Study of the Effects of Intramolecular and Intermolecular Hydrogen‐Bonding Systems on the Polymerization of Amide‐Containing Benzoxazines

A phenol/aniline type monofunctional benzoxazine monomer, PH‐a, is synthesized and highly purified to study the intrinsic thermal ring‐opening polymerization of benzoxazines without the influence of any impurity. The successful synthesis of the monomer and its corresponding chemical structure are confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. Purity of the compound is evaluated through differential scanning calorimetry (DSC) as well as elemental analysis (EA). Moreover, the thermal behavior of benzoxazine monomer toward polymerization is also studied by DSC, indicating that the highly purified benzoxazine monomer actually polymerize upon heating. The results present evidence of an intrinsic tendency for 1,3‐benzoxazines to undergo thermally induced ring‐opening polymerization upon heating only without any impurity participating during the reaction. This reveals that polybenzoxazines can be obtained by both the traditional thermally accelerated (or activated) polymerization, where impurities or purposefully added initiators are involved in the reaction; or, by the classic thermal polymerization, where only heat is enough to initiate the reaction. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3434–3445

show abstract

“…Synthesis of PH‐a was carried out in a solvent‐less method following a modified reported procedure, as shown in Scheme .…”

Section: Resultsmentioning

confidence: 99%

Intrinsic self‐initiating thermal ring‐opening polymerization of 1,3‐benzoxazines without the influence of impurities using very high purity crystals

Han¹,

Salum

Zhang

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Among these monomers, o HTI-a was the only one that has a crystal-to-crystal phase-transition [27,32]; hence, the unexpected low melting temperature of o HTI-a can be attributed to the formation of less stable crystalline structures. Besides, the thermograms showed that the maxima of the ring-opening polymerization for o MHI-a, o HHI-a, o HTI-a, and o PP-a centers at 258, 254, 252, and 234 °C, respectively, which were all lower than that of PH-a (a phenol- and aniline-based benzoxazine monomer) [33]. This suggests that the incorporation of the imide group into benzoxazine reduces the ring-opening polymerization temperature of the oxazine ring, e.g., through electro-withdrawal at the ortho -position of the oxazine ring.…”

Section: Resultsmentioning

confidence: 99%

Effects of End-Caps on the Atropisomerization, Polymerization, and the Thermal Properties of ortho-Imide Functional Benzoxazines

et al. 2019

Self Cite

View full text Add to dashboard Cite

A new type of atropisomerism has recently been discovered in 1,3-benzoxazines, where the intramolecular repulsion between negatively charged oxygen atoms on the imide and the oxazine ring hinders the rotation about the C–N bond. The imide group offers a high degree of flexibility for functionalization, allowing a variety of functional groups to be attached, and producing different types of end-caps. In this work, the effects of end-caps on the atropisomerism, thermally activated polymerization of ortho-imide functional benzoxazines, and the associated properties of polybenzoxazines have been systematically investigated. Several end-caps, with different electronic characteristics and rigidities, were designed. 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations were employed to obtain structural information, and differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy were also performed to study the thermally activated polymerization process of benzoxazine monomers. We demonstrated that the atropisomerization can be switched on/off by the manipulation of the steric structure of the end-caps, and polymerization behaviors can be well-controlled by the electronic properties of the end-caps. Moreover, a trade-off effect were found between the thermal properties and the rigidity of the end-caps in polybenzoxazines.

show abstract

“…During this curing process, the biophenol-based benzoxazine undergoes ring-opening polymerization followed by the formation of intermolecular hydrogen bonding of H–O…H and O–H…N molecules, as shown in Figure 3, which is a good agreement with the previous reports. 26 –29…”

Section: Methodsmentioning

confidence: 99%

Advanced development of dairy farm waste-based biocarbon-reinforced unsymmetrical structured bio-phenolic polybenzoxazine composites

Selvaraj

Raghavarshini

Alagar

2020

High Performance Polymers

View full text Add to dashboard Cite

In the present work, an attempt has been made to develop cow manure carbon-reinforced hybrid biophenol-based benzoxazine composites for antifouling coating applications. Bio-based benzoxazine with unsymmetrical molecular structure was synthesized using the mixture of a combination of cardanol and eugenol with diaminodiphenyl methane and paraformaldehyde, and the hybrid-benzoxazine obtained was characterized using different analytical techniques, viz., Fourier transform infrared, nuclear magnetic resonance and MALDI mass. Bio-based benzoxazine was further reinforced with varying weight percentages (1, 3 and 5 wt%) of biocarbon derived from cow manure to obtain hybrid composite coatings. The hybrid benzoxazine matrix and composites were studied for their thermal behaviour, contact angle (CA), morphology, corrosion-resistant behaviour and antifouling character to utilize them as coatings materials for different industrial applications. Results obtained from different studies inferred that the biocarbon-reinforced composites possess an enhanced value of glass transition temperature (249°C), high char yield (38.4%), improved CA (105.6°), higher efficiency of corrosion protection against mild steel surface (98%) and improved antimicrobial activity.

show abstract

Study of the Effects of Intramolecular and Intermolecular Hydrogen‐Bonding Systems on the Polymerization of Amide‐Containing Benzoxazines

Cited by 57 publications

References 42 publications

Intrinsic self‐initiating thermal ring‐opening polymerization of 1,3‐benzoxazines without the influence of impurities using very high purity crystals

Intrinsic self‐initiating thermal ring‐opening polymerization of 1,3‐benzoxazines without the influence of impurities using very high purity crystals

Effects of End-Caps on the Atropisomerization, Polymerization, and the Thermal Properties of ortho-Imide Functional Benzoxazines

Advanced development of dairy farm waste-based biocarbon-reinforced unsymmetrical structured bio-phenolic polybenzoxazine composites

Contact Info

Product

Resources

About