Home About us Contact
|
Home About us Contact | ||
|
|
||
Side Chain Length (side + chain_length)
Selected AbstractsEffects of Annealing on the Nanomorphology and Performance of Poly(alkylthiophene):Fullerene Bulk-Heterojunction Solar Cells,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2007H. Nguyen Abstract The evolution of nanomorphology within thin solid-state films of poly(3-alkylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester (P3AT:PCBM) blends during the film formation and subsequent thermal annealing is reported. In detail, the influence of the P3AT's alkyl side chain length on the polymer/fullerene phase separation is discussed. Butyl, hexyl, octyl, decyl, and dodecyl side groups are investigated. All of the P3ATs used were regioregular. To elucidate the nanomorphology, atomic force microscopy (AFM), X-ray diffraction, and optical spectroscopy are applied. Furthermore, photovoltaic devices of each of the different P3ATs have been constructed, characterized, and correlated with the nanostructure of the blends. It is proposed that the thermal-annealing step, commonly applied to these P3AT:PCBM blend films, controls two main issues at the same time: a),the crystallization of P3AT and b),the phase separation and diffusion of PCBM. The results show that PCBM diffusion is the main limiting process for reaching high device performances. [source] The synthesis of poly(3-hydroxybutyrate)- g -poly(methylmethacrylate) brush type graft copolymers by atom transfer radical polymerization methodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Hülya Arslan Abstract Brush type of poly (3-hydroxy butyrate), PHB, copolymer synthesis has been reported. Natural PHB was chlorinated by passing chlorine gas through PHB solution in CHCl3/CCl4 mixture (75/25 v/v) to prepare chlorinated PHB, PHB-Cl, with the chlorine contents varying between 2.18 and 39.8 wt %. Toluene solution of PHB-Cl was used in the atom transfer radical polymerization (ATRP) of methyl methacrylate, MMA, in the presence of cuprous bromide (CuBr)/2,2,-bipyridine complex as catalyst, at 90°C. This "grafting from" technique led to obtain poly (3-hydroxybutyrate)-g-poly(methylmethacrylate) (PHB- g -PMMA) brush type graft copolymers (cylindrical brush). The polymer brushes were fractionated by fractional precipitation methods and the , values calculated from the ratio of the volume of nonsolvent to volume of solvent of brushes were ranged between 2.8 and 9.5 depending on the molecular weight, grafting density, and side chain length of the brushes, while the , values of PHB, PHB-Cl, and homo-PMMA were 2.7,3.8, 0.3,2.4, and 3.0,3.9, respectively. The fractionated brushes were characterized by gel permeation chromatography, 1H-NMR spectrometry, thermogravimetric analysis (TGA), and differential scanning calorimetry techniques. PHB- g -PMMA brush type graft copolymers showed narrower molecular weight distribution (mostly in range between 1.3 and 2.2) than the PHB-Cl macroinitiator (1.6,3.5). PHB contents in the brushes were calculated from their TGA thermograms and found to be in range between 22 and 42 mol %. The morphologies of PHB- g -PMMA brushes were also studied by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Effects of chemical structure on the properties of carboxylate-type copolymer dispersant for coal-water slurryAICHE JOURNAL, Issue 9 2009Renfu Xu Abstract In this study, a series of carboxylate-type copolymer dispersants were prepared. The effects of chemical structures of the copolymer dispersants, including the molecular weight, kind, quantity and ratio of hydrophilic/hydrophobic groups, and side chain length, on the solid loading, apparent viscosity, zeta potential, rheological behavior, and stability of coal-water slurry (CWS) prepared from Dongtan, Yima, and Datong coals were systematically investigated. The dispersion performance of the copolymer can be improved by adjusting its chemical structures, and the dispersion mechanism was discussed. In addition, a high solid loading CWS with excellent stability toward settling can be achieved by means of the copolymer dispersant and carboxymethyl cellulose sodium salt (CMC-Na). Experiments have proved that the copolymer has the potential to be developed as a new high-effective dispersant for CWS. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis and characterization of a poly(GMA)-graft-poly(Z- L -lysine) graft copolymer with a rod-like structureJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2009You-Liang Tu Abstract This study applied the macromonomers and glycidyl methacrylate (GMA) to synthesize a series of the graft copolymers, poly(GMA)-graft-poly(Z- L -lysine), and investigated the conformation of the graft copolymer. The graft copolymers were synthesized with different GMA monomer ratios (28 to 89%) and different degrees of polymerization (DP) (8 to 15) of the poly(Z- L -lysine) side chain to analyze secondary structure relationships. Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and both wide angle and small angle X-ray scattering spectroscopy (WAXS, SAXS) were used to investigate the relationship between the microstructure and conformation of the graft copolymers and the different monomer ratios and side chain DP. In AFM images, n8-G89 (the graft copolymer containing 89% GMA units and the macromonomer DP is 8) showed tiny and uniform rod-like structures, and n14-G43 (the graft copolymer containing 43% GMA units and the macromonomer DP is 14) showed uniform rod-like structures. FTIR spectra of the graft copolymers showed that the variations of ,-helix and ,-sheet secondary structures in the graft copolymers relate to the monomer ratios of the graft copolymers. However, the X-ray scattering patterns indicated that the graft copolymer conformations were mainly dependent on the poly(Z- L -lysine) side chain length, and these results were completely in accordance with the AFM images. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4655,4669, 2009 [source] A Water-Soluble ,-Conjugated Polymer with up to 100 mg,·,mL,1 SolubilityMACROMOLECULAR RAPID COMMUNICATIONS, Issue 16 2007Huiping Wang Abstract A cationic water-soluble polyfluorene (P2) containing a high density of tetraalkylammonium side chains in polymer backbone was synthesized and characterized. The polymer shows excellent water solubility up to 100 mg,·,mL,1 as well as high photoluminescence (PL) quantum yield of 44% in water. The relatively high cationic density and appropriate side chain length of the polymer are the key factors to achieve such high water solubility. The reduction potential of P2 is decreased as compared with its neutral polymer, reflecting the enhanced electron injection abilities. The standard NPB/Alq3 device using such a polymer as the electron injection layer shows nearly three-fold enhancement in the electroluminescence (EL) efficiency. [source] Synthesis of 2-Fluoro N10 -Substituted Acridones and Their Cytotoxicity Studies in Sensitive and Resistant Cancer Cell Lines and Their DNA Intercalation StudiesARCHIV DER PHARMAZIE, Issue 11 2009Yergeri C. Mayur Abstract A series of 2-fluoro N10 -substituted acridone derivatives with varying alkyl side chain length with propyl, butyl substitution, and a tertiary amine group at the terminal end of the alkyl side chain were synthesized and screened against cancer cell lines SW 1573, SW 1573 2R 160 (P-gp substrate) which are non-small lung cancer cell lines, MCF-7, MCF-7/MR (BCRP substrate) are breast cancer cell lines, 2008 WT, 2008MRP1, 2008MRP2, 2008MRP3 are ovarian cancer cell lines, and human embryo kidney cell lines like HEK293, HEK293 MRP4, and HEK293 MRP5i. The propyl-series compounds showed lipophilicity in the range of 1.93 to 4.40 and the butyl series in the range of 2.37 to 4.78. The compounds 4, 7, and 8 showed good cytotoxicity against the 60 human cancer cell line panel of the National Cancer Institute, USA. The compounds 14 and 15 showed a better cytotoxicity in most of the cancer cell lines compared to other compounds tested. The DNA-binding properties of the compounds were evaluated based on their affinity or intercalation with CT-DNA measured with absorption titration. The compound 11 bearing planar tricyclic ring linked with a butyl methylpiperazino side chain showed the highest binding affinity with a binding constant (Ki) of 10.38×10 M,1. Evaluation of the compounds in cell lines with an overexpression of various multidrug resistance-related protein (MRP), P-glycoprotein (P-gp), or Breast Cancer Resistance Protein (BCRP) showed that all compounds are not substrates for any of these transporters. [source] Rheology control by modulating hydrophobic and inclusive associations of side-groups in poly (acrylic acid)ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Jie Wang Abstract In this article we demonstrated that the viscosities of modified poly (acrylic acid) (PAA) solutions were tunable by modulating the hydrophobic and inclusion association between alkyl groups and ,-cyclodextrin (,-CD) groups grafted to PAA. The viscosity can be controlled by changing the host,guest molar ratio, alkyl chain length, polymer concentration, salt concentration, pH value, temperature, or addition of native ,-CD. A viscosity maximum for inclusive polymer networks constructed by mixing hydrophobically modified PAA (HMPAA) and ,-CD,modified PAA (,-CDPAA) appeared at the alkyl : ,-CD molar ratio of 1:1, which implies the inclusion association between HM and ,-CD grafts is binary. Longer side chain length or higher polymer concentration led to higher viscosity for aqueous HMPAA solution with only hydrophobic association or its mixture with ,-CDPAA with inclusion association. Monotonically increasing the ionic strength or pH value resulted in a viscosity maximum due to the competition between electrostatic repulsion and hydrophobic or inclusive association. The hydrophobic interactions of alkyl groups could be masked by native ,-CD, and the networks of HMPAA and ,-CDPAA mixture deconstructed upon addition of native ,-CD molecules. The storage modulus and loss modulus of hydrophobic HMPAA and inclusive HMPAA + ,-CDPAA solutions obey time,temperature superposition. The horizontal and vertical temperature shift factors obeyed a simple-exponential Arrhenius relationship, where the activation energies for hydrophobic association system were found to be 3.4 and , 12.1 kJ/mol, and for inclusive association system 53.9 and , 2.9 kJ/mol, respectively. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] The effect of the side chain length of Asp and Glu on coordination structure of Cu2+ in a de novo designed proteinBIOPOLYMERS, Issue 11 2009Daigo Shiga Abstract Metal ions in proteins are important not only for the formation of the proper structures but also for various biological activities. For biological functions such as hydrolysis and oxidation, metal ions often adopt unusual coordination structures. We constructed a stable scaffold for metal binding to create distorted metal coordination structures. A stable four stranded ,-helical coiled-coil structure was used as the scaffold, and the metal binding site was in the cavity created at the center of the structure. Two His residues and one Asp or Glu residue were used to coordinate the metal ions, AM2D and AM2E, respectively. Cu2+ bound to AM2D with an equatorial planar coordination structure with two His, one Asp, and H2O as detected by electron spin resonance and UV spectral analyzes. On the other hand, Cu2+ had a slightly distorted square planar structure when it bound two His and Glu in AM2E, due to the longer side-chain of the Glu residue as compared to the Asp residue. Computational analysis also supported the distorted coordination structure of Cu2+ in AM2E. This construct should be useful to create various coordinations of metal ions for catalytic functions. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 907,916, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | |||||||||||||