Xiaowu Yang

Preparation and properties of waterborne cationic fluorinated polyurethane

Waterborne cationic fluorinated polyurethane (WCFPU) micro-emulsion was prepared by the reaction of isophorone diisocyanate (IPDI), polytetramethyleneether glycol (PTMG1000), 1,4-butanediol (BDO), N-methyldiethanolamine (MDEA), trimethylolpropane (TMP) and perfluoroalkylethyl octanol (FEOH), and then the films of the WCFPU were prepared. The influence on the mechanical properties and water absorption of the films, such as the molar ratio of NCO to OH, the dosage of MDEA, TMP and FEOH, was investigated. Their structure, morphology and heat performance were characterized by fourier transform infared spectrometer (FT-IR), dynamic light scattering (DLS), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and thermogravimetry (TG). The results revealed that the best mechanical properties and water resistance could be obtained under the condition that NCO/OH molar ratio was 1.25, w(TMP) was 1.1%, w(MDEA) was 7.29% and w(FEOH) was 22.3%. In addition, WCFPU was endowed with low surface energy of its film and the membrane surfaces had excellent water and oil repellency. Furthermore, the thermal stability of the waterborne cationic fluorinated polyurethane increased with the incorporation of perfluoroalkyl chain. And XRD, DSC and TG showed that micro-crystallinity of polyurethane increased with the increase of FEOH, which was benefit to the micro-phase seperation.

Preparation and Application of Amphoteric Polyacrylate Containing Long Hydrophobic Aliphatic Chain in the Presence of Poly(vinyl alcohol)

Amphoteric polyacrylate containing long hydrophobic aliphatic chain in the presence of poly(vinyl alcohol) (PVA) was synthesized. The influences of PVA on the properties of the emulsion and its film were investigated in details. In addition, the emulsion and the film were characterized by various examining methods. Furthermore, the applied properties of paper sized by amphoteric polyacrylate in the presence of poly (vinyl alcohol) were measured, in contrast to acrylic polymer prepared with the conventional low molecular weight emulsifier, the physical indexes were all improved.

Carboxymethyl fenugreek gum: Rheological characterization and as a novel binder for silicon anode of lithium-ion batteries

The rheology of carboxymethyl fenugreek gum (CFG) is characterized and applied it as a binder for the silicon anode of lithium-ion batteries (LIBs). First, a series of carboxymethyl fenugreek gum (namely CFG-1, CFG-2 and CFG-3) was prepared and characterized by Fourier transform infrared spectrophotometer and hydrogen nuclear magnetic resonance spectrometry studies. In rheological measurements, the CFG solutions show higher flowability, weaker viscoelastic behavior and better thixotropy than that of fenugreek gum (FG) solution. Furthermore, the higher degrees of substitution (DS) of CFG solutions lead to lower apparent viscosity and higher flow index, weaker elastic effect and smaller relaxation time, and higher viscosity recoverability than those obtained for lower DS of CFG solutions. In electrochemical measurements, the polar hydroxyl and carboxyl groups in the CFG skeleton chain provide bonding points between the CFG binders and the silicon electrode to produce binder-silicon bonds, which cause strong hydrogen bonding, and resulted in excellent electrochemical stability and specific capacity. The electrochemical performances were measured via the silicon electrodes with FG and CFG at 5 wt% content. As the DS is increased, the initial Coulombic efficiency can increase from 88.74% to 91.3%. When the electrode undergoes a volume change, the CFG binder with silicon electrodes can hold high capacity of above 1500 mAh/g after 200 charge-discharge cycles. Therefore, the carboxymethyl fenugreek gum as a binder may also be a novel extended binder-design, with applications for silicon anodes of LIBs.