Home About us Contact
|
Home About us Contact | ||
|
|
||
Ethyl Methacrylate (ethyl + methacrylate)
Selected AbstractsFunctionalization of Chitosan via Atom Transfer Radical Polymerization for Gene DeliveryADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Yuan Ping Abstract It is of crucial importance to modify chitosan-based polysaccharides in the designing of biomedical materials. In this work, atom transfer radical polymerization (ATRP) was employed to functionalize chitosan in a well-controlled manner. A series of new degradable cationic polymers (termed as PDCS) composed of biocompatible chitosan backbones and poly((2-dimethyl amino)ethyl methacrylate) (P(DMAEMA)) side chains of different length were designed as highly efficient gene vectors via ATRP. These vectors, termed as PDCS, exhibited good ability to condense plasmid DNA (pDNA) into nanoparticles with positive charge at nitrogen/phosphorus (N/P) ratios of 4 or higher. All PDCS vectors could well protect the condensed DNA from enzymatic degradation by DNase I and they displayed high level of transfectivity in both COS7, HEK293 and HepG2 cell lines. Most importantly, in comparison with high-molecular-weight P(DMAEMA) and ,gold-standard' PEI (25 kDa), the PDCS vectors showed considerable buffering capacity in the pH range of 7.4 to 5, and were capable of mediating much more efficient gene transfection at low N/P ratios. At their own optimal N/P ratios for trasnsfection, the PDCS/pDNA complexes showed much lower cytotoxicity. All the PDCS vectors were readily to be degradable in the presence of lysozyme at physiological conditions in vitro. These well-defined PDCS polymers have great potentials as efficient gene vectors in future gene therapy. [source] Colloidal Films That Mimic CiliaADVANCED FUNCTIONAL MATERIALS, Issue 18 2010Fang Liu Abstract Cilia are wavy hair-like structures that extend outward from surfaces of various organisms. They are classified into two general categories, primary cilia, which exhibit sensing attributes, and motile cilia, which exert mechanical forces. A new poly(2-(N,N -dimethylamino)ethyl methacrylate- co -n-butyl acrylate- co - N,N -(dimethylamino) azobenzene acrylamide) (p(DMAEMA/nBA/DMAAZOAm) copolymer is prepared using colloidal synthesis, which, upon coalescence, form films capable of generating surfaces with cilia-like features. While film morphological features allow the formation of wavy whiskers, the chemical composition of the copolymer facilitates chemical, thermal, and electromagnetic responses manifested by simultaneous shape and color changes as well as excitation wavelength dependent fluorescence. These studies demonstrate that synthetically produced polymeric films can exhibit combined thermal, chemical, and electromagnetic sensing leading to locomotive and color responses, which may find numerous applications in sensing devices, intelligent actuators, defensive mechanisms, and others. [source] pH-Responsive Nanoporous Silica Colloidal MembranesADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Olga Schepelina Abstract Free-standing colloidal membranes (nanofrits) with varied thickness and nanopore size are fabricated and modified with pH-responsive poly(2-(dimethylamino)ethyl methacrylate) brushes. The polymer-modified nanofrits demonstrate excellent gating behavior for molecular diffusion: in the presence of acid, the diffusion rate of positively charged species significantly decreases. Increasing the polymer length and membrane thickness and decreasing the nanopore size leads to the complete acid-controlled gating of the membranes. [source] Poly(2-(dimethylamino)ethyl methacrylate) Brushes with Incorporated Nanoparticles as a SERS Active Sensing LayerADVANCED FUNCTIONAL MATERIALS, Issue 11 2010Smrati Gupta Abstract A simple, fast, and versatile approach to the fabrication of outstanding surface enhanced Raman spectroscopy (SERS) substrates by exploiting the optical properties of the Ag nanoparticles and functional as well as organizational characteristics of the polymer brushes is reported. First, poly(2-(dimethylamino)ethyl methacrylate) brushes are synthesized directly on glassy carbon by self-initiated photografting and photopolymerization and thoroughly characterized in terms of their thickness, wettability, morphology, and chemical structure by means of ellipsometry, contact angle, AFM, and XPS, respectively. Second, Ag nanoparticles are homogeneously immobilized into the brush layer, resulting in a sensor platform for the detection of organic molecules by SERS. The surface enhancement factor (SEF) as determined by the detection of Rhodamine 6G is calculated as 6,×,106. [source] An investigation into the morphology and electro-optical properties of 2-hydroxy ethyl methacrylate polymer dispersed liquid crystalsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Huey-Ling Chang Abstract Polymer dispersed liquid crystal (PDLC) films are fabricated using E7 liquid crystals, tetraethylene glycol diacrylate (TeGDA) crosslinking agent, and 0,66.49 mol % 2-hydroxy ethyl methacrylate (HEMA). The effects of different levels of HEMA addition on the microstructure and electro-optical properties of the PDLC samples are examined using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and UV-Vis spectroscopy, respectively. The results show that the refractive index of the PDLC films is insensitive to the level of HEMA addition. However, an increasing HEMA content improves the degree of phase separation during the polymerization process and increases the size and uniformity of the liquid crystal domain. As a result, the electro-optical properties of the PDLC films are significantly improved as the level of HEMA addition is increased. Overall, the results show that a PDLC comprising 40 wt % E7 liquid crystals, 33.51 mol % TeGDA and 66.49 mol % HEMA has a high contrast ratio (13 : 1) and a low driving voltage (10 V) and is therefore an ideal candidate for a wide variety of intelligent photoelectric applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Polypropylene/clay nanocomposites prepared by in situ grafting-melt intercalation with a novel cointercalating monomerJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Pingan Song Abstract Polypropylene (PP)/clay nanocomposites were prepared by melt-compounding PP with organomontmorillonite (OMT), using maleic anhydride grafted polypropylene (PP- g -MA) as the primary compatibilizer and N -imidazol- O -(bicyclo pentaerythritol phosphate)- O -(ethyl methacrylate) phosphate (PEBI) as the cointercalating monomer. X-ray diffraction patterns indicated that the larger interlayer spacing of OMT in PP was obtained due to the cointercalation monomer having a large steric volume and the d -spacing further increased with the addition of PP- g -MA, as evidenced by transmission electron microscopy. Thermogravimetric analysis revealed that the PEBI-containing PP nanocomposites exhibited better thermal stability than PEBI-free PP composites. Dynamic mechanical analysis demonstrated that the storage modulus was significantly enhanced, and the glass transition temperature (Tg) shifted slightly to low temperature with the incorporation of clay for PP/OMT hybrids. PEBI-containing PP/OMT composites gave a lower Tg value because of the strong internal plasticization effect of PEBI in the system. Cone calorimetry showed that the flame-retardancy properties of PP nanocomposites were highly improved with the incorporation of PEBI. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Effect of grafting methacrylate monomers onto jute constituents with a potassium persulfate initiator catalyzed by Fe(II)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Md. Ibrahim H. Mondal Abstract The graft copolymerization of methyl methacrylate and ethyl methacrylate monomers onto jute fiber was carried out in an aqueous medium with potassium persulfate as an initiator under the catalytic influence of ferrous sulfate in the presence of air. The effects of parameter variables, such as the monomer, initiator, and catalyst concentrations, the reaction time, and the temperature, on grafting and the effect of grafting the monomers onto jute constituents were studied. The degree of grafting depended on the kinds of monomers and the parameter variables. The maximum graft yield percentages with methyl methacrylate and ethyl methacrylate under optimized conditions were 18.9 and 38.8%, respectively, and the grafting onto jute fiber was largely affected by one of its main constituents, such as hemicellulose. The graft copolymers were characterized, and their improved properties were also examined. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2369,2375, 2007 [source] Multifunctioning pH-responsive nanoparticles from hierarchical self-assembly of polymer brush for cancer drug deliveryAICHE JOURNAL, Issue 11 2008Youqing Shen Abstract Polymer nanoparticles are extensively explored as drug carriers but they generally have issues of premature burst drug release, slow cellular uptake, and retention in acidic intracellular compartments. Herein, we report multifunctioning three-layered nanoparticles (3LNPs) that can overcome these problems. The 3LNPs have a poly(,-caprolactone) (PCL) core, a pH-responsive poly[2-(N,N-diethylamino)ethyl methacrylate](PDEA) middle layer and a polyethylene glycol (PEG) outer layer. The pH-responsive PDEA layer is insoluble at pH above 7 but becomes positively charged and soluble via protonation at pH lower than 6.5. Thus, this layer has three functions: it covers on the PCL core inhibiting the premature burst drug release at the physiological pH, becomes positively charged and thus promotes endocytosis for fast cellular internalization in the acidic interstitium of solid tumors, and is highly positively charged in lysosomes to disrupt the lysosomal membrane and release the nanoparticle into the cytosol. The multifunctioning nanoparticles are an efficient carrier for cancer cytosolic drug delivery. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source] Titanium-mediated [CpTiCl2(OEt)] ring-opening polymerization of lactides: A novel route to well-defined polylactide-based complex macromolecular architecturesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2010Nikolaos Petzetakis Abstract Among three cyclopentadienyl titanium complexes studied, CpTiCl2(OEt), containing a 5% excess CpTiCl3, has proven to be a very efficient catalyst for the ring-opening polymerization (ROP) of L -lactide (LLA) in toluene at 130 °C. Kinetic studies revealed that the polymerization yield (up to 100%) and the molecular weight increase linearly with time, leading to well-defined PLLA with narrow molecular weight distributions (Mw/Mn , 1.1). Based on the above results, PS- b -PLLA, PI- b -PLLA, PEO- b -PLLA block copolymers, and a PS- b -PI- b -PLLA triblock terpolymer were synthesized. The synthetic strategy involved: (a) the preparation of OH-end-functionalized homopolymers or diblock copolymers by anionic polymerization, (b) the reaction of the OH-functionalized polymers with CpTiCl3 to give the corresponding Ti-macrocatalyst, and (c) the ROP of LLA to afford the final block copolymers. PMMA- g -PLLA [PMMA: poly(methyl methacrylate)] was also synthesized by: (a) the reaction of CpTiCl3 with 2-hydroxy ethyl methacrylate, HEMA, to give the Ti-HEMA-catalyst, (b) the ROP of LLA to afford a PLLA methacrylic-macromonomer, and (c) the copolymerization (conventional and ATRP) of the macromonomer with MMA to afford the final graft copolymer. Intermediate and final products were characterized by NMR spectroscopy and size exclusion chromatography, equipped with refractive index and two-angle laser light scattering detectors. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1092,1103, 2010 [source] Macromolecular brushes synthesized by "grafting from" approach based on "click chemistry" and RAFT polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2010Dongxia Wu Abstract Well-defined macromolecular brushes with poly(N -isopropyl acrylamide) (PNIPAM) side chains on random copolymer backbones were synthesized by "grafting from" approach based on click chemistry and reversible addition-fragmentation chain transfer (RAFT) polymerization. To prepare macromolecular brushes, two linear random copolymers of 2-(trimethylsilyloxy)ethyl methacrylate (HEMA-TMS) and methyl methacrylate (MMA) (poly(MMA- co -HEMA-TMS)) were synthesized by atom transfer radical polymerization and were subsequently derivated to azide-containing polymers. Novel alkyne-terminated RAFT chain transfer agent (CTA) was grafted to polymer backbones by copper-catalyzed 1,3-dipolar cycloaddition (azide-alkyne click chemistry), and macro-RAFT CTAs were obtained. PNIPAM side chains were prepared by RAFT polymerization. The macromolecular brushes have well-defined structures, controlled molecular weights, and molecular weight distributions (Mw/Mn , 1.23). The RAFT polymerization of NIPAM exhibited pseudo-first-order kinetics and a linear molecular weight dependence on monomer conversion, and no detectable termination was observed in the polymerization. The macromolecular brushes can self-assemble into micelles in aqueous solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 443,453, 2010 [source] Synthesis of stimuli-responsive macroazoinitiators and their use as an inistab toward hairy polymer latex particlesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2009Syuji Fujii Abstract Stimuli-responsive macroazoinitiators with central azo unit have been synthesized by atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate or 2-(diethylamino)ethyl methacrylate in 2-propanol at 25 °C. The mean degree of polymerization of the polymer chains besides the azo group was fixed between 25 and 60. 1H NMR, gel permeation chromatography, UV-Vis spectrophotometer, and surface tensiometer were used to characterize the stimuli-responsive macroazoinitiators in terms of their chemical structure, molecular weight, polydispersity, and pH-responsive behavior, respectively. Eventually, dispersion polymerization of styrene using the poly[2-(diethylamino)ethyl methacrylate] (PDEA) macroazoinitiator as an inistab (initiator + stabilizer) in 2-propanol medium was conducted. Near-monodisperse 98 nm polystyrene (PS) latex particles with pH-responsive PDEA hair were successfully synthesized. The PS latex particles with the PDEA hair can be dispersed in acidic aqueous media where the PDEA hair was protonated and was solvated, and can be flocculated in basic aqueous media where the PDEA hair was deprotonated and was precipitated. This dispersion-flocculation cycle was reversible. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3431,3443, 2009 [source] One-pot synthesis of ABC miktoarm star terpolymers by coupling ATRP, ROP, and click chemistry techniquesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 12 2009Yanfeng Zhang Abstract We report on the one-pot synthesis of well-defined ABC miktoarm star terpolymers consisting of poly(2-(dimethylamino)ethyl methacrylate), poly(,-caprolactone), and polystyrene or poly(ethylene oxide) arms, PS(- b -PCL)- b -PDMA and PEO (- b -PCL)- b -PDMA, taking advantage of the compatibility and mutual tolerability of reaction conditions (catalysts and monomers) employed for atom transfer radical polymerization (ATRP), ring-opening polymerization (ROP), and click reactions. At first, a novel trifunctional core molecule bearing alkynyl, hydroxyl group, and bromine moieties, alkynyl(OH)Br, was synthesized via the esterification reaction of 5-ethyl-5-hydroxymethyl-2,2-dimethyl-1,3-dioxane with 4-oxo-4-(prop-2-ynyloxy)butanoic acid, followed by deprotection and monoesterification of alkynyl(OH)2 with 2-bromoisobutyryl bromide. In the presence of trifunctional core molecule, alkynyl(OH)Br, and CuBr/PMDETA/Sn(Oct)2 catalytic mixtures, target ABC miktoarm star terpolymers, PS(- b -PCL)- b -PDMA and PEO(- b -PCL)- b -PDMA, were successfully synthesized in a one-pot manner by simultaneously conducting the ATRP of 2-(dimethylamino)ethyl methacrylate (DMA), ROP of ,-caprolactone (,-CL), and the click reaction with azido-terminated PS (PS- N3) or azido-terminated PEO (PEO- N3). Considering the excellent tolerability of ATRP to a variety of monomers and the fast expansion of click chemistry in the design and synthesis of polymeric and biorelated materials, it is quite anticipated that the one-pot concept can be applied to the preparation of well-defined polymeric materials with more complex chain architectures. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3066,3077, 2009 [source] Synthesis of azobenzene-containing polymers via RAFT polymerization and investigation on intense fluorescence from aggregates of azobenzene-containing amphiphilic diblock copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2008Jie Xu Abstract The well-defined azobenzene-containing homopolymers, poly{6-(4-phenylazophenoxy)hexyl methacrylate (AHMA)} (PAHMA), were synthesized via reversible addition fragmentation chain transfer polymerization (RAFT) in anisole solution using 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the RAFT agent and 2,2,-azobisisobutyronitrile (AIBN) as the initiator. The first-order kinetic plot of the polymerization and the linear dependence of molecular weights of the homopolymers with the relatively low polydispersity index values (PDIs , 1.25) on the monomer conversions were observed. Furthermore, the amphiphilic diblock copolymer, poly{6-(4-phenylazophenoxy)hexyl methacrylate (AHMA)}- b -poly{2-(dimethylamino)ethyl methacrylate (DMAEMA)} (PAHMA- b -PDMAEMA), was prepared with the obtained PAHMA as the macro-RAFT agent. The structures and properties of the polymers were characterized by 1H NMR and GPC, respectively. Interestingly, the amphiphilic diblock copolymers in chloroform (CHCl3) solution (PAHMA23 - b -PDMAEMA97 (4 × 10,5 M, Mn(GPC) = 18,400 g/mol, PDI = 1.48) and PAHMA28 - b -PDMAEMA117 (6 × 10,5 M, Mn(GPC) = 19,300 g/mol, PDI = 1.51) exhibited the intense fluorescence emission at ambient temperature. Moreover, the fluorescent intensity of PAHMA- b -PDMAEMA in CHCl3 was sensitive to the ultraviolet irradiation at 365 nm, which increased within the first 10 min and later decreased when irradiation time was prolonged to 30 min or longer. The well distributed, self-assembled micelles composed of azobenzene-containing amphiphilic diblock copolymers, (PAHMA- b -QPDMAEMA)s (QPDMAEMA is quaternized PDMAEMA), in the mixed N,N -dimethyl formamide (DMF)/H2O solutions were prepared. Their fluorescent intensities decreased with the increasing amount of water. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5652,5662, 2008 [source] Synthesis and supramolecular self-assembly of thermosensitive amphiphilic star copolymers based on a hyperbranched polyether coreJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2008Haiyan Hong Abstract A novel amphiphilic thermosensitive star copolymer with a hydrophobic hyperbranched poly (3-ethyl-3-(hydroxymethyl)oxetane) (HBPO) core and many hydrophilic poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) arms was synthesized and used as the precursor for the aqueous solution self-assembly. All the copolymers directly aggregated into core,shell unimolecular micelles (around 10 nm) and size-controllable large multimolecular micelles (around 100 nm) in water at room temperature, according to pyrene probe fluorescence spectrometry and 1H NMR, TEM, and DLS measurements. The star copolymers also underwent sharp, thermosensitive phase transitions at a lower critical solution temperature (LCST), which were proved to be originated from the secondary aggregation of the large micelles driven by increasing hydrophobic interaction due to the dehydration of PDMAEMA shells on heating. A quantitative variable temperature NMR analysis method was designed by using potassium hydrogen phthalate as an external standard and displayed great potential to evaluate the LCST transition at the molecular level. The drug loading and temperature-dependent release properties of HBPO- star -PDMAEMA micelles were also investigated by using indomethacin as a model drug. The indomethacin-loaded micelles displayed a rapid drug release at a temperature around LCST. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 668,681, 2008 [source] Synthesis of PS and PDMAEMA mixed polymer brushes on the surface of layered silicate and their application in pickering suspension polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2007Yongfang Yang Abstract An ammonium free radical initiator was ion exchanged onto the surface of clay layers. Polystyrene (PS) and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) mixed polymer brushes on the surface of clay layers were prepared by in situ free radical polymerization. PS colloid particles armored by clay layers with mixed polymer brushes were prepared by Pickering suspension polymerization. Transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to characterize the structure and morphology of the colloid particles. Clay layers on the surface of PS colloid particles can be observed. Because of the cationic nature of the PDMAEMA brushes the colloid particles have positive zeta potentials at low pH values. X-ray photoelectron spectroscopy (XPS) was used to analyze the surface of the colloid particles. N1s binding energy of PDMAEMA chains on the surface of clay layers was detected by XPS. The two peaks of the N1s binding energy indicate two different nitrogen environments on the surface of clay layers. The peak with a lower binding energy is characteristic of neutral nitrogen on PDMAEMA chains, and the peak with a higher binding energy is attributed to protonated nitrogen on PDMAEMA chains. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5759,5769, 2007 [source] Synthesis of well-defined glycidyl methacrylate based block copolymers with self-activation and self-initiation behaviors via ambient temperature atom transfer radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2007Ping Jiang Abstract Well-defined glycidyl methacrylate (GMA) based di- and triblock copolymers, with self-activation and self-initiation behaviors by incorporation of 2-(diethylamino) ethyl methacrylate (DEA) blocks, were synthesized via ambient temperature atom transfer radical polymerization (ATRP). The stability of the GMA pendant oxirane rings in tertiary amine environments at ambient temperature was investigated. More importantly, both self-activation behavior in oxirane ring opening addition reaction and self-initiation behavior in post-cure oxirane ring opening crosslinking of these block copolymers were evidenced by 1H NMR studies. The results demonstrated that the reactivity of pendent oxirane rings was strongly dependant on the nucleophilicity and steric hindrance of tertiary amine moieties and temperature. This facilitated the synthesis of well-defined block copolymers of GMA and DEA via sequential monomer addition ATRP, particularly for polymerization of GMA monomer at ambient temperature. Moreover, these one-component GMA based block polymers have novel self-activation and self-initiation properties, rendering some potential applications in both enzyme immobilization and GMA-based thermosetting materials. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2947,2958, 2007 [source] Frontal polymerization with monofunctional and difunctional ionic liquid monomersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2007Zulma Jiménez Abstract For the first time, we studied frontal polymerization with ionic liquid monomers. We synthesized a series of compounds from the neutralization reaction between trialkylamines (tributylamine, trihexylamine, trioctylamine, and (2-dimethylamino)ethyl methacrylate) and acrylic or methacrylic acid. For the ionic liquids prepared from the unreactive amines, frontal polymerization could not be achieved without the addition of a diacrylate. With the addition of a diacrylate, the front velocities were slower than for dodecyl acrylate (with the diacrylate), a compound of comparable molecular weight. Monomers prepared from the (2-dimethylamino)ethyl methacrylate could support frontal polymerization alone but the front velocities were lower than dodecyl (meth)acrylate. These results are contrasted with recent results of Jiménez et al. for room temperature kinetics. Finally, the polymers prepared were comparable to those prepared by batch curing at 75 °C except for the monomethacrylate ionic liquid, which lost some tertiary amine by dissociation and evaporation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2745,2754, 2007 [source] Amphiphilic star-block copolymers based on a hyperbranched core: Synthesis and supramolecular self-assemblyJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2005Zhifeng Jia Abstract Novel amphiphilic star-block copolymers, star poly(caprolactone)- block -poly[(2-dimethylamino)ethyl methacrylate] and poly(caprolactone)- block -poly(methacrylic acid), with hyperbranched poly(2-hydroxyethyl methacrylate) (PHEMA,OH) as a core moiety were synthesized and characterized. The star-block copolymers were prepared by a combination of ring-opening polymerization and atom transfer radical polymerization (ATRP). First, hyperbranched PHEMA,OH with 18 hydroxyl end groups on average was used as an initiator for the ring-opening polymerization of ,-caprolactone to produce PHEMA,PCL star homopolymers [PHEMA = poly(2-hydroxyethyl methacrylate); PCL = poly(caprolactone)]. Next, the hydroxyl end groups of PHEMA,PCL were converted to 2-bromoesters, and this gave rise to macroinitiator PHEMA,PCL,Br for ATRP. Then, 2-dimethylaminoethyl methacrylate or tert -butyl methacrylate was polymerized from the macroinitiators, and this afforded the star-block copolymers PHEMA,PCL,PDMA [PDMA = poly(2-dimethylaminoethyl methacrylate)] and PHEMA,PCL,PtBMA [PtBMA = poly(tert -butyl methacrylate)]. Characterization by gel permeation chromatography and nuclear magnetic resonance confirmed the expected molecular structure. The hydrolysis of tert -butyl ester groups of the poly(tert -butyl methacrylate) blocks gave the star-block copolymer PHEMA,PCL,PMAA [PMAA = poly(methacrylic acid)]. These amphiphilic star-block copolymers could self-assemble into spherical micelles, as characterized by dynamic light scattering and transmission electron microscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6534,6544, 2005 [source] Influence of the cocatalyst structure on the statistical copolymerization of methyl methacrylate with bulky methacrylates using the zirconocene complex Cp2ZrMe2JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2005Konstantinos Kostakis Abstract Statistical copolymers of methyl methacrylate with cyclohexyl and trimethylsilyloxy ethyl methacrylate were synthesized with two different catalytic systems based on the zirconocene complex Cp2ZrMe2. The reactivity ratios of methyl methacrylate and these methacrylates were calculated with the Finemann,Ross, inverted Finemann,Ross, and Kelen,Tüdos graphical methods. The structural parameters of these copolymers were estimated from the calculation of the dyad monomer sequence fractions. Two different borate cocatalysts were employed, and their effect on the copolymerization process is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3305,3314, 2005 [source] Controlled polymerizations of 2-(dialkylamino)ethyl methacrylates and their block copolymers in protic solvents at ambient temperature via ATRPJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2004Baowei Mao Abstract Very well-controlled polymerizations of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and 2-(diethylamino)ethyl methacrylate (DEAEMA) in aqueous and methanolic solutions via atom transfer radical polymerization (ATRP) at ambient temperature were demonstrated. Poly(DMAEMA) and poly(DEAEMA) of low polydispersity index (PDI) of ,1.07 were obtained using the p -toluenesulfonyl chloride/CuCl/1,1,4,7,10,10-hexamethyl-triethylenetetramine (p -TsCl/CuCl/HMTETA) system. Excellent control of polymerization was achieved even in pure methanol. This is in contrast with the very poor control of DMAEMA ATRP in methanol reported previously using a different intiator/catalyst/ligand system. The initiator p -TsCl underwent hydrolysis reaction in aqueous methanolic solutions with a second-order rate constant of 6.1 × 10,4 dm3 mol,1 s,1 at 25 °C. Both poly(DMAEMA) and poly(DEAEMA) retained almost full chlorine-functionization at the chain ends. Well-defined block copolymers of DEAEMA and DMAEMA were successfully obtained by starting with either macroinitiators of DEAEMA or DMAEMA. Other well-defined diblock copolymers could be prepared using these macroinitiators. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5161,5169, 2004 [source] Synthesis and characterization of secondary-amine-functional microparticlesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2004E. Banu Altinta Abstract Secondary-amine-functional microparticles were prepared in the range of 50,250 ,m through the suspension polymerization of styrene, divinylbenzene (DVB), and 2-(tert -butylamino)ethyl methacrylate (tBAEMA). This study focused on the effects of the DVB, tBAEMA, initiator, and stabilizer concentrations and shaking rate on the experimental amine content, swelling ratio, average particle size, and particle size distribution. The suspension polymerization experiments were carried out in two different systems. In the first system, an organic phase, including the monomers and initiator, was dispersed in an aqueous medium in the presence of Al2(SO4)3. Al2(SO4)3, in the presence of an amine monomer (pH , 10), formed colloidal Al(OH)3, which built a nonsticky layer on the surface of the polymerizing droplets that prevented them from coalescing and aggregating. Individual and spherical particles within the range of 50,200 ,m were obtained by this polymerization method. The second method was similar to the first polymerization protocol, except that a certain amount of sodium dodecyl sulfate was added as a costabilizer in the presence of Al2(SO4)3. In these experiments, individual and spherical particles were obtained within the range of 130,250 ,m. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem: 3708,3719, 2004 [source] Dispersion polymerization of styrene in carbon dioxide stabilized by copolymers of poly(propylene glycol) methacrylate and 2-(perfluorooctyl)ethyl methacrylateJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2003Lunhan Ding Abstract The dispersion polymerization of styrene in carbon dioxide with a series of copolymers of poly(propylene glycol) methacrylate (PPGMA) and 2-(perfluorooctyl)ethyl methacrylate (FOEMA) as the polymerization dispersants was examined. It was demonstrated that PPGMA and FOEMA copolymers and polymers containing 52,100% FOEMA could be used as effective dispersants for the polymerization, and the composition of the copolymeric dispersant had a dramatic effect on both the polymerization yield and the morphology of the resulting polystyrene. The effects of the concentrations of the copolymeric dispersants, the concentrations of the monomer, and the reaction pressure were also investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3804,3815, 2003 [source] Synthesis of new crosslinkable polymers by chemoselective polymerizations of 2-(1-aziridinyl)ethyl methacrylateJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2003Takashi Ishizone The anionic vinyl polymerization of 2-(1-aziridinyl)ethyl methacrylate (1) quantitatively proceeded with diphenylmethylpotassium in the presence of diethylzinc in tetrahydrofuran at ,78 °C for 12 h to form a polymethacrylate (2) with an aziridine ring in each repeating unit. The resulting polymer 2 possessed the predicted molecular weight and narrow molecular weight distribution (weight-average molecular/number-average molecular weight < 1.1) and became readily insoluble by treatment with adipic acid via the crosslinking of the pendant aziridinyl moiety. A poly(ethylene imine) bearing methacryloyl pendant groups was obtained with triethyloxonium tetrafluoroborate via the cationic ring-opening polymerization of 1 in heptane/dichloromethane at 0 °C for 2 h. [source] Copolymerization of (2-phenyl-1,3-dioxolane-4-yl)methyl methacrylate with alkyl methacrylates: Reactivity ratios and copolymer characterizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2002Mehmet Co Abstract The radical copolymerizations of (2-phenyl-1,3-dioxolane-4-yl-)methyl methacrylate (PDMMA) with methyl methacrylate (MMA), ethyl methacrylate (EMA), and butyl methacrylate (BMA) were studied in dioxane at 60 °C with benzoyl peroxide as an initiator. The glass-transition temperatures of poly(PDMMA- co -MMA), poly(PDMMA- co -EMA), and poly(PDMMA- co -BMA) varied from 130 to 138 °C, from 100 to 134 °C, and from 63 to 122 °C, respectively, depending on the copolymer composition. Along with some physicochemical properties and thermal stability investigations of the copolymers, the monomer reactivity ratios were also determined with the conventional Finemann,Ross and Kelen,Tüdös linearization methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1184,1191, 2002 [source] Molecular imprinting of AMP by an ionic-noncovalent dual approachJOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2009Florent Breton Abstract In order to mimic recognition properties of adenylate kinase, molecularly imprinted polymers (MIPs) were prepared for adenosine 5,-monophosphate (AMP), a substrate of the enzyme. Different functional monomers interacting with the phosphate moiety were tested, and the MIP giving the best specific binding of AMP was composed with one equivalent of 2-(dimethylamino)ethyl methacrylate and ten equivalents of acrylamide compared to AMP. Packed into solid phase cartridge, this polymer showed similar characteristics than the enzyme, since it was specific for AMP toward other nucleotides. [source] Efficient Encapsulation of Plasmid DNA in pH-Sensitive PMPC,PDPA Polymersomes: Study of the Effect of PDPA Block Length on Copolymer,DNA Binding AffinityMACROMOLECULAR BIOSCIENCE, Issue 5 2010Hannah Lomas Abstract We report the self-assembly of a series of amphiphilic diblock copolymers comprising a biocompatible, hydrophilic block, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and a pH-sensitive block, poly(2-(diisopropylamino)ethyl methacrylate) (PDPA), into a dispersion of colloidally stable, nanometer-sized polymersomes at physiological pH and salt concentration. The pH-sensitivity of the PDPA block affords the electrostatic interaction of these block copolymers with nucleic acids at endocytic pH, as a result of the protonation of its tertiary amine groups at pH values below its pKa. Herein we investigate the effect of PDPA block length on the binding affinity of the block copolymer to plasmid DNA. [source] Multi-Responsive Supramolecular Double Hydrophilic Diblock Copolymer Driven by Host-Guest Inclusion Complexation between , -Cyclodextrin and Adamantyl MoietiesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 24 2009Hao Liu Abstract Well-defined , -CD-terminated poly(N -isopropylacrylamide) (, - CD -PNIPAM) was synthesized via a combination of atom transfer radical polymerization (ATRP) and click chemistry. Moreover, adamantyl-terminated poly(2-(diethylamino)ethyl methacrylate) (Ad -PDEA) was synthesized by ATRP using an adamantane-containing initiator. Host-guest inclusion complexation between ,-CD and adamantyl moieties drives the formation of supramolecular double hydrophilic block copolymers (DHBC) from , -CD-PNIPAM and Ad -PDEA. The obtained supramolecular PNIPAM- b -PDEA diblock copolymer exhibits intriguing multi-responsive and reversible micelle-to-vesicle transition behavior in aqueous solution by dually playing with solution pH and temperatures. [source] Multifunctional Polymethacrylates Obtained Via ATRP of Functional and Reactive Monomers Followed by Polymer Analogous Reaction with Functional AminesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19 2008Dragos Popescu Abstract Starting from methyl methacrylate (MMA), butyl methacrylate (BMA), allyl methacrylate (AMA), phenoxycarbonyloxy ethyl methacrylate (PCEMA), and functional amines different multifunctional polymethacrylates are accessible. The reactive monomer PCEMA was synthesized starting from 2-hydroxyethyl methacrylate, and then copolymerized via ATRP with other methacrylates in order to obtain reactive copolymers which were subjected to polymer analogous reactions with different functional amines leading to multifunctional polymethacrylates. These can be used for the preparation of multifunctional surfaces. [source] pH-Switchable Complexation between Double Hydrophilic Heteroarm Star Copolymers and a Cationic Block PolyelectrolyteMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2008Zhishen Ge Abstract Double hydrophilic heteroarm star copolymers of poly(methacrylic acid) (PMAA) and poly(ethylene oxide) (PEO) were synthesized via atom-transfer radical polymerization (ATRP) using the "in-out" method. The synthesis consisted of three steps. Namely, ATRP was applied to the preparation of a star macroinitiator with PEO arms and a cross-linked core resulting from the polymerization of divinylbenzene (DVB) in the first step, chain extension with tert -butyl methacrylate (tBMA) under ATRP conditions, and subsequent hydrolysis of the tert -butyl groups afforded (PEO)n -PDVB-(PMAA)n heteroarm star copolymers with a cross-linked microgel core. This novel type of double hydrophilic heteroarm star copolymer can be considered as unimolecular micelles with hybrid coronas. The star copolymers exhibited pH-dependent solubility in water, being soluble at high pH and insoluble at low pH, due to the formation of hydrogen-bonded complexes between the PEO and PMAA arms. A mixed solution of the heteroarm star copolymer and a PEO- b -PQDMA diblock copolymer, where PQDMA is poly(2-(dimethylamino)ethyl methacrylate) fully quaternized with methyl iodide, remained stable in the whole pH range, and exhibited an intriguing pH-switchable complexation behavior accompanied with structural rearrangement. [source] Double-Grafted Cylindrical Brushes: Synthesis and Characterization of Poly(lauryl methacrylate) BrushesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 15 2007Youyong Xu Abstract Double-grafted cylindrical brushes with poly(lauryl methacrylate) (PLMA) as the side chains were synthesized using the grafting-from strategy via atom transfer radical polymerization (ATRP). The polyinitiator poly[2-(2-bromoisobutyryloxy)ethyl methacrylate] (PBIEM) with ,=,240 and 1,500 served as the backbone. The PLMA side chains of the brushes carry long alkyl chains. GPC and 1H NMR measurements confirmed the successful formation of the PLMA cylindrical brushes. The side chains were cleaved from the cylindrical brushes by transesterification. GPC and 1H NMR results indicate that the initiating efficiency of the bromoester groups on the backbone for the bulky monomer was in the range of 0.34,,,f,,,0.67. Static and dynamic light scattering show that the ratio of the radius of gyration to the hydrodynamic radius, Rg/Rh, is in the range of 1.2,1.3, indicating that the LMA cylindrical brushes are semiflexible in solution. Atomic force microscopy (AFM) measurements show that short PLMA brushes exhibit a spherical morphology while the long brushes exhibit a worm-like structure. DSC displayed melting peaks at around ,30,°C, indicating the alkyl side chains of the PLMA chains in the double-grafted cylindrical brushes are crystallizable. [source] | ||||||||||||||||