scholarly journals Synthesis of Pluri-Functional Amine Hardeners from Bio-Based Aromatic Aldehydes for Epoxy Amine Thermosets

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3285
Author(s):  
Mora ◽  
Tayouo ◽  
Boutevin ◽  
David ◽  
Caillol
Keyword(s):  
Mechanical Properties ◽  
Aromatic Aldehydes ◽  
Diglycidyl Ether ◽  
Reaction Conditions ◽  
High Mechanical Strength ◽  
Alkyl Chains ◽  
Low Viscosity ◽  
Epoxy Amine ◽  
Molecular Length ◽  
Step Growth

Most of the current amine hardeners are petro-sourced and only a few studies have focused on the research of bio-based substitutes. Hence, in an eco-friendly context, our team proposed the design of bio-based amine monomers with aromatic structures. This work described the use of the reductive amination with imine intermediate in order to obtain bio-based pluri-functional amines exhibiting low viscosity. The effect of the nature of initial aldehyde reactant on the hardener properties was studied, as well as the reaction conditions. Then, these pluri-functional amines were added to petro-sourced (diglycidyl ether of bisphenol A, DGEBA) or bio-based (diglycidyl ether of vanillin alcohol, DGEVA) epoxy monomers to form thermosets by step growth polymerization. Due to their low viscosity, the epoxy-amine mixtures were easily homogenized and cured more rapidly compared to the use of more viscous hardeners (<0.6 Pa s at 22 °C). After curing, the thermo-mechanical properties of the epoxy thermosets were determined and compared. The isophthalatetetramine (IPTA) hardener, with a higher number of amine active H, led to thermosets with higher thermo-mechanical properties (glass transition temperatures (Tg and Tα) were around 95 °C for DGEBA-based thermosets against 60 °C for DGEVA-based thermosets) than materials from benzylamine (BDA) or furfurylamine (FDA) that contained less active hydrogens (Tg and Tα around 77 °C for DGEBA-based thermosets and Tg and Tα around 45 °C for DGEVA-based thermosets). By comparing to industrial hardener references, IPTA possesses six active hydrogens which obtain high cross-linked systems, similar to industrial references, and longer molecular length due to the presence of two alkyl chains, leading respectively to high mechanical strength with lower Tg.

scholarly journals Build-To-Specification Vanillin and Phloroglucinol Derived Biobased Epoxy-Amine Vitrimers

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2645
Author(s):  
Aratz Genua ◽  
Sarah Montes ◽  
Itxaso Azcune ◽  
Alaitz Rekondo ◽  
Samuel Malburet ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Renewable Resources ◽  
Diglycidyl Ether ◽  
Vanillyl Alcohol ◽  
Molecular Architecture ◽  
Covalent Bonds ◽  
Thermoset Resins ◽  
Epoxy Amine ◽  
Reversible Covalent ◽  
Epoxy Matrices

Epoxy resins are widely used in the composite industry due to their dimensional stability, chemical resistance, and thermo-mechanical properties. However, these thermoset resins have important drawbacks. (i) The vast majority of epoxy matrices are based on non-renewable fossil-derived materials, and (ii) the highly cross-linked molecular architecture hinders their reprocessing, repairing, and recycling. In this paper, those two aspects are addressed by combining novel biobased epoxy monomers derived from renewable resources and dynamic crosslinks. Vanillin (lignin) and phloroglucinol (sugar bioconversion) precursors have been used to develop bi- and tri-functional epoxy monomers, diglycidyl ether of vanillyl alcohol (DGEVA) and phloroglucinol triepoxy (PHTE) respectively. Additionally, reversible covalent bonds have been incorporated in the network by using an aromatic disulfide-based diamine hardener. Four epoxy matrices with different ratios of epoxy monomers (DGEVA/PHTE wt%: 100/0, 60/40, 40/60, and 0/100) were developed and fully characterized in terms of thermal and mechanical properties. We demonstrate that their performances are comparable to those of commonly used fossil fuel-based epoxy thermosets with additional advanced reprocessing functionalities.

DFT Study and Synthesis of Novel Bioactive Bispyrazole Using Mg/AlLDH as a Solid Base Catalyst

2020 ◽  
Vol 14 ◽  
Author(s):  
Soufiane Akhramez ◽  
Youness Achour ◽  
Mustapha Diba ◽  
Lahoucine Bahsis ◽  
Hajiba Ouchetto ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Experimental Finding ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Aromatic Aldehydes ◽  
Mechanistic Study ◽  
Knoevenagel Reaction ◽  
Solid Base ◽  
Reaction Conditions ◽  
Aryl Aldehyde

Background: In this study, an efficient synthesis of novel bispyrazole heterocyclic molecules by condensation of substituted aromatic aldehydes with 1,3-diketo-N-phenylpyrazole by using Mg/Al-LDH as heterogeneous catalyst is reported. The attractive features of this protocol are as follows: mild reaction conditions, good yields and easiness of the catalyst separation from the reaction mixture. Further, a mechanistic study has been performed by using DFT calculations to explain the observed selectivity of the condensation reaction between aryl aldehyde and 1,3-diketo-N-phenylpyrazole via Knoevenagel reaction. The local electrophilicity/ nucleophilicity that allows explaining correctly the experimental finding. Methods: The bispyrazole derivatives 3a-m were prepared by condensation reaction of substituted aromatic aldehydes with 1,3-diketo-Nphenylpyrazole by using Mg/Al-LDH as heterogeneous catalyst under THF solvent at the refluxing temperature. Objective: To synthesize a novel bispyrazole heterocyclic molecule may be have important biological activities and thus can be good candidates for pharmaceutical applications. Results: This protocol describes the Synthesis of Bioactive Compounds under mild reaction conditions, good yields and easiness of the catalyst separation from the reaction mixture. Further, a mechanistic study has been performed by using DFT calculations to explain the observed selectivity of the condensation reaction between aryl aldehyde and 1,3-diketo-N-phenylpyrazole via Knoevenagel reaction. The local electrophilicity/ nucleophilicity that allows explaining correctly the experimental finding. Conclusion: In summary, the pharmacologically interesting bis-pyrazole derivatives have been synthesized through Mg/Al-LDH as a solid base catalyst, in THF as solvent. Thus, the synthesized bioactive compounds containing the pyrazole ring may be have important biological activities and thus can be good candidates for pharmaceutical applications. Therefore, the catalyst Mg/Al-LDH showed high catalytic activity. Besides, a series of bispyrazole molecules were synthesized with a good yield and easy separation of the catalyst by simple filtration. Moreover, DFT calculations and reactivity indexes are used to explain the selectivity of the condensation reaction between aryl benzaldehyde and 1,3-diketo-Nphenylpyrazole via Knoevenagel reaction, and the results are in good agreement with the experimental finding.

scholarly journals High-strength and fibrous capsule–resistant zwitterionic elastomers

2021 ◽  
Vol 7 (1) ◽  
pp. eabc5442
Author(s):  
Dianyu Dong ◽  
Caroline Tsao ◽  
Hsiang-Chieh Hung ◽  
Fanglian Yao ◽  
Chenjue Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
High Strength ◽  
Design Principles ◽  
Fibrous Capsule ◽  
High Mechanical Strength ◽  
Capsule Formation ◽  
Locking Mechanism ◽  
Fibrous Capsule Formation

The high mechanical strength and long-term resistance to the fibrous capsule formation are two major challenges for implantable materials. Unfortunately, these two distinct properties do not come together and instead compromise each other. Here, we report a unique class of materials by integrating two weak zwitterionic hydrogels into an elastomer-like high-strength pure zwitterionic hydrogel via a “swelling” and “locking” mechanism. These zwitterionic-elastomeric-networked (ZEN) hydrogels are further shown to efficaciously resist the fibrous capsule formation upon implantation in mice for up to 1 year. Such materials with both high mechanical properties and long-term fibrous capsule resistance have never been achieved before. This work not only demonstrates a class of durable and fibrous capsule–resistant materials but also provides design principles for zwitterionic elastomeric hydrogels.

scholarly journals Bisphenol-Free Epoxy Resins Derived from Natural Resources Exhibiting High Thermal Conductivity

Proceedings ◽  
2020 ◽  
Vol 69 (1) ◽  
pp. 18
Author(s):  
Matthias Sebastian Windberger ◽  
Evgenia Dimitriou ◽  
Frank Wiesbrock
Keyword(s):  
Thermal Conductivity ◽  
Natural Resources ◽  
Polymer Networks ◽  
Sio2 Nanoparticles ◽  
Diglycidyl Ether ◽  
Epoxy Compound ◽  
Inorganic Materials ◽  
Limiting Factor ◽  
Epoxy Amine ◽  
Π Stacking

Polymers commonly have low thermal conductivity in the range of 0.1–0.2 W·m−1·K−1, which is a limiting factor for their usage in the course of continuously increasing miniaturization and heat generation in electronic applications. Two strategies can be applied to increase the transport of phonons in polymers: (i) the embedment of thermally conductive inorganic materials and (ii) the involvement of aromatic units enabling anisotropy by π–π stacking. In this study, the thermal conductivity of resins based on bisphenol A diglycidyl ether BADGE and 1,2,7,8-diepoxyoctane DEO was compared. DEO can be derived from pseudo-pelletierine, which is contained in the bark of the pomegranate tree. The epoxy compounds were cured with isophorone diamine IPDA, o-dianisidine DAN, or mixtures of the both diamines. Notably, isophorone diamine is derived from isophorone of which the latter naturally occurs in cranberries. The formulations were produced without filler or with 5 wt.-% of SiO2 nanoparticles. Significantly enhanced thermal conductivity in the range of 0.4 W·m−1·K−1 occurs only in DEO-based polymer networks that were cured with DAN (and do not contain SiO2 fillers). This observation is argued to originate from π–π stacking of the aromatic units of DAN enabled by the higher flexibility of the aliphatic carbon chain of DEO compared to that of BADGE. This assumption is further supported by the facts that significantly improved thermal conductivity occurs only above the glass-transition temperature and that nanoparticles appear to disrupt the π–π stacking of the aromatic groups. In summary, it can be argued that the bisphenol-free epoxy/amine resin with an epoxy compound derivable from natural resources shows favorably higher thermal conductivity in comparison to the petrol-based epoxy/amine resins.

A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ajinkya More ◽  
Thomas Elder ◽  
Zhihua Jiang
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidative Degradation ◽  
Reaction Medium ◽  
Dicarboxylic Acids ◽  
Aromatic Aldehydes ◽  
Product Distribution ◽  
Reaction Conditions ◽  
Alkaline Conditions ◽  
The Stability ◽  
Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

Mechanichal Properties of DGEBA/TEPA Modified Epoxy Resin

2014 ◽  
Vol 775-776 ◽  
pp. 588-592
Author(s):  
Camila Rodrigues Amaral ◽  
Ruben Jesus Sanchez Rodriguez ◽  
Magno Luiz Tavares Bessa ◽  
Verônica Scarpini Cândido ◽  
Sergio Neves Monteiro
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Epoxy Resin ◽  
Yield Stress ◽  
Diglycidyl Ether ◽  
Notch Toughness ◽  
Epoxy Network ◽  
Structural Network ◽  
Flexural Tests ◽  
Modified Epoxy

The correlation between the structural network of a diglycidyl ether of the bisphenol-A (DGEBA) epoxy resin, modified by two distinct aliphatic amines (tetraethylenepentamine TEPA and jeffamine D230), and its mechanical properties, was investigated as possible matrix for abrasive composites applications. Both flexural tests, to determine the yield stress and the elastic modulus, as well as impact tests to determine the notch toughness, were performed. The DGEBA/D230 presented the highest stiffness and toughness but lowest yield stress. This epoxy network also displayed a greater plastic deformation during fracture.

scholarly journals Effect of Tartaric Acid on the Printable, Rheological and Mechanical Properties of 3D Printing Sulphoaluminate Cement Paste

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2417 ◽  
Author(s):  
Mingxu Chen ◽  
Xiangyang Guo ◽  
Yan Zheng ◽  
Laibo Li ◽  
Zhen Yan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
3D Printing ◽  
Tartaric Acid ◽  
Apparent Viscosity ◽  
Setting Time ◽  
Sulphoaluminate Cement ◽  
Low Viscosity ◽  
Ultimate Deformation ◽  
Rapid Setting

Rapid setting and low viscosity of sulphoaluminate cement (SAC) make it difficult to be extruded by 3D printing (3DP) technique. In this study, the effect of tartaric acid (TA) on printability, rheology and mechanical property of 3DP SAC paste is investigated. The experimental results indicate that the setting time, hydration evolution and apparent viscosity of SAC paste can be well controlled by adding a proper amount of TA to satisfy the requirements of 3DP. An excellent structure of SAC paste with the ultimate deformation rate less than 10% can be printed without compromising mechanical strength.

scholarly journals Synthesis of new Cα-tetrasubstituted α-amino acids

2009 ◽  
Vol 5 ◽  
Author(s):  
Andreas A Grauer ◽  
Burkhard König
Keyword(s):  
Amino Acids ◽  
Secondary Structure ◽  
Aromatic Aldehydes ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Peptide Backbone ◽  
Aliphatic Aldehydes ◽  
New Class ◽  
Cyclic Amino Acids

Cα-Tetrasubstituted α-amino acids are important building blocks for the synthesis of peptidemimetics with stabilized secondary structure, because of their ability to rigidify the peptide backbone. Recently our group reported a new class of cyclic Cα-tetrasubstituted tetrahydrofuran α-amino acids prepared from methionine and aromatic aldehydes. We now report the extension of this methodology to aliphatic aldehydes. Although such aldehydes are prone to give aldol products under the reaction conditions used, we were able to obtain the target cyclic amino acids in low to moderate yields and in some cases with good diastereoselectivity.

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