Synthesis and characterization of nanomagnetite thermosets based on benzoxazines

Abstract

Nanomagnetite thermosets were obtained by thermally activated ring opening copolymerization of benzoxazine groups coated on the surface of the nanomagnetite with bare benzoxazine. For this purpose, carboxylic acid containing 1,3‐benzoxazine was synthesized and covalently bonded on magnetite nanoparticles by postcoating method. The average size of benzoxazine coated nanoparticles was 40–100 nm as determined by Dynamic Light Scattering (DLS), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) measurements. The crystal structure of benzoxazine coated nanoparticles was shown to be magnetite by X‐ray diffraction (XRD) analysis. Thermally activated curing behavior of nanomagnetite‐benzoxazines has also been studied by differential scanning calorimetry (DSC). Magnetic and thermal properties of the cured samples were investigated. It was shown that the precursor nanomagnetite benzoxazine and cured samples exhibited typical ferromagnetic character with low coercivities between 1.5 and 2.5 Oe. The cured samples showed high thermal stability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6780–6788, 2008

Thiol reactive polybenzoxazine precursors: A novel route to functional polymers by thiol-oxazine chemistry

“…For example, carboxylic acid and alcohol functional benzoxazines have low curing temperatures than benzene or alkyl functional benzoxazines and curing temperatures drop down to approximately 160°C [35,36]. Hence, apart from thermally induced ring opening of 1,3-benzoxazines, alternative ring cleavage can be performed using Lewis or protic acids produced by photochemical means [37].…”

Synthesis and properties of organo-gels by thiol-benzoxazine chemistry

“…These materials offer low water absorption, high char yield and resistance against flame, high modulus, high strength, high glass transition temperatures, chemical resistance, long shelf life and dimensional stability upon curing. [1][2][3][4][5][6][7][8][9][10][11] Thus, polybenzoxazines have become one of a rare few new polymers developed and commercialized in the past 20 years. Another reason for that is benzoxazine monomers have enormous molecular design flexibility.…”

Thermal degradation of polysiloxane and polyetherester containing benzoxazine moieties in the main chain

“…Polybenzoxazines are relatively a new class of thermosetting resins that have good combination of attractive properties, such as, no release of volatiles during cure, no need for harsh catalysts, high thermal stability, good mechanical properties, excellent electrical properties, molecular design flexibility and low melt viscosity [1][2][3][4][5][6][7][8]. Polybenzoxazines are formed by thermally activated ring-opening reactions of the corresponding benzoxazines.…”