Crosslinked polyamide based on main-chain type polybenzoxazines derived from a primary amine-functionalized benzoxazine monomer (original) (raw)
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Polymer, 2006
Using difunctional phenolic and amine compounds, a new polymer with benzoxazine groups in the main chain has been synthesized through the Mannich reaction of a phenol, formaldehyde, and an amine. 1 H and 13 C nuclear magnetic resonance spectroscopies, Fourier transform infrared spectroscopy, size exclusion chromatography, and elemental analysis are used to characterize the resulting polymer. Polymer with molecular weight of approximately 10,000 Da is obtained. The resultant polymer has a moderately broad polydispersity index. The thermal properties of the polymer have also been studied by differential scanning calorimetry and thermogravimetric analysis.
Polymer, 2009
Linear polymers with benzoxazine rings in the main chain have been synthesized applying click chemistry approach. These polymers possess molecular weights significantly higher than the benzoxazine polymers which have been chain extended via Mannich reaction. The number average molecular weight is estimated from size exclusion chromatography (SEC) to be between 20,000 and 40,000 Da. The structure of the polymers is confirmed by 1 H and 13 C nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry (DSC) is used to study crosslinking behavior of the polymers. The nature of the low temperature exotherm DSC peak observed in this work and the previous work of other authors is studied by model reactions. It is due to thermal coupling of the residual propargyl and azide end groups in the absence of active catalyst. In addition, a novel diazide-functional benzoxazine monomer has been prepared, showing a tremendous flexibility for applying click reaction to obtain various polymer architectures. Three types of polymers have been prepared from dipropargyl-and diazide-functional benzoxazine monomers. These polymers have been characterized by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA).
Various Approaches for Main-Chain Type Benzoxazine Polymers
Handbook of Benzoxazine Resins, 2011
s0010 1. INTRODUCTION p0110 Polybenzoxazines are a class of thermosetting resins that compare favorably with traditional thermosets, such as phenolic, epoxy, bismaleimides, and cyanate ester resins, and cross-linkable polyimides with additional unusual properties. The unique properties of benzoxazines make them ideal for various applications where these traditional monomers have failed. Among these properties are low water absorption, extremely rich molecular design flexibility, fast property development at low conversion, and near-zero shrinkage upon polymerization [1,2]. The early research on the chemistry of polybenzoxazines focused on the monomeric type, where a monofunctional amine, phenol, and formaldehyde react in a Mannich condensation reaction to release water and afford a classical benzoxazine monomer, as shown in Scheme 1. Upon heating to 160-220 C, benzoxazine undergoes ring-opening polymerization, and cross-linked polybenzoxazine is produced. Schemes 2 and 3 show two main classes of difunctional benzoxazine monomers: the combination of bisphenol and monoamine,
Design and synthesis of thermally curable polymers with benzoxazine functionalities
Macromolecular Symposia, 2006
In this paper, synthetic strategies for the preparation of structurally different polymers, namely polystyrene (PSt), poly(ε-caprolactone) (PCL), poly(propyleneoxide) (PPO), poly(methyl methacrylate) (PMMA), and poly(styrene-alt- maleimide) (PSt-alt-MI) with thermally curable benzoxazine groups have been outlined. Specifically, these groups were incorporated into PSt and PCL by using two controlled polymerization methods, namely Atom Transfer Radical Polymerization (ATRP) and Ring Opening Polymerization (ROP), respectively. Modification of linear and branched poly(propylene amine)s via Mannich reaction yields the corresponding benzoxazine functional PPOs. The photoinitiated polymerization of olefinic monomers such as methyl methacrylate by using benzoxazines as hydrogen donor in conjunction with aromatic carbonyl compounds is another suitable method for the desired functionalization. Moreover, benzoxazine substituted maleimide was copolymerized with styrene to yield perfectly alternating benzoxazine functional copolymers (PSt-alt-MI).
Macromolecular Chemistry and Physics, 2013
Isocyanate functional benzoxazine (NCO-4HBA-a) is used for coupling with hydroxyl-groupcontaining molecules. Glycerol is used in a model reaction to study the urethane bonds formed between the NCO-4HBA-a and the glycerol's hydroxyl groups. The model supports a reaction between NCO-4HBA-a and poly(vinyl alcohol) (PVA), which leads to an improved char yield, determined by thermogravimetric analysis. Glycerol-based benzoxazine is also an attractive benzoxazine synthesized from the products of biofuel production. Upon functionalization with benzoxazine and subsequent thermal treatment, the hydroxyl-containing polymer gains thermal stability shown by improved char yield of polybenzoxazine cross-linked PVA.
Synthesis and properties of new polybenzoxazines containing (substituted) cyclohexyl moieties
Polymers for Advanced Technologies, 2009
A series of new polybenzoxazines were synthesized based on diphenols containing (substituted) cyclohexyl moiety and were characterized by FT-IR, 1 H-NMR, and 13 C-NMR spectroscopy. These new benzoxazine monomers exhibited better processability with lower peak cure temperature and a wide cure controllable window (CCW) as manifested in differential scanning calorimetric analysis. The cure analysis was performed by FT-IR spectroscopy. Glass transition temperature of new polybenzoxazines varied from 170 to 205-C. The cyclohexyl bridge groups facilitated ring opening, resulting in polymer with improved thermal stability in comparison to bisphenol A-based benzoxazine as assessed by the various thermal analyses. The water contact angles of polybenzoxazines containing (substituted) cyclohexyl moieties were higher than that of bisphenol A-based polybenzoxazine, implying their higher hydrophobicity.
Synthetic Strategies to Combine High Performance Benzoxazine Thermosets with Polymers
Macromolecular Symposia, 2010
Polybenzoxazines are newly developed thermosetting polymers exhibiting versatility in a wide range of applications including electronics and aerospace industries. They exhibit highly competitive combination of properties compare to the conventional thermosets. In this paper we present synthetic strategies to incorporate thermally curable benzoxazine functions into polymers as main and side chain groups in order to further improve various properties. The strategies successfully employed include monomer synthesis, macromonomer method, polycondensation, oxidative polymerization, photo-polymerization, click chemistry and hydrosilylation processes. In the case of macromononomer method functional initiators were used in various controlled/living polymerizations to give polymers with benzoxazine end groups. The thermal curing behaviors of the obtained polymers were also demonstrated.
NActivated 1,3-Benzoxazine Monomer as a Key Agent in Polybenzoxazine Synthesis
A novel and successful application of ring-closing reactions of aminophenols has been proposed for the formation of a new type of 1,3-benzoxazine ionic derivatives. The optimization of the reaction and detailed computational studies have been reported for the estimation of heterocyclic ring stability and its further transformation, which is crucial in the polymerization process. The molecular structure of the obtained compounds has been fully characterized by applying X-ray analysis and spectroscopic methods. The novel benzoxazines undergo an intriguing thermal reaction leading to classical benzoxazines and chloroalkanes, which is the first step of transformation before polymerization. To gain more insights into the transformation behavior of ionic benzoxazine derivatives, the Fourier transform infrared (FT-IR) spectra of gaseous products were recorded in experiments with near simultaneous FT-IR/TGA measurements. The combination of thermogravimetry with FT-IR spectroscopy enables the quantitative and qualitative characterization of thermal transformation products and clarification of the reaction mechanism. The experimental data have been verified by applying DFT(B3LYP) and DFT(M062x) theoretical studies.
Reactive and Functional Polymers, 2014
The thermally activated ring-opening polymerization behavior of benzoxazine based on 4,4 0 -diaminodiphenyl ether was investigated by Fourier transform infrared and differential scanning calorimetry, and the thermal properties of the corresponding polybenzoxazine were studied by dynamic mechanical analysis, thermogravimetry-mass spectrometry, and differential thermal analysis. In the ring-opening polymerization reaction, the C-O-C absorption peak of the oxazine ring at 1,054 cm -1 disappeared first, and the C-N-C absorption intensity of the oxazine ring decreased gradually with time rising. The activation energies of the non-isothermal polymerization are 83.4 and 87.4 kJ mol -1 evaluated with Kissinger and Flynn-Wall-Ozawa methods, respectively. Dynamic mechanical analysis shows the glass transition temperature of the resultant polybenzoxazine is 188°C. In the thermal degradation, the 10 % mass loss temperature of the polybenzoxazine is 353°C and the char yield is about 48 % at 800°C in nitrogen, while 415°C and close to 0 % at 650°C in air.