Recyclable and Fluorescent Epoxy Polymer Networks from Cardanol Via Solvent-Free Epoxy-Thiol Chemistry

Abstract

The development of multifunctional polymeric materials from renewable resources is of foremost significance from a sustainable development perspective. In this work, a biobased epoxy monomer (EHCPP) with hard core structures and multi-arms was prepared from cardanol with hexachlorocyclotriphosphazene, followed by epoxidation with m-chloroperoxybenzoic acid (m-CPBA). Then, the epoxy polymer networks were prepared via the curing process of EHCPP with four thiol monomers of different thiol groups. The mechanical and thermomechanical properties, thermal stability, solvent resistance, recyclability characteristics, and optical behavior of the cardanol-based epoxy resins were systematically investigated. The results showed that four epoxy resins (EHCPP-2SH, EHCPP-3SH, EHCPP-4SH, and EHCPP-BDB) not only exhibited excellent solvent resistance in 10 wt % aqueous solutions of NaOH, HCl, and NaCl but also showed intrinsic fluorescence, while only the EHCPP-BDB epoxy resin showed phosphorescence behavior. Recyclability was observed in the EHCPP-BDB polymer network due to the presence of dynamic reversible boron ester bonds. These cardanol-based epoxy-thiol polymer networks open a pathway to explore potential biomass resources for high-performance multifunctional materials as a replacement for petroleum-based thermosets in various industrial applications.

Detailed Thermal, Fire, and Mechanical Study of Silicon-Modified Epoxy Resin Containing Humic Acid and Other Additives

“…Further, extensive use of bio-based compounds can destroy the earth’s regenerative capacity, giving rise to further environmental issues. Thus, in the context of sustainable development, the reuse of biowaste materials as functional flame retardant additives for polymer-based systems may represent one of the most promising approaches for moving toward a circular economy concept. , Among biowastes, humic acids (HAs) are the alkali-soluble fraction of natural organic matter obtained by the biological and chemical degradation of both vegetable and animal biomasses . HAs consist of a skeleton of aliphatic or aromatic units, with a marked amphiphilic behavior.…”

“…5,10 Among biowastes, humic acids (HAs) are the alkali-soluble fraction of natural organic matter obtained by the biological and chemical degradation of both vegetable and animal biomasses. 11 HAs consist of a skeleton of aliphatic or aromatic units, with a marked amphiphilic behavior. These moieties are stabilized by weak hydrophobic, hydrogen, and metal-bridged electrostatic bonds in supramolecular architectures that can change their functionalities depending on the chemical environment.…”

Biobased covalent adaptable networks: towards better sustainability of thermosets

“…18). 190 A biobased epoxy monomer with stiff core structures and soft multiarms was synthesized in two steps. In detail, the cardanol was first reacted with hexachlorocyclotriphosphazene and then epoxidized using m -chloroperoxybenzoic acid to obtain a biobased epoxy monomer.…”

Thermally Stable, Solvent Resistant, and Multifunctional Thermosetting Polymer Networks with High Mechanical Properties Prepared from Renewable Plant Phenols via Thiol–Ene Photo Click Chemistry

“…Zhang et al developed an epoxy monomer with hard core structures and multiarms by substitution reaction between cardanol and hexachlorocyclotriphosphazene followed by epoxidation with m -chloroperoxybenzoic acid. After curing with four thiol monomers, the resulting polymer networks exhibited excellent thermal stability and solvent resistance . Gu et al prepared trifunctional allyl monomers through a substitution reaction between eugenol and POCl 3 in an aqueous system.…”

“…After curing with four thiol monomers, the resulting polymer networks exhibited excellent thermal stability and solvent resistance. 14 Gu et al prepared trifunctional allyl monomers through a substitution reaction between eugenol and POCl 3 in an aqueous system. After curing with various thiols by solvent-free photo polymerization process, the resulting polymer networks exhibited excellent high tensile strength up to 19.8 MPa and modulus up to 601.6 MPa.…”