimide, VIII quinoline, IX benzoxazine, X quinazoline, and XI quinoxaline.

Inata H and Matsumura S (1987) Chain extenders for polyesters. V. Reactivities of hydroxyl-addition-type chain extender 2,2 -bis(4H-3,l-benzoxazin-4-one), J Appl Polym Sci 34 2609-2617. 

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