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Monomer Ratios (monomer + ratio)
Selected AbstractsSynthesis, characterization, mechanical properties and biocompatibility of interpenetrating polymer network,super-porous hydrogel containing sodium alginatePOLYMER INTERNATIONAL, Issue 12 2007Lichen Yin Abstract In this investigation an interpenetrating polymer network,superporous hydrogel containing sodium alginate (IPN-SPHAlg) was synthesized. The morphology of the polymer was characterized using scanning electron microscopy, light images and porosity, and the polymer was further examined by swelling ratio, mechanical strength and biocompatibility. The results indicated that the IPN-SPHAlg possessed both large numbers of interconnected pores and an interpenetrating network. The swelling ratio of IPN-SPHAlg was lower than that of the superporous hydrogel (SPH) and it decreased as the sodium alginate/monomer ratio increased. The IPN-SPHAlg exhibited pH responsiveness and salt-sensitive properties. Compared to SPH and SPH composites, the mechanical strength of IPN-SPHAlg was significantly enhanced. Thiazolyl blue assay on AD293 cells, in situ lactate dehydrogenase assay and morphological study of rat intestine showed that the polymer induced no significant cell or mucosal damage. The fast swelling, good mechanical properties, pH sensitivity and biocompatibility of the IPN-SPHAlg suggested it as a potential candidate in the field of drug-delivery systems. Copyright © 2007 Society of Chemical Industry [source] Parameters governing reproducibility of flow properties of porous monoliths photopatterned within microfluidic channelsELECTROPHORESIS, Issue 14 2010Mei He Abstract We report the patternability as well as the reproducibility and stability of flow resistance of polymer monolithic beds photopatterned within microfluidic channels as a function of initial reagent composition and preparation conditions. 2-Hydroxyethyl methacrylate and ethylene dimethacrylate-based polymer monoliths were selectively photopatterned within microchannels and their flow resistance was evaluated using a photobleaching, TOF linear flow rate measurement method developed in our lab. This measurement technique was found to be significantly more informative for columns formed in microfluidic channels compared with bulk monolith characterization by mercury intrusion porosimetry. 1-Octanol was determined to provide sharp bed edge formation and relatively low flow resistance by photopatterning relative to other porogenic solvents. Compared with literature formulations which did not achieve good flow stability and reproducibility from batch to batch, using 2-hydroxyethyl methacrylate, ethylene dimethacrylate and 1-octanol as porogenic solvents, less than 4% RSD was achieved in flow stability over 7 days for monoliths prepared with 60,80% crosslinker(monomer+crosslinker) ratio. Column-to-column variation of 5% RSD was obtained in this composition range. These results demonstrate that photopatterning of uniform polymer monolithic beds, which is critical for applications in multiplexed microfluidic systems, requires careful attention to the parameters that affect reproducibility, specifically the porogenic solvent choice and the crosslinker to monomer ratio. [source] Thermal Sensitivity of tert -Butyloxycarbonylmethyl-Modified Polyquats in Condensed Phase and Solubility Properties of Copolymers with N -IsopropylacrylamideMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2010Nina Gonsior Abstract The synthesis of the easily decomposable ionic monomer 2- tert -butoxy- N -[2-(methacryloyl-oxy)ethyl]- N,N -dimethyl-2-oxoethanammonium chloride (3) via thermally induced syn-elimination of a tert -butyl ester group was realized simply by mixing N,N -dimethylaminoethyl methacrylate (1) and tert -butyl chloroacetate (2) at ambient temperature without solvent. The obtained salt was polymerized via free radical polymerization. The decomposition and foaming via iso -butene formation takes place by heating up to about 160,°C. IR, DSC, TGA, and GC/MS measurements were performed to follow this pyrolysis reaction. Furthermore, the copolymerization of 3 with N -isopropylacrylamid (NiPAAm, 5) was carried out with different monomer ratios. Molar mass distributions were measured using an asymmetrical flow field-flow fractionation (aFFFF) system. The obtained copolymers 6,10 exhibit lower critical solution temperature (LCST) behaviour in water with cloud points at different temperatures depending on the monomer ratio. [source] AB2 Functional Polyesters via Ring Opening Polymerization: Synthesis and CharacterizationMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2009Ingrid W. Velthoen Abstract Aliphatic AB2 functional polyesters were conveniently prepared by the ring opening polymerization of , -caprolactone and L -lactide in the presence of the AB2 functional initiator 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) and Sn(Oct)2 as the catalyst. In L -lactide polymerization, both bis-MPA hydroxyl groups initiated the polymerization reaction, but for , -caprolactone polymerization this depended on the monomer to initiator to catalyst ratio. Initiation at two hydroxyl groups occurred at high monomer to initiator ([M]/[I]) ratio and at high Sn(Oct)2 to monomer ratio. The melting temperatures of the AB2 -functional PLLA and PCL polymers were comparable to linear polymers with a equal to the per arm in the polymer. [source] Study on superabsorbent composite XXV.POLYMER COMPOSITES, Issue 4 2010Synthesis, characterization, swelling behaviors of poly(acrylic acid- co - N -acryloylmorpholine)/attapulgite superabsorbent composites In this work, a novel poly(acrylic acid- co - N -acryloylmorpholine)/attapulgite superabsorbent composite was prepared by graft copolymerization among acrylic acid, N -acryloylmorpholine and attapulgite in aqueous solution, using N,N, -methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The result from FTIR spectra showed that OH of attapulgite participated in graft copolymerization with acrylic acid and N -acryloylmorpholine. Proper monomer ratio and atapulgite content could form a loose surface, and improve reswelling ability and initial swelling rate. The buffer action of the COOH and COO, groups in the superabsorbent composite keeps the water absorbency a rough constant in the pH range of 4.4,9.6. Both polarity and structure of an organic solvent are responsible for the phase transition point of the superabsorbent composite. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [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] Synthesis and characterization of block copolymers from 2-vinylnaphthalene by anionic polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2002Faquan Zeng Abstract The anionic polymerization of 2-vinylnaphthalene (2VN) has been studied in tetrahydrofuran (THF) at ,78 °C and in toluene at 40 °C. 2VN polymerization in THF, toluene, or toluene/THF (99:1 v/v) initiated by sec -butyllithium (sBuLi) indicates living characteristics, affording polymers with predefined molecular weights and narrow molecular weight distributions. Block copolymers of 2VN with methyl methacrylate (MMA) and tert -butyl acrylate (tBA) have been synthesized successfully by sequential monomer addition in THF at ,78 °C initiated by an adduct of sBuLi,LiCl. The crossover propagation from poly(2-vinylnaphthyllithium) (P2VN) macroanions to MMA and tBA appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution of the resulting block copolymer is narrow (weight-average molecular/number-average molecular weight < 1.3). Block copolymers with different chain lengths for the P2VN segment can easily be prepared by variations in the monomer ratios. The block copolymerization of 2VN with hexamethylcyclotrisiloxane also results in a block copolymer of P2VN and poly(dimethylsiloxane) (PDMS) contaminated with a significant amount of homo-PDMS. Poly(2VN- b -nBA) (where nBA is n -butyl acrylate) has also been prepared by the transesterification reaction of the poly(2VN- b -tBA) block copolymer. Size exclusion chromatography, Fourier transform infrared, and 1H NMR measurements indicate that the resulting polymers have the required architecture. The corresponding amphiphilic block copolymer of poly(2VN- b -AA) (where AA is acrylic acid) has been synthesized by acidic hydrolysis of the ester group of tert -butyl from the poly(2VN- b -tBA) copolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4387,4397, 2002 [source] Lipase-Catalyzed Synthesis and Properties of Poly[(12-hydroxydodecanoate)- co -(12-hydroxystearate)] Directed towards Novel Green and Sustainable ElastomersMACROMOLECULAR BIOSCIENCE, Issue 1 2008Hiroki Ebata Abstract Novel green and sustainable elastomers having both good biodegradability and chemical recyclability properties were designed and synthesized using potentially biobased materials and lipase as an environmentally benign catalyst. High molecular weight poly[(12-hydroxydodecanoate)- co -(12-hydroxystearate)] [poly(12HD- co -12HS)] samples with varying monomer ratios were prepared by the polycondensation of 12-hydroxydodecanoic acid and methyl 12-hydroxystearate using immobilized lipase from Candida antarctica (IM-CA) in toluene in the presence of molecular sieves 4A at 90,°C. Although poly(12HD) is a highly crystalline polyester having a melting temperature (Tm) of 87.6,°C and crystalline temperature (Tc) of 64,°C, by the copolymerization of 12HD with 12HS, both the Tm and Tc of the copolymer decreased with increasing 12HS contents, and poly(12HD- co -12HS) containing more than 60 mol-% 12HS was a viscous liquid at room temperature. At the same time, the Young's modulus and hardness also decreased with increasing 12HS content, and poly(12HD- co -36 mol-% 12HS) exhibited an elastic behavior, having a hardness of 70 A using a durometer A. In addition, it showed an excellent biodegradability by activated sludge and chemical recyclability by lipase. [source] Thermal Sensitivity of tert -Butyloxycarbonylmethyl-Modified Polyquats in Condensed Phase and Solubility Properties of Copolymers with N -IsopropylacrylamideMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2010Nina Gonsior Abstract The synthesis of the easily decomposable ionic monomer 2- tert -butoxy- N -[2-(methacryloyl-oxy)ethyl]- N,N -dimethyl-2-oxoethanammonium chloride (3) via thermally induced syn-elimination of a tert -butyl ester group was realized simply by mixing N,N -dimethylaminoethyl methacrylate (1) and tert -butyl chloroacetate (2) at ambient temperature without solvent. The obtained salt was polymerized via free radical polymerization. The decomposition and foaming via iso -butene formation takes place by heating up to about 160,°C. IR, DSC, TGA, and GC/MS measurements were performed to follow this pyrolysis reaction. Furthermore, the copolymerization of 3 with N -isopropylacrylamid (NiPAAm, 5) was carried out with different monomer ratios. Molar mass distributions were measured using an asymmetrical flow field-flow fractionation (aFFFF) system. The obtained copolymers 6,10 exhibit lower critical solution temperature (LCST) behaviour in water with cloud points at different temperatures depending on the monomer ratio. [source] Characterization of New Amphiphilic Block Copolymers of N -Vinyl Pyrrolidone and Vinyl Acetate, 1 , Analysis of Copolymer Composition, End Groups, Molar Masses and Molar Mass Distributions,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2010Nick Fandrich Abstract New amphiphilic block copolymers consisting of N -vinyl pyrrolidone and vinyl acetate were synthesized via controlled radical polymerization using a reversible addition/fragmentation chain transfer (RAFT)/macromolecular design via the interchange of xanthates (MADIX) system. The synthesis was carried out in 1,4-dioxane as process solvent. In order to get conclusions on the mechanism of the polymerization the molecular structure of formed copolymers was analysed by means of different analytical techniques. 13C NMR spectroscopy was used for the determination of the monomer ratios. End groups were analysed by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This technique was also used to determine possible fragmentations of the RAFT end groups. By means of a combination of size exclusion chromatography, 13C NMR and static light scattering molar mass distributions and absolute molar masses could be analysed. The results clearly show a non-ideal RAFT mechanism. [source] Synthesis and Characterization of N -Propargyl Cinnamamide Polymers and CopolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2007Jianping Deng Abstract This paper deals with synthesis and characterization of a novel poly(N -propargylamide) containing cinnamamide groups (poly(1)) in its side chains. Monomer 1, CHCCH2NHCOCHCH(C6H5), was synthesized and polymerized with a rhodium catalyst, (nbd)Rh+B,(C6H5)4 (nbd,=,2,5-norbornadiene). Effects of some factors on polymerization of monomer 1 such as solvent, temperature, and the ratio of monomer/catalyst were investigated in detail; polymers with moderate number-average molecular weights () and low index of polydispersity () were obtained. To improve the polymers' solubility and to elucidate whether poly(1) could form helical conformation, another N -propargylamide monomer 2, CHCCH2NHCOCH(CH2CH3)2, was employed to accomplish copolymerization with monomer 1. Copolymerization with monomer 2 improved obviously the solubility of the (co)polymers; the copolymers with certain monomer ratios could form helices under the examined conditions according to the related UV-vis spectra. [source] Interpenetrating Polymer Networks of Hydrocarbon and Fluorocarbon Polymers: Epoxy/Fluorinated Acrylic MacromonomersMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2010Marco Sangermano Abstract A fluorinated acrylic resin was synthesized for use as a co-monomer with a commercially available epoxy resin for UV-cured interpenetrating polymer network preparation. Hybrid IPN networks were achieved with morphology ranging from a co-continuous IPN to complete phase separation simply by changing monomer ratios. Highly hydrophobic coatings with good adhesion properties on glass substrates were obtained. [source] Mechanistic limitations in the synthesis of polyesters by lipase-catalyzed ring-opening polymerizationBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003Anna A. Panova Abstract Lipase-catalyzed polymerization of caprolactone (CL) in toluene with methoxy-poly(ethylene glycol) (MPEG) and water as initiators was characterized in detail for mechanistic insight. 1H NMR analysis of polycaprolactone chains (PCL), dicaprolactone, degree of esterification of MPEG, and fractions of PCL chains initiated by MPEG and water were used to follow the reactions. The data were analyzed with the kinetic scheme involving formation of the acylenzyme and its consequent reaction with MPEG, water, or PCL to yield the MPEG- or water-initiated PCL chains, or increase in PCL length. A limit for MPEG initiator esterification in lipase-catalyzed CL polymerization was observed and was explained by preferential reaction of PCL propagation over MPEG esterification at long reaction times and low MPEG concentrations. Slower monomer conversion in concentrated monomer solutions was explained by decreased partitioning of PCL between the solvent and the enzyme. This effect resulted in inhibition of the lipase by the reaction product, PCL chains, and/or insufficient diffusion of monomer to the enzyme active site. High monomer/initiators ratio in these solutions did not yield longer polymer chains due to decreased monomer conversion and the corresponding decrease in product yields; lower yields were also observed for chain initiation by MPEG and water. A shift in the reaction rate-limiting step from formation of acylenzyme in dilute CL solutions to its deacylation in concentrated CL solutions yielded higher PCL polydispersity due to increased initiation by water. Enhanced intramolecular cyclization was also observed. Endgroup composition of PCL chains was influenced by the concentration of monomer, ratio of initiators (MPEG and water), and reaction time, yielding PCL chains initiated exclusively by MPEG at "infinite reaction times." © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 103,113, 2003. [source] Preparation of monodisperse nanoparticles containing poly(propylene imine)(NH2)32 -polystyreneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2009Hu Liu Abstract Polypropylenimine dendrimer (DAB-Am-32, generation 4.0) was converted into a macroinitiator DAB-Am-32-Cl via reaction with 2-chloropropionyl chloride. Monodisperse nanoparticles containing poly(propylene imine)(NH2)32 -polystyrene were prepared by emulsion atom transfer radical polymerization (ATRP) of styrene (St), using the DAB-Am-32-Cl/CuCl/bpy as initiating system. The structure of macroinitiator was characterized by FTIR spectrum, 1H NMR, and 13C NMR. The structure of poly(propylene imine)(NH2)32 -polystyrene was characterized by FT-IR spectrum and 1H NMR; the molecular weight and molecular weight distribution of poly(propylene imine)(NH2)32 -polystyrene were characterized by gel permeation chromatograph (GPC). The morphology, size and size distribution of the nanoparticles were characterized by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effects of monomer/macroinitiator ratio and surfactant concentration on the size and size distribution of the nanoparticles were investigated. It was found that the diameters of the nanoparticles were smaller than 100 nm (30,80 nm) and monodisperse; moreover, the particle size could be controlled by monomer/macroinitiator ratios and surfactant concentration. With the increasing of the ratio of St/DAB-Am-32-Cl, the number-average diameter (Dn), weight-average diameter (Dw) were both increased gradually. With enhancing the surfactant concentration, the measured Dh of the nanoparticles decreased, while the polydispersity increased. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2892,2904, 2009 [source] Synthesis and characterization of pH sensitive poly(glycidol)- b -poly(4-vinylpyridine) block copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2009Sebastian Mendrek Abstract Block copolymers of poly(glycidol)- b -poly(4 -vinylpyridine) were obtained by ATRP of 4-vinylpyridine initiated by ,-(2-chloropropionyl) poly(glycidol) macroinitiators. By changing the monomer/macroinitiator ratio in the synthesis polymers with varied P4VP/PGl molar ratio were obtained. The obtained block copolymers showed pH sensitive solubility. It was found that the linkage of a hydrophilic poly(glycidol) block to a P4VP influenced the pKa value of P4VP. DLS measurements showed the formation of fully collapsed aggregates exceeding pH 4.7. Above this pH values the collapsed P4VP core of the aggregates was stabilized by a surrounding hydrophilic poly(glycidol) corona. The size of the aggregates depended significantly upon the composition of the block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1782,1794, 2009 [source] Preparation of monodisperse nanoparticles containing poly(propylene imine)(NH2)32 -polystyreneJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2009Hu Liu Abstract Polypropylenimine dendrimer (DAB-Am-32, generation 4.0) was converted into a macroinitiator DAB-Am-32-Cl via reaction with 2-chloropropionyl chloride. Monodisperse nanoparticles containing poly(propylene imine)(NH2)32 -polystyrene were prepared by emulsion atom transfer radical polymerization (ATRP) of styrene (St), using the DAB-Am-32-Cl/CuCl/bpy as initiating system. The structure of macroinitiator was characterized by FTIR spectrum, 1H NMR, and 13C NMR. The structure of poly(propylene imine)(NH2)32 -polystyrene was characterized by FT-IR spectrum and 1H NMR; the molecular weight and molecular weight distribution of poly(propylene imine)(NH2)32 -polystyrene were characterized by gel permeation chromatograph (GPC). The morphology, size and size distribution of the nanoparticles were characterized by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effects of monomer/macroinitiator ratio and surfactant concentration on the size and size distribution of the nanoparticles were investigated. It was found that the diameters of the nanoparticles were smaller than 100 nm (30,80 nm) and monodisperse; moreover, the particle size could be controlled by monomer/macroinitiator ratios and surfactant concentration. With the increasing of the ratio of St/DAB-Am-32-Cl, the number-average diameter (Dn), weight-average diameter (Dw) were both increased gradually. With enhancing the surfactant concentration, the measured Dh of the nanoparticles decreased, while the polydispersity increased. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2892,2904, 2009 [source] Nonaqueous dispersion polymerization of styrene in methanol with the ionomer block copolymer poly[(4-methylstyrene)- co -(4-vinyltriethylbenzyl ammonium bromide)]- b -polyisobutene as a stabilizerJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2004Yuhong Ma Abstract The nonaqueous dispersion polymerization of styrene in methanol with poly[(4-methylstyrene)- co -(4-vinyltriethylbenzyl ammonium bromide)]- b -polyisobutene as a stabilizer was investigated. There was no observable inducing period or autoacceleration in the polymerization process. The conversion increased almost linearly with the polymerization time as high as 80%. The average sizes of the obtained polystyrene particles increased, and the size distributions of the polystyrene particles tended to become narrower, with increasing conversion. The mechanism of the dispersion polymerization in the presence of polyisobutene- b -poly[(4-methylstyrene)- co -(4-vinyltriethylbenzyl ammonium bromide)] was nucleation/growth. When the stabilizer/monomer ratio (w/w) was greater than 2.0%, the polystyrene dispersion was stable, and there was no observable polymer particle coagulation taking place during the whole polymerization process. The average diameter of the polymer particles can be mediated through changes in the polymerization conversion, monomer, and stabilizer. Nearly monodispersed polystyrene particles with average diameters of approximately 0.45,2.21 ,m were obtained under optimal conditions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2678,2685, 2004 [source] |