Synthesis, characterization, and thermal properties of phosphorus-containing, wholly aromatic thermotropic copolyesters

Advanced Flame-Retardant Methods for Polymeric Materials

Most organic polymeric materials have high flammability, for which the large amounts of smoke, toxic gases, heat, and melt drips produced during their burning cause immeasurable damages to human life and property every year. Despite some desirable results having been achieved by conventional flame-retardant methods, their application is encountering more and more difficulties with the ever-increasing high flame-retardant requirements such as high flame-retardant efficiency, great persistence, low release of heat, smoke, and toxic gases, and more importantly not deteriorating or even enhancing the overall properties of polymers. Under such condition, some advanced flame-retardant methods have been developed in the past years based on "all-in-one" intumescence, nanotechnology, in situ reinforcement, intrinsic char formation, plasma treatment, biomimetic coatings, etc., which have provided potential solutions to the dilemma of conventional flame-retardant methods. This review briefly outlines the development, application, and problems of conventional flame-retardant methods, including bulk-additive, bulk-copolymerization, and surface treatment, and focuses on the raise, development, and potential application of advanced flame-retardant methods. The future development of flame-retardant methods is further discussed.

High fire-safety phosphorus-containing polyethylene terephthalate with well-balanced comprehensive performances by reactive blending with liquid crystalline copolyester

With increased public awareness of fire-safety, flame retardant materials have been widely used and developed. Among them, a polyester called CPET, synthesized by the copolymerization of polyethylene terephthalate and 2-carboxyethyl (phenyl) phosphinic acid, has a good fire-safety and has been employed in the manufacture of synthetic fibers. However, the fabricated fiber made of CPET simultaneously possessing good flame retardancy and mechanical properties is a dilemma. Herein, we resolve this problem through the reactive blending of CPET with a type of thermotropic liquid crystal copolyester (PPDT) and subsequently solid-state polymerization (SSP). Thus, the fire-safety of the CPET/PPDTSSP blend improves greatly. The peak heat release rate, total heat release, and total smoke release decrease by 31.2%, 16.3%, and 11.0%, respectively, compared with those of CPET. Meanwhile, the CPET/PPDTSSP shows better crystallization and mechanical properties than CPET. The strength at yield and Young’s modulus of CPET/PPDTSSP increase by 20.0% and 15.8%, respectively. This blend shows great potential in the fabrication of fire-safety fibers with high strength.

Towards Sustainable High-Performance Thermoplastics: Synthesis, Characterization, and Enzymatic Hydrolysis of Bisguaiacol-Based Polyesters

The utilization of wood-derived building blocks (xylochemicals) to replace fossil-based precursors is an attractive research subject of modern polymer science. Here, we demonstrate that bisguaiacol (BG), a lignin-derived bisphenol analogue, can be used to prepare biobased polyesters with remarkable thermal properties. BG was treated with different activated diacids to investigate the effect of co-monomer structures on the physical properties of the products. Namely, derivatives of adipic acid, succinic acid, and 2,5-furandicarboxylic acid were used. Moreover, a terephthalic acid derivative was used for comparison purposes. The products were characterized by ¹ H NMR spectroscopy, attenuated total reflectance FTIR spectroscopy, gel-permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry to assess their structural and thermal properties in detail. The polymers showed glass-transition temperatures ranging up to 160 °C and thermal stabilities in excess of 300 °C. Furthermore, the susceptibility of the polyester to enzymatic hydrolysis was investigated to assess the potential for further surface functionalization and/or recycling and biodegradation. Indeed, hydrolysis with two different enzymes from the bacteria Thermobifida cellulosilytica led to the release of monomers, as quantified by HPLC. The results of this study indicate that our new polyesters represent promising renewable and biodegradable alternatives to petroleum-based polyesters currently employed in the plastics industry, specifically for applications in which high-temperature stability is essential to ensure overall system integrity.

Design and Synthesis of PET-Based Copolyesters with Flame-Retardant and Antidripping Performance

Poly(ethylene terephthalate) (PET) is a fiber-forming polymer with the largest output and widest usage. Its flame retardation is well-achieved via a mechanism of promoting the melt dripping while ignited. However, the melt dripping leads to secondary damage and an immediate empyrosis during fire. How to address the contradiction between the flame retardation and the melt-dripping behavior of PET via an inherent flame-retardant approach becomes a real challenge. This feature article highlights the design and synthesis of novel PET-based copolyesters with flame-retardant and antidripping performance. Three approaches are used to design these copolyesters: "ionic aggregation," "smart self-cross-linking," and "rearrangement at high temperatures." Some new conceptions are proposed accordingly. The synthesis, structure characterization, and properties of those copolyesters are discussed together with the ongoing challenges and limitations at this frontier.

Synthesis and Properties of some Phosphorus-containing Polyesters

Phosphorus-containing polyesters were prepared by polycondensation of 2-(6-oxido-6H-dibenz >c,e< >1,2< oxaphosphorin-6-yl)-1,4-benzenediol with different aromatic dicarboxylic acids using a SOCl2/pyridine condensing agent. The polymers were soluble in polar organic solvents such as N-methylpyrrolidone, N, N-dimethylformamide, tetrahydrofuran and chloroform. They showed high thermal stability having a decomposition temperature above 360°C and char yield at 700°C in the range of 19-32%. The glass transition temperature was in the range of 180-194°C. Solutions of the polymers in N, N-dimethylformamide showed fluorescence having maximum emission wavelength around 362 nm. One of the polymers exhibited thermotropic liquid crystalline behavior

Synthetic investigation of glycine catalyzed triarylimidazole based organophosphorous heterocyclic functionalized vinyl polymer - A green approach

In the present investigation, an efficient and environmentally adopted synthesis of triaryl substituted imidazole in one-pot was reported. The multicomponent reaction between various aldehydes, benzil, benzoin, ammonium acetate and glycine under solvent free condition has been explained. Instead of using toxic reagents for the synthesis of heterocyclic compounds, Glycine has been selected as a green catalyst due to simple work-up procedure, shorter reaction time and high yield. The synthesized imidazole derivatives on further treatment with phosphorous oxychloride resulted in an organophosphorous containing N-heterocyclic compound (N-P) thus by altering acidic hydrogen of imidazole. Further, N-P was reacted with polyvinyl alcohol resulted into organophosphorous N-heterocyclic vinyl polymers. The synthesized vinyl polymers were characterized using, FTIR, NMR and Mass spectral studies. Results of the spectral studies were well supported the formation of the compounds. Thermal stability have also been studied using TGA.

Main-chain liquid crystalline ionomers with a nonplanar ionic segment

At the presence of the physical crosslinking of ionic groups, tensile properties of the liquid crystalline ionomer were improved greatly.

Interfacial polycondensation method used in the synthesis of polymers containing phosphorus in the main chain

Polyphosphoesters gained importance especially due to their use as flame retardants and as biocompatible and biodegradable materials for medicine and in the pharmaceutical industry. This paper presents the results obtained by our research group in the synthesis of polyphosphoesters by interfacial polycondensation. This reaction is rapid and irreversible polymerization at the interface between a phase containing one difunctional intermediate and another phase containing a complementary difunctional reactant. Different methods like liquid–liquid, vapor–liquid or solid<uni-2013;liquid were used in the synthesis of polyphosphates of polyphosphonates using aliphatic/aromatic phosphoric/phosphonic dichlorides and different diols. Aqueous NaOH, or tripotasium phosphate were used as bases. In almost all cases a catalyst is not needed.

Synthesis of new phosphorus-containing (co)polyesters using solid-liquid phase transfer catalysis and product characterization

This paper is directed towards the development of safe, and thermally stable solid polymer electrolytes. Linear phosphorus-containing (co)polyesters are described, including their synthesis, thermal analysis, conductivity, and non-flammability. Polycondensation of phenylphosphonic dichloride (PPD) with poly(ethylene glycol) (PEG 12000) with and without bisphenol A (BA) was carried out using solid-liquid phase transfer catalysis. Potassium phosphate is used as base. Yields in the range of 85.0–88.0%, and inherent viscosities in the range of 0.32–0.58 dL/g were obtained. The polymers were characterized by gel permeation chromatography, FT-IR, ¹H- and ³¹P-NMR spectroscopy and thermal analysis. Their flammability was investigated by measuring limiting oxygen index values. The polymers are flame retardants and begin to lose weight in the 190 °C–231 °C range. Solid phosphorus- containing (co)polyesters were complexed with lithium triflate and the resulting ionic conductivity was determined. Conductivities in the range of 10⁻⁷–10⁻⁸ S cm⁻¹ were obtained.