Poly(acrylic acid)(PAA)and graphene oxide-chitosan(GO-CS)composites were deposited on the surface of polypropylene(PP)microporous membrane to prepare poly(acrylic acid)/graphene oxide-chitosan(PAA/GO-CS),composite membrane by layer-by-layer assembly technology.The adsorption and separation effect of(PAA/GO-CS)n composite membrane for methylene blue and congo red in aqueous solution was inves-tigated.The structures of GO-CS complex and(PAA/GO-CS)n composite membrane were characterized by in-frared spectroscopy,thermogravimetric analysis and scanning electron microscope.Results show that(PAA/GO-CS)n composite membrane was successfully prepared and had stable thermochemical properties.The surface morphology and porosity of the composite membrane can be controlled by the number of assembled layers.The permeability of the composite membrane to methylene blue and congo red decreased with the increase of the number of assembled layers,and the interception rate increased with the increase of the number of assembled layers.The permeability of the composite membrane for methylene blue was 2761.3 L·m-2·h-1·bar-1,the re-tention rate was 91％,the adsorption rate was 39％.The permeability for congo red was 3068 L·m-2·h-1·bar-1,the reten-tion rate was 43％,the adsorption rate was 33％when assembled to 20 layers.The composite film has preferen-tial adsorption for positively charged cationic dyes.
Copolymers with varying molar ratios were created by initiating hydroxyethyl acrylate and maleic an-hydride monomers with ammonium persulfate.A capillary dilatometer was used to measure the conversion of copolymerization.The copolymer's composition curve was determined using acid-base titration,and the reactiv-ity ratios of hydroxyethyl acrylate to maleic anhydride were determined using the YBR method.According to the calculation results,r1(HEA)and r2(MA)were 2.3188 and 0.0272,respectively,indicating that hydroxyethyl acry-late should be slowly added to maleic anhydride in order to obtain a uniform copolymer.Finally,it can be ob-tained by potentiometric titration,the pKa1 and pK a2 values of copolymer with the molar feed ratio of 7∶3 are 4.33 and 7.59,respectively.
The rheology and crystallization behavior of thermal liquid crystalline polymer(TLCP)resin with monomer ratio of hydroxybenzoic acid(HBA)∶6-hydroxy-2-naphthoic acid(HNA)=73∶27 is investigated in this study.The effects of parameters including dynamic shear frequency,shear rate,temperature and time on the linear and nonlinear rheological behavior are firstly discussed.It is pointed out that the intrinsic rigid charac-teristic of TLCP molecule is the main reason for the solid-like behavior at low frequency range and the failure of Cox-merz rule.Then the isothermal and nonisothermal crystallization behavior of TLCP is investigated based on rheology measurement characterizations.It shows that the crystallization rate decreases significantly as the cool-ing rate declines from 10 ℃/min to 1.5 ℃/min for TLCP resin from nematic phase.In addition,the isothermal crystallization behavior of TLCP melt is controlled by homogeneous nucleation and the corresponding crystal growth is in a three dimensional way with an Avrami point value of around 4.Moreover,it is found that increas-ing the molecular weight of TLCP resin contributes to decreasing the crystallization ability but has no influence on the crystallization way.This report confirms that it is an effective tool to study the mechanism of TLCP crys-tallization behavior by monitoring the rheology behavior of TLCP resin during cooling process.
The copolymerization of ethylene oxide(EO),glycol methyl glycidyl ether(nGE)and allyl glycidyl ether(AGE)catalyzed by i-Bu3 Al/H3 PO4/DBU has been examined.The microstructures,thermal properties and molecular weights of the obtained polymers were characterized by nuclear magnetic resonance spectroscopy(NMR),gel permeation chromatography(GPC)and differential scanning calorimeter(DSC).The results showed that the i-Bu3Al/H3PO4/DBU catalyst serves as an excellent catalyst for the copolymerization of EO,nGE,and AGE to afford a family of ether chain modified poly(ethylene oxide).The obtained EO-nGE copoly-mers and EO-nGE-AGE terpolymers with controllable contents were conveniently obtained in 100％yield within 30 min by changing the feed ratio.The ether chain length of nGE has no effect on the copolymerization.The cross-linked copolymers were prepared using the EO-nGE-AGE terpolymer as precursors and 1,2-ethanedithiol as a crosslinking agent.The properties of copolymers revealed that the ether chain length and content,crosslinking had a significant impact on the conductivity and mechanical properties of copolymers.The copoly-mers with tetraethylene glycol methyl glycidyl ether(4GE)as a comonomer exhibited higher conductivity than that of diethylene glycol methyl glycidyl ether(2GE).With the increase of the content of 4GE in the EO-4GE copolymers,the conductivity increased,but the mechanical properties decreased.The appropriate crosslinking degree improved not only the mechanical properties but also conductivity.The cross-linked EO-4GE-AGE poly-mer electrolytes containing 39 mol％4GE and 2 mol％AGE showed the tensile strength and conductivity of 1.41 MPa and 9× 10-5 S·cm-1 at 30 ℃,respectively.
A novel 1,3-disubstitued indolyl ligand was designed and synthesized,and furtherly,a series of corre-sponding rare-earth metal complexes were obtained.The complexes were characterized by X-ray single crystal diffraction,nuclear magnetic resonance(NMR)spectroscopy,Fourier transform infrared(FTIR)spectroscopy as well as elemental analysis.The results indicated that the ligand coordinated to the metal in NCN tridentate mode to form a mononuclear penta-coordination geometry,adding two alkyl groups.The complexes could effi-ciently catalyze the isoprene polymerization with AlMe3 and[Ph3C][B(C6F5)4]as co-catalysts to obtain 1,4-cis polymer.
