Synthesis and properties of a novel highly thermal stable N-propargyl monomer containing benzoxazole ring

A novel highly thermal stable propargyl functional compound containing benzoxazole ring, N, N, N′, N′-tetra propargyl-5-amino-2-(p-aminophenyl) benzoxazole (TPAPB), was proposed and synthesized using a phase-transfer catalytic method. The cure behavior of TPAPB was investigated by non-isothermal differential scanning calorimetry analysis. The solubility and rheological properties of TPAPB, as well as its broad temperature window from 130°C to 200°C with low viscosity, offered excellent processability for TPAPB to be used as a potential monomer of thermosetting polymer resin. It was found that the glass transition temperature of cured TPAPB was 359°C, and the temperature of 5% weight loss was 418°C in argon with the char residue up to 70% at 700°C. The polymerized resin exhibited high heat resistance and thermal stability, together with its processability, making it good candidate as highly heat-resistant polymer matrix for advanced composite applications.

Preparation and characterization of novel polybenzoxazine hybrid materials

The novel polybenzoxazine hybrid materials were prepared using 6,6′-(9H-fluorene-9,9-diyl)bis(3-allyl-3,4-dihydro-2H-benzo-1,3-oxazine) (VF9Bp), 4,4′-bisphenol silane as raw materials. The chemical structure of the raw materials was confirmed by proton, carbon, and silicon nuclear magnetic resonance and Fourier transform infrared (FTIR) spectroscopies. The structural changes from benzoxazines to their corresponding polybenzoxazines were studied by FTIR. Thermal characterization indicated that the glass transition temperature, thermal stability, and dimensional stability of the novel polybenzoxazine hybrid materials were all superior to those of conventional polybenzoxazine.

High Performance Polybenzoxazines as Novel Thermosets

Polybenzoxazine as a novel phenolic type thermoset has been developed to overcome the shortcomings associated with the use of the traditional phenolics. It can be prepared from cyclic benzoxazines via thermally induced ring-opening polymerization. Various benzoxazine monomers can be synthesized from mono-or diamines and mono-or bisphenols with formaldehyde. Polybenzoxazines have not only the advantageous properties of conventional phenolic resins such as high thermal properties, but also other interesting advantages that are not found in the traditional phenolic resins such as excellent dimensional stability. The disadvantages of the typical polybenzoxazines are the high temperature needed for complete cure and the brittleness of the cured materials. Further improvement of thermal properties is also expected for application in harsh conditions. Herein we report on various approaches for performance improvement of polybenzoxazine. These approaches include alloying with other high performance polymers, hybridization with inorganics, and designing of novel monomers as well as high molecular weight polymeric precursors. By these approaches, lowering of the cure temperature, improvement of toughness, and enhancement of thermal and mechanical properties were achieved.

Thermal, mechanical and antibacterial properties of cyclophosphazene incorporated benzoxazine blended bismaleimide composites

Cyclophosphazene is incorporated in to Bz–Bmi composites in order to improve the thermal, mechanical, electrical resistance and antibacterial properties of CP–Bz–Bmi composite.

Effect of iron acetylacetonate on the crosslink structure, thermal and flammability properties of novel aromatic diamine-based benzoxazines containing cyano group

Fe(AcAc)₃ speeds up the curing reaction of BAPBACP monomer and improves the thermal and flammability properties of the cured resin.

Design of hydrophobic polydimethylsiloxane and polybenzoxazine hybrids for interlayer low k dielectrics

Graphical representation of layer-by-layer arrangement of polydimethylsiloxane based polybenzoxazine hybrids.

Polymer alloys of high-molecular-weight benzoxazine and epoxy resin

Novel polymer alloys were prepared by curing the mixture of a high-molecular-weight benzoxazine (B-oda) that was synthesized from 4,4′-oxydianiline (oda), bisphenol-A, and formaldehyde and a typical epoxy resin prepolymer, epoxy-terminated copolymer of bisphenol-A and epichlorohydrin, up to 240°C. It was confirmed by differential scanning calorimetric and infrared (IR) investigations that the novel alloys had ether linkages that was formed by the reaction between the phenolic hydroxyl groups formed from the thermal ring-opening polymerization of B-oda and the epoxy groups of the epoxy resin. The properties of the alloy films were compared with polybenzoxazine (PB-oda), the pristine polybenzoxazine obtained by curing B-oda without the epoxy resin. The alloy films were more flexible and were found to have higher glass transition temperatures ( Tgs) from the dynamic mechanical analyses. From the IR analyses of the films, the polymer alloys were found to have higher amount of intermolecular hydrogen bonding compared with the pristine PB-oda. It was suggested that this increase of the hydrogen bonding was the cause of the higher Tgs of the polymer alloys.

Preparation and properties of polymer alloys consisting of high-molecular-weight benzoxazine and bismaleimide

Novel polymer alloys were prepared by blending a high-molecular-weight benzoxazine (HMWB) and a typical bismaleimide (4,4′-bismaleimidodiphenyl methane (BMI)) followed by thermal treatment up to 240°C. It was confirmed by the infrared and differential scanning calorimetric analyses that the phenolic hydroxyl group formed by the ring-opening polymerization of HMWB reacted with the double bond of BMI, in addition to the chain polymerization of the double bond of BMI and the ring-opening polymerization of HMWB. This further cross-linking through the formation of ether linkage made the polymer alloy films much more tough and flexible than each homopolymer film. Moreover, viscoelastic analyses and thermogravimetric analyses of the polymer alloy films showed that glass transition temperature and thermal stability also increased by alloying.

Highly cross-linked thermosetting benzocyclobutene-modified bis-benzoxazine resins from 4-hydroxybenzocyclobutene

In the present study, benzocyclobutene (BCB) was incorporated into the benzoxazine (BOZ) monomers. BCB-functionalized BOZ monomers were synthesized by the reaction of 4-hydroxybenzocyclobutene, aromatic diamine, and paraformaldehyde in dioxane under reflux. The structure of the monomers was characterized by Fourier transform infrared spectroscopy (FTIR) and proton and carbon nuclear magnetic resonance spectroscopies. The monomers possess two kinds of ring-opening polymerizable functional groups, BCB and BOZ. Differential scanning calorimetry and FTIR were used to study the polymerization behavior of the monomers. Dynamic mechanical analysis demonstrates that the related polymers show high storage moduli maintained in a wide range of temperature up to 300°C and high glass transition temperature at about 330°C. The incorporation of BCB improved the thermal stability and mechanical property of the monomer.

Preparation and properties of silicon-containing arylacetylene resin/benzoxazines blends

A series of aniline-based bifunctional benzoxazines (BZs) were synthesized using solventless or solvent method via the Mannich condensation reactions. The chemical structures of these BZs were confirmed using Fourier-transform infrared and proton-nuclear magnetic resonance spectroscopies. The polymer blends were prepared by mixing silicon-containing arylacetylene (poly(dimethylsilyleneethynylenephenyleneethynylene) (PSA)) resin with BZ in weight ratios at 110°C until a homogeneous viscosity liquid was obtained. The resultant blends were characterized by solubility tests, rheological analyses, differential scanning calorimetry, dynamic mechanical analyses and thermogravimetric analyses. The good solubility and low melt viscosity of the blends indicated excellent processability. The curing reactions resulted in the formation of interpenetrating polymer networks. The cured blends exhibited high glass transition temperatures (T gs) and thermal stabilities. The compressive strength and flexural strength of the blend casts improved when compared with pristine PSA.