Synthesis and Molecular Structure of (E)-1- (Morpholino)-2-(thiomethyl)-2-phenylvinylphosphonate

The title compound 2 (C15H22NO4PS, Mr = 343.38) was prepared by the reaction of α-benzoylthioformmorpholine 1 with trimethyl phosphite. The crystal is of monoclinic, space group P21/c with a = 14.906(2), b = 8.4711(12), c = 13.343(2) ?, β = 96.761(4)o, Z = 4, V = 1673.1(5) ?3, Dc = 1.363 g/cm3, μ(MoKα) = 3.06 cm-1, F(000) = 728, the final R = 0.0590 and wR = 0.1740 for 3036 observed reflections (I > 2σ(I)). X-ray analysis revealed that the interatomic distance of C(5)–C(6) is 1.353(4) ?, indicating it is a normal C=C double bond. The P(1) atom takes a distorted tetrahedral geometry, and the morpholine ring adopts a chair conformation. The morpholino group is located at the 1-position of vinylphosphonate, and the phenyl and thiomethyl groups at the 2-position.

Thermotolerant and fireproof gel polymer electrolyte toward high-performance and safe lithium-ion battery

Poly(ethylene oxide)(PEO)and its derivatives based gel polymer electrolytes(GPEs)are severely limited in advanced and safe lithium-ion batteries(LIBs)owing to the intrinsically high flammability of liquid electrolytes and PEO.Directly adding flame retardants to the GPEs can suppress their flammability and thus improve the safety of LIBs,but results in deteriorative electrochemical performance.Herein,a novel GPE with chemically bonded flame retardant(i.e.diethyl vinylphosphonate)in cross-linked polyethylene glycol diacrylate matrix,featuring both high-safety and high-performance,is designed.This as-prepared GPE storing the commercial 1 mol L^(-1) LiPF6 electrolyte resists high temperature of 200℃and cannot be ignited as well as possesses a high ionic conductivity(0.60 m S cm^(-1))and good compatibility with lithium.Notably,the LiFePO_(4)/Li battery with this GPE delivers a satisfactory capacity of 142.2 m A h g^(-1) and a superior cycling performance with a capacity retention of 96.3%and a coulombic efficiency of close to 100%for 350 cycles at 0.2 C under ambient temperature.Furthermore,the battery can achieve steady charge–discharge for 100 cycles with a coulombic efficiency of 99.5%at 1 C under 80℃and run normally even at a high temperature of 150℃or under the exposure to butane flame.Differential scanning calorimetry manifests significantly improved battery safety compared to commercial battery systems.This work provides a new pathway for developing next-generation advanced LIBs with enhanced performance and high safety.

Study on the microcosmic superlubricity mechanism of PVPA affected by metal cations

Hydrophilic polymer coatings on artificial implants generate excellent tribological properties.The friction properties of polymer coatings are affected by salt ion factors.Herein,the atomic force microscopy(AFM)was used to show that the superlubricity was achieved between poly(vinylphosphonic acid)(PVPA)-modified Ti6Al4V and polystyrene(PS)microsphere probe lubricated with monovalent salt solutions(LiCl,NaCl,KCl,and CsCl).Considering that adhesion is an important cause of friction changes,the AFM was further utilized to obtain adhesion between friction pairs in different salt solutions.The results indicated that the larger the cation radius in the lubricant,the smaller the adhesion,and the lower the friction coefficient of the PVPA coating.The electrostatic interaction between the PVPA and one-valence cations in lubricants was analyzed by the molecular dynamics(MD)simulation as it was found to be the main influencing factor of the adhesion.Combined analysis results of friction and adhesion indicated that by adjusting the size of cation radius in lubricant,the adhesion between the tribo-pairs can be changed,and eventually the magnitude of friction can be affected.This study opens up a new avenue for analyzing the friction characteristics of hydrophilic polymer coatings from the perspective of intermolecular forces.

Investigation of the mechanisms for stable superlubricity of poly(vinylphosphonic acid) (PVPA) coatings affected by lubricant

The stability of the tribological properties of polymer coatings is vital to ensure their long term use.The superlubricity of the poly(vinylphosphonic acid) (PVPA)-modified Ti6A14V/polytetrafluoroethylene (PTFE)interface can be obtained when lubricated by phosphate-buffered saline (PBS,pH =7.2),but not when lubricated by deionized water and ethanol.Therefore,the mechanisms for the superlubricity of PVPA coatings affected by lubricant were investigated in detail.The stability of the PVPA coatings and their compatibility with the lubricant are critical factors in realizing ideal tribological properties of PVPA coatings.Robust PVPA coatings are stable under a wide range of pH values (6-10) using PBS as the basic solution,and are also characterized by superlubricity.The hydrolysis kinetics of phosphate anhydride is the main reason for the pH responses.In addition,along with stability,PVPA coatings exhibit different friction coefficients in salt solutions which are composed of various ions,which indicates that the compatibility between PVPA coatings and the lubricant can be used to regulate the superlubricity properties.Based on a fundamental understanding of the mechanism of surperlubricity by considering the effects of the lubricant,PVPA coatings with stability and perfect tribological performance are expected to be applied in more aspects.

Flame-retardant Coating by Alternate Assembly of Poly(vinylphosphonic acid) and Polyethylenimine for Ramie Fabrics

A novel intumescent flame retardant coating, consisting of poly（vinylphosphonic acid） （PVPA） as the acid source and branched polyethylenimine （BPEI） as the blowing agent, was constructed on the surface of ramie fabrics by alternate assembly to remarkably improve the flame retardancy of ramie. The PVPA/BPEI coating on the surface of individual fibers of ramie fabric pyrolyzes to form protective char layer upon heating/burning and improves the flame retardancy of ramie. Thermogravimetric analysis reveals that the PVPA/BPEI-coated ramie fabrics left as much as 25.8 wt% residue at 600 ~C, while the control （uncoated） fabric left less than 1.4 wt% residue. Vertical flame test shows that all PVPA/BPEI-coated fabrics have shorter after-flame time, and the residues well preserved the original weave structure and fiber morphology, whereas, the uncoated fabric left only ashes. Microscale combustion calorimetry shows that the PVPA/BPEI coatings greatly reduce the total heat release by as much as 66% and the heat release capacity by 76%, relative to those of the uncoated fabric.