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Synthesized Polymers (synthesized + polymer)
Selected AbstractsIn vitro degradability and stability of hydrophobically modified pH-sensitive micelles using MPEG-grafted poly(,-amino ester) for efficient encapsulation of paclitaxelJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Min Sang Kim Abstract Methoxypoly(ethylene glycol)-grafted poly(,-amino ester) was synthesized for the fabrication of pH-sensitive micelles, and these micelles were modified with deoxycholic acid to facilitate the hydrophobic interaction between the micellar core and paclitaxel. The micelle properties were studied by dynamic light scattering and fluorescence spectrometry. An in vitro degradation study showed that the synthesized polymers degraded hydrolytically within 24 h under physiological conditions. The stability of paclitaxel-loaded pH-sensitive micelles was evaluated in vitro. The introduced deoxycholic acid more stabilized the micelles at pH 7.4 compared to the micelles without modification. But the pH-sensitive region of the micelles was lowered from pH 6.8 to pH 5.8. These results indicate that pH-sensitive micelles with improved stability have great potential as hydrophobic drug carriers for tumor targeting. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Uptake of nicotine from suspension culture of Nicotiana tabacum by molecularly imprinted polymersJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2010Mohamed Salaheldin A. Abdelkader Abstract Objectives The aim was to use molecularly imprinted polymers (MIPs) for the selective recovery of nicotine in plant cell cultures. MIPs can selectively uptake nicotine from suspension cultures of N. tabacum, and therefore may be useful for improving levels of secondary metabolites in plant cell cultures. Methods Suspension cultures of N. tabacum were initiated from callus and maintained in liquid Murashige and Skoog (MS) media containing 3% w/v sucrose, 0.1 mg/l ,-naphthaleneacetic acid acid (NAA) and 0.25 mg/l kinetin. Tween 80 at 1% was used for permeabilisation of cell cultures. Pre-weighed XAD-2 and two types of synthesized polymers, MIPs (A and B with one and two functional monomers, respectively) and corresponding non-imprinted polymers (NIPs), A and B, were introduced aseptically into the permeabilised suspension cultures of N. tabacum, the nicotine contents of polymers were determined by gas chromatography and the adsorption yield of polymers were determined. Key findings Cell cultures of N. tabacum accumulated nicotine alkaloid intracellularly in varying levels, 6.8,14.9 mg/l fresh weight. MIPs were able to uptake 50,70% of released nicotine in suspension cultures of N. tabacum, whereas XAD-2 recovered only 30,40%. The total levels of accumulated nicotine were enhanced up to 20 mg/l by simultaneous use of Tween 80 and MIPs. Conclusions The findings indicate the potential use of MIPs to uptake nicotine from suspension cultures of N. tabacum, and increase productivity of secondary metabolites in plant cell cultures. [source] Electrochemical and optical properties of novel donor-acceptor thiophene-perylene-thiophene polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2008Sermet Koyuncu Abstract In this study, donor-acceptor type thiophene-perylene-thiophene monomers were synthesized and polymerized by both oxidative polymerization using FeCl3 as catalyst and the electrochemical process. UV,vis, FTIR, 1H NMR, and elemental analysis techniques were used for structural characterization. Thermal behaviors of these compounds were determined by using TGA system. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and electrochemical and optical band gap values were calculated by using the results of cyclic voltammetry and UV,vis measurements, respectively. The number,average molecular weight (Mn), weight,average molecular weight (Mw), and polydispersity index (PDI) values of synthesized polymers were determined by size exclusion chromatography. Conductivity measurements of these polymers were carried out by electrometer by using a four-point probe technique. The conductivity was observed to be increased by iodine doping. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1974,1989, 2008 [source] Preparation and characterization of chiral polyacrylates end-capped with bornyl groups in the side chainsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2004Jui-Hsiang Liu Abstract Chiral polyacrylates with bornyl end-capped side chains with four kinds of mesogenic moieties (azobenzene, biphenyl, benzoyloxy biphenyl, and phenyl benzoate) were prepared. The phase properties of the polymers were investigated with X-ray diffraction, differential scanning calorimetry, and polarizing optical microscopy. The thermogravimetric characteristics, the glass-transition temperatures and weight-average molecular weights, of the homopolymers were evaluated. The optical properties of the synthesized polymers in diluted solutions and in the thin-film state were also evaluated. The optical behavior of the composite films upon photoirradiation was investigated through the change in the transmittance of the probe light triggered by ultraviolet (365-nm) irradiation. Ultraviolet irradiation and heat treatment caused a reversible intensity change of the probe light at , = 400 nm. The shrinkage of the photoisomerization of the composite films was also investigated with atomic force microscopy. A spot contraction appeared on the surface when it was irradiated with a laser light spot. The contraction was recovered by heat treatment at 80 °C for 10 min. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1075,1092, 2004 [source] NLO Behavior of Polymers Containing Y-Shaped ChromophoresMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 17 2007Antonio Carella Abstract New polyurethanes containing Y-shaped chromophores, symmetrical derivatives of 4-(dicyanomethylene)-2-methyl-6-[p -(dimethylamino)styryl]-4H-pyran, have been prepared. The polymers show high glass transition temperatures (Tg) and a good thermal stability. SHG measurements on poled polymer films of the synthesized polymers have been carried out and a maximum d33 of 15 pm,·,V,1 has been found at 1,368 nm fundamental wavelength. Time stability measurements on the most active polymer have shown that after the initial fast relaxation, the d33 value remains constant at 80,°C for 60 d. [source] Acrylonitrile-Butadiene Rubber (NBR) Prepared via Living/Controlled Radical Polymerization (RAFT)MACROMOLECULAR RAPID COMMUNICATIONS, Issue 18 2010Andreas Kaiser Abstract In the current work we present results on the controlled/living radical copolymerization of acrylonitrile (AN) and 1,3-butadiene (BD) via reversible addition fragmentation chain transfer (RAFT) polymerization techniques. For the first time, a solution polymerization process for the synthesis of nitrile butadiene rubber (NBR) via the use of dithioacetate and trithiocarbonate RAFT agents is described. It is demonstrated that the number average molar mass, , of the NBR can be varied between a few thousand and 60,000,g,·,mol,1 with polydispersities between 1.2 and 2.0 (depending on the monomer to polymer conversion). Excellent agreement between the experimentally observed and the theoretically expected molar masses is found. Detailed information on the structure of the synthesized polymers is obtained by variable analytical techniques such as infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, and electrospray ionization-mass spectrometry (ESI-MS). [source] Low-Temperature Restructuring Processes in PolyhydrosilanesMACROMOLECULAR RAPID COMMUNICATIONS, Issue 13 2006Liviu Sacarescu Abstract Summary: This paper presents the structural influence of the SiH functionality on the physicochemical properties of polysilanes. New low-temperature restructuring processes were discovered using thermal analysis (TGA, DSC). Photoluminescent (FL) and X-ray photoelectron spectroscopy (XPS) measurements revealed the optoelectronic properties-chemical structure relationship of the synthesized polymers. Highly reactive SiH groups lead to restructuring of the main polysilane chain. [source] | ||||||||||