Advanced Materials Research Vols. 554-556

Abstract: Properties of corn starch dissolved in NaOH/urea aqueous solutions were studied in this research, and NaOH/urea at different ratios in aqueous system was used to treat corn starch (CS). NaOH/urea breaks down the structure of CS, resulting in chemical degradation. After degradation, the change of molecular weight was analyzed by GPC-MALLS. The degraded CS (DS) and native CS(NS) were grafted with acrylic acid and compared in FTIR and both DS and NS were successfully grafted with AA.

Abstract: A novel polyacrylonitrile (PAN)-based fluorescence probe was prepared by chemically combining the aminoanthraquinone as a fluorescent group with the PAN chains. It is found that the -C≡N group in PAN chains can affect the photolysis of anthraquinone groups. The results show that the conformational state and aggregation behavior of PAN can be monitored by observing the intensity variation in fluorescence emission spectrum for PAN-AAQN solutions.

Abstract: A new poly(ester-imide-ether) (PEIE) was prepared by melt polymerization from 1,4-butanediol(BD), polytetrahydrofuran diol (PTMG) and a novel imide dicarboxylic acid monomer which was synthesized from 3,3',4,4'-biphenyltetracarboxylic di-anhydride(BPDA) and glycine acid(GLY). The structure, thermal behaviour and elastic recovery of polymer were characterized by FT-IR. thermogravimetric analysis (TGA), differential scanning calorimetry thermograms (DSC) and laboratory stretching machine. The results showed this polymer has excellent thermal stability, 5 % weight loss temperature was at 354°C. Meanwhile, the DSC curve showed that glass-transition temperature and crystallization temperature of the polymer were at -30 °C and 160 °C, respectively. The excellent elastic recovery was still displayed at low temperature.

Abstract: Biocompatible quaternary chitosan/sodium alginate multilayer microcapsules were prepared by layer-by-layer (LBL) self-assembly on the template of monodispersed melamine formaldehyde resin microspheres (MF). The process of self-assembly was monitored by measuring the surface zeta-potential of colloidal particles. The particle size was determined by digital light scattering (DLS) after each deposition, and the average thickness of monolayer film was revealed to be 3.9 nm. Using rhodamine B-labeled quaternary chitosan as the positive polyelectrolyte and sodium alginate as the negative polyelectrolyte, self-assembled multilayer microcapsules with strong red-light emitting were obtained and observed with fluorescence microscope. The fluorescent microcapsules self-assembled from the biocompatible natural polysaccharides may be potentially applied in drug delivery and fluorescence diagnosis.

Abstract: A new one-dimensional [CuC₁₆ H₁₈ N₄O₄S]n(1) was synthesized by the self-assembly of a ligand 2,5-thiophenediformates, 3,5-dimethylpyrazole and copper(II), and characterized by elemental analysis, IR and single-crystal X-ray diffraction. 1 crystallizes in monoclinic, space group C2/c with unit cell parameters, a=18.6156(4), b=5.96110(10), c= 18.1598(4)Å, =115.467(2)°, Z=4, V=1819.37(7)Å3, Mr = 425.94, Dc = 1.555g/cm3, μ=1.345mm-1, and F(000)= 876. The final R and wR are 0.0328 and 0.0816 for 7611 observed reflections with I>2σ(I). 1 shows an infinite 1-D polymeric chain structure based on the repeated basic units Cu(II)(3,5-dimethylpyrazole)2(2,5-thiophene diformate). The Cu(II)center acts as the joint of the unit, and is coordinated in a slightly distorted octahedral geometry comprised of four O atoms from two different 2,5-thiophenediformate ligands and two N atoms of two trans 3,5-dimethylpyrazole ligands.

Abstract: Polysulfone microcapsules containing ionic liquid were successfully prepared in a two stage process and the influence factors on the microcapsules’ diameter had also been investigated. The result shows that the diameter of micro tube and the concentration of aqueous solution both have effect on the diameter of microcapsules. And the concentration of ionic liquid in dichloromethane can influence the microencapsulation capacity. This method to produce microcapsules is easy to control.

Abstract: In this paper, needle-shape insulation defect was made in XLPE cable samples. With high-voltage and high-frequency accelerated aging, water tree was formed inside XLPE layer. One group of the samples was injected siloxane catalyzed by isopropoxide for rejuvenation, and the breakdown voltage was significantly greater than new samples. Nano-inorganic particles were observed by scanning electron microscope (SEM) inside the breakdown channels of rejuvenated samples. The insulation enhancement mechanism is described in this paper based on the new discovery, that the insulating property of cables is enhanced by the nano-inorganic particles, because of its ability to inhibit the partial discharge damage inside the water tree channel.

Abstract: Poly (vinyl chloride) (PVC)/halloysite nanotubes (HNTs) nanocomposites had been prepared by melt blending. The heat distortion temperature (HDT) and vicat softening temperature (VST) of nanocomposites increased with increasing HNTs feed content. Cone calorimetry was used to measure the smoke evolution and fire properties. The addition of HNTs leaded to a remarkable reduction in the smoke production rate, the total smoke production and the peak heat release rate.

Abstract: Phase diagram of aqueous two-phase system (ATPS) composed of polyethylene glycol (PEG) and gelatin is of paramount importance for the application of such system in microencapsulation of bioactive compounds. Phase separation of PEG/gelatin aqueous solution was investigated in the present work and the phase diagram of resultant ATPS was reported for the first time. The results show that phase separation will happen if the solid content of PEG/gelatin aqueous solution is higher than a critical value, resulting in an ATPS. The resultant ATPS consists of a low-density phase enriched in PEG and a dense phase enriched in gelatin. The phase compositions of the resultant ATPS were determined accurately using the method developed. The phase diagrams obtained show that higher solid content is required for the phase separation of PEG10,000/gelatin aqueous solution when compared with that of PEG20,000/gelatin one. And PEG is found to be more hydrophilic when compared with gelatin.

Abstract: Hydroxyl-terminated poly(vinylbenzyl chloride) (PVBCOH) were synthesized using nitroxide-mediated controlled radical polymerization. Then, PVBCOH was used as a macro-initiator for ring-opening polymerization of lactide (LA) in the presence of stannous octanoate (Sn(Oct)₂) as a catalyst. The structures, molecular weights and polydispersity index (PDI) of PVBCOH and PVBC-b-PLA were characterized by 1H-NMR, and GPC, respectively. The results indicated that PDI of PVBCOH and PVBC-b-PLA was 1.63 and 1.27, respectively. Moreover, the molecular weight and PDI of PVBCOH and PVBC-b-PLA could be well tuned by changing monomer-to-initiator ratio.