Synthesis of a Novel Phosphorus- and Nitrogen-Containing Acrylate and Its Performance as an Intumescent Flame Retardant for Epoxy Acrylate

A New Phosphorous/Nitrogen-Containing Flame-Retardant Film with High Adhesion for Jute Fiber Composites

In this work, a novel P/N flame-retardant monomer (PDHAA) was synthesized through reacting phenyl dichlorophosphate (PDCP) with N-hydroxyethyl acrylamide (HEAA). The structure of PDHAA was confirmed using Fourier transform infrared (FTIR) spectroscopy and proton nuclear magnetic resonance (NMR) spectroscopy. PDHAA monomer and 2-hydroxyethyl methacrylate phosphate (PM-2) monomer were mixed at different mass ratios, to prepare UV-curable coatings, and then applied to the surface of fiber needled felts (FNFs), to improve their flame retardancy. PM-2 was introduced to reduce the curing time of the flame-retardant coatings and improve the adhesion between the coating and the fiber needled felts (FNFs). The research results indicated that the surface flame-retardant FNFs had a high limiting oxygen index (LOI) and rapidly self-extinguished in a horizontal combustion test and passed a UL-94 V-0 test. At the same time, the CO and CO₂ emissions were greatly reduced, and the carbon residue rate was increased. In addition, the introduction of the coating improved the mechanical properties of the FNFs. Therefore, this simple and efficient UV-curable surface flame-retardant strategy has broad application prospects in the field of fire protection.

Stimuli-Responsive Multifunctional Phenylboronic Acid Polymers Via Multicomponent Reactions: From Synthesis to Application

Stimuli-responsive polymers undergo changes under different environmental conditions. Among them, phenylboronic acid (PBA) containing polymers (PBA-polymers) are unique, because they can selectively react with diols to generate borates that are sensitive to pH, sugars, and H₂ O₂ , and can be effectively used to synthesize smart drug carriers and self-healing hydrogels. Recently, multifunctional PBA-polymers (MF-PBA-polymers) have been developed using multicomponent reactions (MCRs) to introduce PBA groups into polymer structures. These MF-PBA-polymers have features similar to those of traditional PBA-polymers; moreover, they exhibit additional properties, such as fluorescence, antimicrobial activity, and antioxidant capability, when different MCRs are used. In this mini review, the preparation of these MF-PBA-polymers are summarized and the new properties/functions that have been introduced into these polymers using different MCRs are discussed. The uses of these MF-PBA-polymers as fluorescent cell anticoagulants, drug carriers, and gelators of functional self-healing hydrogels have been discussed. Additionally, the challenges encountered during their preparation are discussed and also the future developments in this field are touched upon.

Antioxidant Polymers via the Kabachnik-Fields Reaction to Control Cellular Oxidative Stress

Small molecular antioxidants are almost ineffective in regulating harmful oxidative stress in vivo because of their poor bioavailability. Polymer antioxidants are a promising alternative to address this issue, but their laborious synthetic routes limit their development. In this study, aliphatic and aromatic aldehydes are used to synthesize a family of polymers containing different α-aminophosphonate pendant groups via a facile one-pot method that combines the Kabachnik-Fields (KF) reaction and free radical polymerization. The structure-property relationship study of these polymers reveals the KF moieties in polymer structures confer radical scavenging ability on polymers. The radical scavenging ability and cytotoxicity of these polymers are evaluated in a stepwise manner to identify a biocompatible polymer antioxidant that can effectively protect the cells from H₂ O₂ -induced oxidative damage. This is the first attempt to develop antioxidative polymers by the KF reaction. It highlights the feasibility of synthesizing new functional polymers using multicomponent reactions, which has important implications for organic and polymer chemistry.

Synthesis of a novel modified chitosan as an intumescent flame retardant for epoxy resin

According to the concept of fire life cycle assessment (LCA), a new type of intumescent flame retardant was designed and synthesized by chemically bonding chitosan, phosphorus pentoxide and melamine. The resultant compound, chitosan ethoxyl melamine phosphate (CEMP), was characterized by FTIR, 1H NMR, 31P NMR, XRD and SEM. The performance of CEMP and organic montmorillonite (OMMT) was evaluated in the substrate of epoxy resin (EP) with limited oxygen index (LOI), UL-94, cone calorimetric test (CCT), TGA and TG-IR. As a result, intumescent flame retardant EP (EP3) containing 30.6% LOI and V-0 rating was prepared by adding 3 wt% OMMT and 15 wt% CEMP. The CCT results indicated that CEMP and OMMT reduced the peak of heat release rate (PHRR) to about one fourth that of pure EP and total heat release (THR), 1/2. Decomposition of EP and EP3 was traced from 100 to 600°C by TG-IR.

Flame Retardant Epoxy Composites on the Road of Innovation: An Analysis with Flame Retardancy Index for Future Development

Nowadays, epoxy composites are elements of engineering materials and systems. Although they are known as versatile materials, epoxy resins suffer from high flammability. In this sense, flame retardancy analysis has been recognized as an undeniable requirement for developing future generations of epoxy-based systems. A considerable proportion of the literature on epoxy composites has been devoted to the use of phosphorus-based additives. Nevertheless, innovative flame retardants have coincidentally been under investigation to meet market requirements. This review paper attempts to give an overview of the research on flame retardant epoxy composites by classification of literature in terms of phosphorus (P), non-phosphorus (NP), and combinations of P/NP additives. A comprehensive set of data on cone calorimetry measurements applied on P-, NP-, and P/NP-incorporated epoxy systems was collected and treated. The performance of epoxy composites was qualitatively discussed as Poor, Good, and Excellent cases identified and distinguished by the use of the universal Flame Retardancy Index (FRI). Moreover, evaluations were rechecked by considering the UL-94 test data in four groups as V0, V1, V2, and nonrated (NR). The dimensionless FRI allowed for comparison between flame retardancy performances of epoxy composites. The results of this survey can pave the way for future innovations in developing flame-retardant additives for epoxy.

Grafting heteroelement-rich groups on graphene oxide: Tuning polarity and molecular interaction with bio-ionic liquid for enhanced lubrication

Two different heteroelement-rich molecules have been successfully grafted on graphene oxide (GO) sheets which were then used as lubricant additives in bio-ionic liquid. The grafting was processed with reactions between GO sheets and synthesized heteroelement-rich molecules (Imidazol-1-yl phosphonic dichloride and 1H-1,2,4-triazol-1-yl phosphonic dichloride, respectively). The modified GO (m-GO) was added into [Choline][Proline] ([CH][P]) bio-ionic liquid, and has been demonstrated effective additive in promoting lubrication. Different characterization techniques have been utilized to study the reaction between GO and the two modifiers. The effect of molecular structure of the modifiers on the rheological and tribological properties of m-GO/[CH][P] lubricants was systematically investigated. Both theoretical calculation and experimental results demonstrated that the introduced heteroelement-rich groups are beneficial to increase the robustness of lubrication film by intensified hydrogen bonding and enhance the lubricant/friction surface adhesion by increased polarity of the m-GO. As a result, the interfacial lubrication could be significantly improved by these newly developed m-GO/[CH][P] lubricants.

Study of the thermal stability and flame retardant properties of graphene oxide-decorated zirconium organophosphate based on polypropylene nanocomposites

Preparation routes of polypropylene/Zr(AE)₃P, polypropylene/GO-Zr(AE)₃P nanocomposites.