Chinese Journal of Polymer Science

The adsorption of Fe(III) ions from aqueous solution by chitosan alpha-ketoglutaric acid (KCTS) and hydroxamated chitosan alpha-ketoglutaric acid (HKCTS) was studied in a batch adsorption system. Experiments were carried out as function of pH, temperature, agitation rate and concentration of Fe(III) ions. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and isotherm constants were determined. The Langmuir model agrees very well with experimental data. The pseudo-first-order and second-order kinetic models were used to describe the kinetic data and the rate constants were evaluated. The dynamical data fit well with the second-order kinetic model. The pseudo second-order kinetic model was indicated with the activation energy of 19.61 and 7.98 kJ/mol for KCTS and HKCTS, respectively. It is suggested that the overall rate of Fe(III) adsorption is likely to be controlled by the chemical process. Results also showed that novel chitosan derivatives (KCTS and HKCTS) were favorable adsorbents.

Microporous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membranes following supercritical CO₂ induced phase separation process were prepared using four solvents. The solid electrolytes of PVDF-HFP were formed by microporous PVDF-HFP membranes filled and swollen by a liquid electrolyte. The effect of the solvents on the morphology and structure, electrolyte absorptions and lithium ionic conductivity of the activated membranes were investigated. It was approved that all the membrane had the similar "sponge-like" and asymmetric structure when different solvent was used. As the mutual affinity between solvent and supercritical CO₂ decreased, the membrane porosity and the average pore diameter increased. The PVDF-HFP membrane with porosity at 88% and pore size at 10 μm were successfully prepared. The uptake of electrolyte solution and lithium ionic conductivity could reach 487 wt% and 3.09 × 10^-3 S/cm respectively for obtained membrane.

Several PVP-stabilized colloidal platinum metals nanoparticles have been synthesized and characterized by FTIR and TEM. Comparing with the pure PVP, carbonyl groups of PVP in the mixture of PVP and the metal precursors or in the PVP-stabilized metal nanoparticles have obvious peak shifts in FTIR spectra. The peak shifts reveal the interaction between PVP and the metal species. The interaction between PVP and metal precursors has effect on the formation of the colloidal metal nanoparticles. Strength of the interaction between PVP and metal nanoparticles has direct influence on the stability and the size of the PVP-stabilized metal nanoparticles. Therein, species of the metal precursors and amount of the stabilizer are main factors on the strength of the interaction.

The interaction of poly(ethylene oxide) (PEO) with the ionic surfactants, sodium dodecylsulfate (SDS) and cetyltrimethylammonium chloride (CTAC) respectively, in aqueous solutions containing a certain concentration of NH₄Cl, is studied by the viscosity measurement. It has been found that the ion-dipole interaction between PEO and ionic surfactants is changed considerably by the organic salt. For anionic surfactant of SDS, the addition of NH₄Cl into solution strengthens the interaction between PEO and the headgroup of SDS. On the other hand, for cationic surfactant of CTAC, the interaction between PEO and the headgroup of CTAC is screened significantly by NH₄Cl dissolved in solution. These findings may potentially be attributed to the negative property of the oxygen group of the PEO chain. In the presence of NH₄Cl, the cationic ions of the organic salt bind to the oxygen group of the PEO chain so that PEO can be referred to as a pseudo-polyelectrolyte in solution.

A group of heterogeneous latexes poly(butyl acrylate)/poly(styrene-co-methyl methacrylate) (PBA/P(St-co-MMA)) were prepared by a semi-continuous seeded emulsion polymerization process under monomer starved conditions. The glass transition temperature (T_g) and the mechanical properties of the film formed from the composite latex changed with the evolution of the particle morphology. A photon transmission method was used to monitor the phase structure evolution of films which were prepared from core-shell PBA/P(St-co-MMA) latex at room temperature and annealed at 383 K above T_g of the polymers. In addition, the changes of the surface of the film formed from the composite latex with time at 383 K were observed by AFM. The evidence illustrated that the film formed from the core-shell latex particles was metastable. The rearrangement of the phases could occur under proper conditions.

A new polymer, poly(imino isophthaloyl imino (2,4,8,10-tetraoksoaspiro [5,5] undekan-3,9-dipropylene)) [poly(IPIT)] was synthesized by an interfacial polycondensation reaction. The characterization of poly(IPIT) was conducted by using FT-IR, ¹³C-NMR, TG and DTA techniques. The kinetics of the thermal degradation of poly(IPIT) was investigated by thermogravimetric analysis at different heating rates. TG curves showed that the thermal decomposition of poly(IPIT) occurred in three stages. The apparent activation energies of thermal decomposition for poly(IPIT), as determined by the Tang method (TM), the Flynn-Wall-Ozawa method (FWO) and the Kissinger-Akahira-Sunose method (KAS) are 58.09, 57.7 and 61.0 kJ/mol for the first stage decomposition, 106.1, 105.6 and 109.8 kJ/mol for the second stage decomposition, and 138.1, 137.5 and 141.4 kJ/mol for the third stage decomposition, respectively.

Di(4-bromophenyl)ketone and various aromatic diamines as the monomers, a series of novel poly(imino ketone)s (PIKs) have been synthesized via palladium-catalyzed aryl amination, which is Hartwig-Buchwald polycondensation reaction. The structures of PIKs are characterized by means of elemental analysis, FT-IR, ¹H-NMR and UV-Vis spectroscopy. The results show a good agreement with the proposed structure. The general properties of PIKs are studied by DSC, TG and wide-angle X-ray diffraction, the solubility behavior is measured at polymer concentration 5 mg·mL^-1. It is obvious that PIKs show high glass transition temperature (T_g > 220°C), good thermal stability with high decomposition temperatures (T_D > 480°C) and excellent solubility.

The purpose of this study is to investigate the effect of composition poly(D,L-lactide-co-glycolide)/poly(ε-caprolactone) (PLGA/PCL) blending on the morphology, shrinkage and degradation behaviors of the electrospun fibers. With the increase of PLGA content in the composite fibers, the average diameter of the electrospun fibers increased from 1.35 μm to 1.95 μm. The serious shrinking of the electrospun PLGA meshes could be circumvented by adding 20% PCL in the fibers, resulting from the semi-crystalline nature of PCL. The degradation rate of the electrospun meshes could be modulated by PLGA/PCL composition. In addition, the electrospun meshes containing 20% PCL displayed stable dimensional morphology with degradation.

The preparation process-dependent phase morphology of blends composed of nylon 6 and acrylonitrile-butadiene-styrene (ABS) over a composition range of 30-70 wt% using a styrene-maleic anhydride (SMA) copolymer as the compatibilizing agent with a constant content (5phr) was investigated. The results of the scanning electron microscope (SEM) observation revealed that compared with the binary blends of nylon 6 and ABS, the existence of SMA caused a composition shift of phase inversion to a higher weight fraction of nylon 6 when ABS was blended with the preblended nylon 6/SMA blend, while the co-continuous structures could be observed over a considerably narrower composition range when nylon 6 was blended with the pre-blended ABS/SMA blend. An examination through dynamic mechanical analysis (DMA) tests confirmed the results obtained with SEM. It is found that near the phase inversion region a remarkable change in the dynamic storage modulus (G′) and the loss tangent (tanδ) appears. Moreover, the influence of blending sequence on the size of dispersed particles has been probed for uncompatibilized and compatibilized blends of nylon 6 and ABS over a wide range of compositions below or beyond the phase inversion points. For the blends of ABS dispersed in a nylon 6 matrix, little discernible effects of blending sequence on particle size could be observed. Furthermore, there exists a significant difference in morphologies of the blends prepared by nylon 6 particles dispersing in a ABS matrix in cases of different blending sequences used. Some possible factors responsible for the above asymmetric behaviors have been proposed.

The copolymerization of dibenzofuran (DBF) and 3-methylthiophene (MeT) was successfully achieved electrochemically by direct anodic oxidation of the monomer mixtures in boron trifluoride diethyl etherate. The effects of applied polymerization potential and the monomer concentration ratios on the copolymerization were investigated by linear sweep voltammetry and cyclic voltammetry (CV). The structure of copolymer films were investigated by UV-Vis, infrared spectroscopy, thermal analysis. As-formed novel copolymers own both the advantages of poly(3-methylthiophene) and poly(dibenzofuran), that is, good redox activity, good thermal stability. Fluorescence spectra suggested that emission spectrum of copolymer films was blue-shifted in contrast to that of PDBF film.

An amorphous, colorless, and highly transparent star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized from the poly(ethylene glycol) (PEG), pentaerythritol, and dichloromethane by Williamson reaction. FTIR and ¹H-NMR measurement demonstrated that the polymer repeating units were C[CH₂ - OCH₂O - (CH₂CH₂O)_m - CH₂O - (CH₂CH₂O)_n - CH₂O]₄. The polymer host held well mechanical properties for pentaerythritol cross-linking. The gel polymer electrolytes based on Lithium perchlorate (LiClO₄) and ethylene carbonate/propylene carbonate (EC/PC) were prepared and characterized by AC impedance spectroscopy and thermogravimetry (TG), the results showed thermal stability up to at least 150°C and ionic conductivity reaching 8.83 × 10^-4S·cm^-1 at room temperature. The gel polymer electrolytes were further evaluated in electrochromic devices (ECD) fabricated by transparent PET-ITO and electrochromic active viologen derivative films, and its excellent performance promised the usage of the gel polymer electrolytes as ionic conductor material in ECD.

Multi-scales relaxation processes of short fiber of a nematic liquid crystalline copolymer (LCP) in polycarbonate matrix were investigated. First, the structure relaxation of LCP was studied by rheology. The relaxation spectrum of the nematic liquid crystalline copolymer at 295°C was calculated from the combined dynamic modulus. There are three kinds of relaxation mechanisms for nematic liquid crystalline copolymer: the relaxation of chain orientation, the relaxation of deformed polydomains and the coalescence of polydomains (or the relaxation of textures). As the relaxation of chain orientation is very fast, we have not obtained the accurate relaxation time by rheological measurements. The relaxation of deformed polydomains takes about 50 s. Domain coalescence occurs after a much longer relaxation time (> 2400 s). Secondly, the shape relaxation of LCP short fiber in matrix was studied. During shape relaxation of short fiber in matrix, changes of inner structure in short fiber take place, which is characterized by the application of power spectrum of discrete Fourier transform (DFT). The aspect ratio b/a increases during shape relaxation of short fiber in matrix.

A novel approach for the surface modification of poly(vinylidene fluoride) (PVDF) membrane was successfully realized through alkaline treatment, UV-induced bromine addition, and followed by surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Chemical changes on the PVDF membrane before and after modification were analyzed with attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR) and X-ray photoelectron spectroscopy (XPS). Primary kinetic study revealed that the chain growth of poly(methyl methacrylate) (PMMA) from the PVDF surface is consistent with a "controlled" process.

The flame retardancy of aromatic thermotropic liquid crystal phosphorus-containing copolyester, TLCP, on PET was investigated. The results show that the presence of TLCP promotes char formation of the substrate and enhances thermal stability of char, hence delay its decomposition. SEM pictures show that the char formed from PET/TLCP is more compact, therefore is more resistant to fire and heat than that from pure PET. Evolved gas analysis by I.R measurements indicates that TLCP would decompose to produce phosphorus containing small molecular compounds in pyrolysis process. Phosphorus- containing volatile compounds are detected in gas pyrolytical products. It is suggested that TLCP could play an important role of flame retardancy in vapor phase. TLCP could inhibit the generation of combustible volatile in the pyrolytical process of PET, and therefore prevent the fire propagation during the combustion since combustible volatile is necessary for the generation of fire.

Urethane modified bismaleimide (UBMI) was synthesized by the reaction of maleic anhydride (MA) with NCO group terminated polyurethane prepolymer (PUP) in presence of acetone. The product was determined by infrared analysis. Then ultrasonic assistant process was introduced into the solvent removal of the prepolymer mixture of UBMI and PUP. Polyurethane-imide (PUI) elastomer was synthesized from the above PUP-UBMI prepolymer mixture by the infusion technology with 2,5-dimethyl-2,5-bis(tert-butylperoxy)-hexane (B25) as liquid initiator at 120°C. The thermal properties and stress-strain behavior of PUI elastomer was characterised by thermogravimetric (TG) analysis and tensile testing apparatus, respectively. Compared with pure polyurethane elastomer, the PUI elastomer composite showed the better thermal stability.