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Sequential group transfer polymerization of cross-linker, monomer (methyl methacrylate), and cross-linker again is used to prepare cleavable polymer networks based on interconnected “core-first” star polymers. By employing a degradable and a nondegradable cross-linker, four networks are prepared. While cleavage of the degradable cross-linker residues leads to complete polymer network dissolution, the degradation products do not always display the expected molecular weight features. These products are the expected in the case of the network prepared using only the degradable cross-linker (monomodal size distribution with expected low molecular weight) and also in the case of the network prepared using first the degradable and then the nondegradable cross-linker (bimodal size distribution including high molecular weight star polymers), but not so in the case of the network prepared using first the nondegradable and then the degradable cross-linker, where the expected high molecular weight star polymer component is missing due to star recombination after hydrolysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 219 1

In this study, a series of microencapsulated phase change materials with poly(methyl methacrylate-co-methacrylic acid) P(MMA-co-MAA) shell and n-octadecane or n-eicosane core were synthesized by emulsion polymerization method. The aim was to produce microencapsulated n-alkanes having functional groups on their outer surface, so that functional groups would help increasing physical interactions between microcapsules and fiber surface. Therefore, methyl methacrylate (MMA), ethylene glycoldimethacrylate (EGDM), and methacrylic acid (MAA) were copolymerized in oil phase of n-alkane. FT-IR results proved the successful synthesis of P(MMA-co-MAA) shell of microencapsulated n-alkanes. The DSC results indicated that the microencapsulated n-alkanes have considerable latent heat storage capacity in a range of 58-145J/g. The average melting and freezing temperatures of the microencapsulated n-alkanes were measured as 27 and 26 degrees C for n-octadecane and 36 and 35 degrees C for n-eicosane, respectively. The microcapsules were of spherical and compact shape with particle sizes between 15 and 32m. The microcapsules on the cotton fabric applied by pad-dry-cure method were found highly durable and they showed sufficient stability upon several washings and rub fastness. Thermo-regulating properties of the fabrics were declared as a result of thermal history measurements.

High-molecular-weight (MW) symmetrical multiblock copolymers, based on the hydrophobic monomers styrene (Sty) and methyl methacrylate (MMA), and the more polar monomer, 2-vinyl pyridine (2VPy), were prepared using stepwise reversible addition-fragmentation chain transfer polymerization. All copolymers shared a common poly(ethylene glycol) (PEG) midblock, introduced as a bifunctional macromolecular chain transfer agent. In total, five ABA triblock copolymers, five ABCBA pentablock terpolymers, and two ABCDCBA heptablock quaterpolymers (comprising four different monomer types) were synthesized. The MWs of the multiblock polymers were determined using gel permeation chromatography (GPC) and proton nuclear magnetic resonance (1H NMR) spectroscopy, with the latter values being closer to the theoretically expected, whereas GPC MW distributions were relatively narrow, broadening with the number of blocks. The compositions of the synthesized polymers, as determined by 1H NMR spectroscopy, were also close to the expected values. Finally, films cast from chloroform solutions of the pentablock terpolymers P2VPy-b-PSty-b-PEG-b-PSty-b-P2VPy, PSty-b-PMMA-b-PEG-b-PMMA-b-PSty, and P2VPy-b-PMMA-b-PEG-b-PMMA-b-P2VPy examined using transmission electron microscopy exhibited PSty and PMMA cylinders (first two) and lamellae (third terpolymer). © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4957–4965

Two series of polyampholyte (PA) hydrogels were prepared via reversible addition-fragmentation chain transfer polymerization, followed by removal of the protecting group of the acidic monomer repeating units (methacrylic acid, MAA), which were common in both series. One series bore (pyridin-2-yl)methyl methacrylate (2PyMMA) basic monomer repeating units, whereas the second series carried basic monomer repeating units of 2-(dimethylamino)ethyl methacrylate (DMAEMA). The 2PyMMA-MAA combination in the first series had the peculiarity that the basic 2PyMMA units were more acidic than the MAA units, thus resulting in so-called inverse PA hydrogels. The DMAEMA-MAA pair in the other series led to regular PA hydrogels in which the basicity and acidity of the two types of units were in the conventional sense. The swelling and hydrogen ion equilibrium properties of the two series were explored and thoroughly compared to each other. The aqueous degrees of swelling of inverse PA hydrogels were found to be generally lower than those of the regular ones due to the more hydrophobic character of the 2PyMMA basic units employed in inverse compared to those (DMAEMA) in regular PA gels. The aqueous swelling pH-profiles in both series of PA hydrogels presented a minimum. However, this swelling minimum was deeper and wider in the case of inverse PA hydrogels, because of the greater hydrophobicity of the basic (2PyMMA) units and the greater difference in the effective pK values of the two types of units (2PyMMA-MAA) in inverse PA hydrogels, respectively. This larger separation of the pK in inverse PA gels was directly confirmed from the hydrogen ion titration curves of all the gels. Finally, the isoelectric points of inverse PA hydrogels possessed no detectable dependence on PA composition, which must be contrasted to the strong composition-dependence of the isoelectric points of regular PAs. © 2016 American Chemical Society. 49 10 3869 3880 Cited By :6

A novel bifunctional bis(hemiacetal ester) chain transfer agent (CTA), 1,2-bis[1-(4-cyano-4-methyl-1-oxo-4-(phenylcarbonothioylthio)butanoxy)ethoxy] ethane (CMPTBEE), appropriate for the reversible addition-fragmentation chain transfer (RAFT) polymerization of methacrylate monomers, was successfully synthesized and used for the preparation of a family of 10 hydrolyzable end-linked polymer (co)networks. The family comprised three methyl methacrylate (MMA) homopolymer networks with different degrees of polymerization, 100, 150, and 200, and seven end-linked amphiphilic polymer conetworks of MMA and 2-(dimethylamino)ethyl methacrylate (DMAEMA) with a constant overall degree of polymerization equal to 200 but various compositions and architectures. The agreement of the experimentally measured molecular weights with the theoretically expected ones and the low molecular weight dispersities of the linear precursors to the (co)networks indicated successful control of the polymerization. All (co)networks were characterized in terms of their sol fraction and in terms of their degree of swelling in THF. The value of the former was found in the range between 4 and 50%, whereas that of the latter was around 13%. The presence of the hemiacetal ester groups allowed the hydrolysis of the most hydrophilic, DMAEMA-rich conetworks. The resistance to hydrolysis of the other (co)networks could be attributed to the large hydrophobic blocks surrounding and protecting from hydrolysis the hemiacetal ester groups of the CTA residue in the conetworks. © 2012 American Chemical Society. 45 19 7890 7899 Cited By :22

Dispersion of fullerene, C 60, by addition of polymethacrylate dispersant in methyl methacrylate (MMA) and incorporation of C 60 into poly(methyl methacrylate) (PMMA) were investigated. Copolymers synthesized by radical copolymerization of MMA and 2-naphthyl methacrylate (NMA), poly(MMA-co-NMA), effectively dispersed C 60 in MMA to form clusters of 20 nm. In these cases, addition of minimal 110 naphthyl groups per unit C 60 molecule afforded to give clusters with minimum of 20 nm sizes. Furthermore, block copolymers, poly(MMA-b-NMA) with MMA/NMA mole ratio from 12:1 to 20:1, also efficiently dispersed C 60 to give formation of clusters of 20 nm size by addition of minimal 40 naphthyl groups per unit C 60 molecule, which was corresponding to approximate nine layers of naphthyl group in block copolymer adsorbed on the surface of the cluster. Hybrid films of C 60/PMMA, prepared by casting of C 60-dispersed solution containing PMMA, exhibited absorbance at 400 nm linearly increased with C 60 content., Colloid and Polymer Science, 290(12), pp.1221-1226; 2012

Polypropylene is a widely used commodity plastic from an industrial point of view. Typical applications include both low and high technological content, as it has a good balance between overall properties, processability and cost. However, it is important to remark its intrinsic low surface energy which leads to high chemical inertness. This has an important restriction on some technical applications that require joining and/or finishing processes such as painting. Therefore, the use of polypropylene in these applications requires previous surface modification in order to increase surface activity. Surface modification can be carried out by physical processes such as plasmas or by chemical ways. Surface chemical modification is characterized by relatively low cost and easy implementation at industrial scale. In this work, we have used a chemical process to improve adhesion properties on polypropylene substrates. The selected method has been ultraviolet photografting of methyl methacrylate (MMA) monomer. This process allows increasing surface activity and this has a positive effect on polypropylene-polypropylene adhesion joints. Surface changes have been followed by contact angle measurements and subsequent surface free energy calculation. The evolution of mechanical properties of adhesion joints (T-peel and shear conditions) in terms of the previous exposure time to UV radiation has been evaluated. Optical microscopy (OM) and scanning electron microscopy (SEM) have been used to characterize adhesion fracture type. © 2011 Elsevier Ltd., Authors thank "Ministerio de Ciencia e Innovacion", contract Grant Number: IPT-310000-2010-37 confinanced by FEDER funds (European Union) and Polytechnic University of Valencia PAID 05-10 Ref.: 2489 for financial support. Also, microscopy services at UPV are acknowledged for SEM and AFM support.

Despite polypropylene is one of the most used commodity plastics, its adhesion properties are remarkably restricted by its non-polar nature which leads to low wetting properties and, consequently, poor adhesion behavior. We report the use of ultraviolet photografting process of methyl methacrylate (MMA) monomer as an efficient chemical treatment for surface activation of polypropylene. Contact angle measurements are used for evaluating changes in polypropylene wetting properties together with surface free energy calculations. Chemical changes are showed in terms of the exposure time to UV radiation. Scanning electron microscopy has been used to evaluate topography changes in a qualitative way; atomic force microscopy has been used for a quantitative evaluation of surface changes in terms of roughness. The use of Fourier transformed infrared spectroscopy has revealed the nature of the chemical changes induced by the photografting process of MMA. © 2011 Springer Science+Business Media, LLC., This study is a part of the project IPT-310000-2010-037, "ECOTEXCOMP: Research and development of textile structures useful as reinforcement of composite materials with marked ecological character" funded by the "Ministerio de Ciencia e Innovacion," with an aid of 189540.20 euros, within the "Plan Nacional de Investigacion Cientifica, Desarrollo e Innovacion Tecnologica 2008-2011" and funded by the European Union through FEDER funds, Technology Fund 2007-2013, Operational Programme on R + D + i for and on behalf of the companies." Also, microscopy services at UPV are acknowledged for SEM and AFM support.

Polystyrene, poly(methylacrylate) and poly(methyl methacrylate) four and three-arm stars were synthesized by Reversible Addition Fragmentation chain-Transfer (RAFT) polymerization by using two new dithioester-derived chain transfer agents [CTA or R-S-(C = S)Z]), CTA-1 and CTA-2. CTA-1 is a four arm CTA while CTA-2 is a three-arm CTA. These were easily synthesized from commercially available reagents and were characterized by spectroscopic techniques such as 1H-NMR, 13C-NMR, IR and mass spectrometry. It is demonstrated that the two new CTAs enable the growth of arms away from the core (i.e., core first approach). An attempt has been made to study the effect of the structure of the R-group, which is present as the core in the CTA, on the polymerization, by analyzing the detailed kinetics. This study suggests that CTA-2, with a benzylic R group, enables the controlled star polymerization of styrene while CTA-1, with a R group similar in structure to the propagating radical derived from the polymerization of methyl acrylate (MA), enables the controlled polymerization of MA although to a lesser extent. This study also reveals that the temperature of free radical initiated RAFT (star) polymerization should be chosen in such a way that it is a compromise between reasonable rate of homolysis of the initiator and the CTA (R-group). � Taylor & Francis Group, LLC.

Amphiphilic polymer conetworks were synthesized by the end-linking of ABA triblock copolymers using optimal (minimal) amount of cross-linker in pursuit of nanoscale phase separated materials with a long-range order. Small-angle neutron scattering (SANS) was employed to investigate the structure of the conetworks in D2O. The measurements revealed single SANS correlation peaks, indicating a short-range, liquid-like order within the conetworks, similar to that observed in counterparts prepared using super-optimal amount of cross-linker. This was attributed to the relatively low molecular weight of the chains and the constraints of end-linking. Thus, a reduced loading of cross-linker did not affect the structure of the conetworks. In contrast, the conetwork structure was significantly affected by the polymer architecture at minimal cross-linker loading, with much less intense SANS correlation peaks exhibited by the BAB triblock and the statistical copolymer end-linked conetworks, and the randomly cross-linked statistical conetwork. © 2009 Elsevier Ltd. All rights reserved. 46 3 441 449 Cited By :10

Tiglic acid esters are naturally derived olefins of pleasant odor but incapable of undergoing free-radical polymerization due to the steric hindrances conferred by the β-methyl group. In an effort to incorporate these green olefins in well-defined (co)polymers, we first established that methyl tiglate, the simplest tiglic acid ester, could not be polymerized using controlled polymerization techniques either, and we then introduced it in a methacrylate monomer, 2-(methacryloyloxy)ethyl tiglate (MAET), which could smoothly undergo group transfer polymerization (GTP) to yield linear polymers of narrow molecular weight distributions. Subsequently, amphiphilic and double-hydrophobic block copolymers, as well as a star polymer of MAET were obtained by its sequential GTP with 2-(dimethylamino)ethyl methacrylate, methyl methacrylate, and ethylene glycol dimethacrylate, respectively. Finally, polyMAET was selectively oxidized. © 2010 American Chemical Society. 43 3 1411 1415 Cited By :10

Semisegmented amphiphilic polymer conetworks (APCNs) based on the hydrophilic monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA), the hydrophobic monomer methyl methacrylate (MMA), and the hydrophobic cross-linker ethylene glycol dimethacrylate (EGDMA) were prepared using group transfer polymerization in a two-step procedure that involved the synthesis of linear polyDMAEMA or polyMMA arms, followed by their cross-linking using a mixture of EGDMA with either MMA or DMAEMA, respectively. Four semisegmented APCNs with polyMMA arms with degrees of polymerization (DPs) of 10, 20, 30, and 40 and three with polyDMAEMA arms with DPs of 10, 20, and 30 were prepared. The sol fraction extracted from the APCNs, the percentage of linear polymer in the sol fraction, and the molecular weights of the branched fraction of the extractables increased as the DP of the arms increased. The degrees of swelling (DSs) in water of all semisegmented APCNs increased with decreasing pH and increasing percentage of DMAEMA hydrophilic units. Despite the rather imperfect, semisegmented placement of the dissimilar units, extensive small-angle neutron scattering (SANS) experiments in D2O indicated that nanophase organization did take place within these APCNs and persisted, in many cases, even at full ionization of the hydrophilic monomer repeating units. The SANS profiles were also used to calculate the spacings between the scattering centers, which were found to increase with the content in the DMAEMA units and their degree of ionization. © 2009 American Chemical Society. 42 8 2972 2980 Cited By :24

Mutual diffusion coefficients and sorption isotherms of methyl methacrylate (MMA) and butyl acrylate (BA) monomers in methyl methacrylate-butyl acrylate copolymer (MMA-BA) have been measured by gravimetric sorption. MMA is found to have higher solubility and diffusion rates in the copolymer than BA. Sorption data for MMA were interpreted using classical Flory-Huggins thermodynamic theory with a constant interaction parameter (χ). A modified version of this theory has been applied to correlate the sorption data of BA, which exhibit a temperature and concentration-dependent χ parameter. For MMA, the isotherm data reveal enhanced polymer-solvent interactions with increasing temperature, while for BA the data indicate a drive toward phase separation with increasing temperature. Despite the difference in thermodynamic behavior, both monomers are found to exhibit Fickian diffusion and the diffusivity data are correlated reasonably well with the Vrentas-Duda free volume theory. Some deviation between the free-volume correlation and the experimental data is observed at the lowest temperature and BA concentration examined., TÜBİTAK and İYTE

cited By 0; International audience; The viscoelastic behavior of poly(methyl methacrylate) (PMMA) homopolymer and poly(methyl methacrylate-co-methyl acrylate) random copolymers was characterized by dynamic mechanical analysis and nanoindentation. Differential scanning calorimetric results showed only one glass transition, indicating the random distribution of comonomers in the copolymers. The a relaxation temperature (Tα) and activation energy (Hα) decreased with increasing content of methyl acrylate monomers (CMA%). The β relaxation temperature (Tβ) also decreased whereas the activation energy (Hβ) showed only small variations compared with Hα. Moreover, the indention displacement and creep compliance strongly depended on CMA%. Two creep stages were found in the creep compliance curves. Copyright © Taylor and Francis Group, LLC.

A binol ester initiator was used as a bifunctional ATRP initiator in combination with PMDETA/copper bromide catalyst system in DMF to synthesize n-butyl acrylate macroinitiator at 50� C. The resulting macroinitiator was used for a detailed investigation of the ATRP of methyl methacrylate (MMA) with CuCl/N,N,N?,N?,N?-pentamethyldiethylenetriamine (PMDETA) catalyst system in anisole at 30� C. Thus, the MMA polymerization is shown to proceed with first order kinetics, with predicted molecular weight and narrow polydispersity indices. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers synthesized. Copyright ? Taylor & Francis, Inc.

We present two novel, homologous, pyridine-based monomers, 2-(pyridin-2-yl)ethyl methacrylate (PyEMA) and (pyridin-2-yl)methyl methacrylate (PyMMA), which, despite their structural similarity, the former can be readily thermolyzed to methacrylic acid, while the latter remains intact under the same conditions. This was most dramatically demonstrated in the present work, where PyEMA and PyMMA were randomly terpolymerized with a dimethacrylate cross-linker using reversible addition-fragmentation chain transfer polymerization to yield weakly double-cationic polyelectrolyte hydrogels of three different compositions which, upon thermal treatment, they were readily converted to polyampholyte hydrogels. While the parent double-cationic polyelectrolyte hydrogels exhibited a swelling response only to low-pH conditions, the daughter polyampholyte hydrogels presented swelling responses to both high- and low-pH conditions. Owing to the relative values of the effective pKa's of the weakly acidic and weakly basic units, with the latter being lower than the former ("inverse polyampholyte" behavior), the swelling profiles of the daughter hydrogels were insensitive to polyampholyte composition. © 2014 American Chemical Society. 47 5 1819 1827 Cited By :11

We demonstrate the presence of Dirac cones in the dispersion relation of acoustic waves propagating on the surface of a plate of methyl methacrylate containing a honeycomb lattice of cylindrical boreholes. This structure represents the acoustic analogue of graphene, the cylindrical cavities playing the role of carbon atoms while acoustic surface waves are the equivalent of electronic waves in graphene. Analytical expressions for the Dirac frequency and Dirac velocity in acoustics are given as a function of the radius and depth of boreholes. These parameters have been experimentally determined for a constructed structure and the data are in fairly good agreement with the predicted values. © 2012 American Physical Society., Work supported by the Spanish Ministry of Science and Innovation (MICINN) under Contracts No. TEC2010-19751 and No. CSD2008-66 (CONSOLIDER program). Daniel Torrent acknowledges support from the program "Campus de Excelencia Internacional 2010 UPV." Both authors thank Didier Mayou for useful discussions.

Magnetoresponsive polymer-based fibrous nanocomposites belonging to the broad category of stimuli-responsive materials, is a relatively new class of “soft” composite materials, consisting of magnetic nanoparticles embedded within a polymeric fibrous matrix. The presence of an externally applied magnetic field influences the properties of these materials rendering them useful in numerous technological and biomedical applications including sensing, magnetic separation, catalysis and magnetic drug delivery. This study deals with the fabrication and characterization of magnetoresponsive nanocomposite fibrous membranes consisting of methacrylic random copolymers based on methyl methacrylate (MMA) and 2-(acetoacetoxy)ethyl methacrylate (AEMA) (MMA-co-AEMA) and oleic acid-coated magnetite (OA·Fe3O4) nanoparticles. The AEMA moieties containingβ-ketoester side-chain functionalities were introduced for the first time in this type of materials, because of their inherent ability to bind effectively onto inorganic surfaces providing an improved stabilization. For membrane fabrication the electrospinning technique was employed and a series of nanocomposite membranes was prepared in which the polymer content was kept constant and only the inorganic (OA·Fe3O4) content varied. Further to the characterization of these materials in regards to their morphology, composition and thermal properties, assessment of their magnetic characteristics disclosed tunable superparamagnetic behaviour at ambient temperature.

In this communication, we show that 2-(pyridin-2-yl)ethanol is a good protecting group for methacrylic acid (MAA), which can be selectively removed, after polymerization, either chemically under alkaline conditions or thermally at or above 110°C, while it is stable under acidic conditions and resists catalytic hydrogenolysis. To this end, the monomer 2-(pyridin-2-yl)ethyl methacrylate was synthesized, purified, and homo- and co-polymerized via two controlled polymerization methods, group transfer polymerization (GTP) and reversible addition-fragmentation chain transfer (RAFT) polymerization, to obtain homopolymers and diblock copolymers with methyl methacrylate (GTP) and styrene (RAFT), whose 2-(pyridin-2-yl)ethyl groups could be readily cleaved by chemical or thermal treatment, yielding diblock copolymers with polyMAA segments. The 2-(pyridin-2-yl)ethyl protecting group is one of the very few moieties that can be hydrolyzed under alkaline conditions, and, owing to the commercial availability and relatively low cost of 2-(pyridin-2-yl)ethanol, the present group is expected to find extensive use by the polymer community. © The Royal Society of Chemistry 2012. 3 12 3228 3231 Cited By :15

A new synthetic route for the preparation of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposites was reported. In this method, first 4-(dimethylamino)benzoate group was incorporated into silicate layers of clay by esterification reaction and used to produce PMMA/MMT nanocomposites by in situ Type II photoinitiated free radical polymerization. In situ photopolymerization of methyl methacrylate through into the silicate layers by either visible or UV light irradiation leads to PMMA/MMT nanocomposites. Copyright © 2011 Wiley Periodicals, Inc.

Isobornyl methacrylate (IBMA), a bulky hydropho- bic methacrylate, undergoes very fast polymerization, in bulk, with Cu(I)Br/N,N,N 0 ,N 00 ,N 00 -pentamethyldiethylenetriamine (PMDETA)/ethyl-2-bromoisobutyrate system, at ambient tem- perature. IBMA also undergoes a spontaneous initiator-free polymerization, at ambient temperature, with Cu(I)Br/PMDETA catalytic system in dimethyl sulfoxide-water mixtures. The rate of the polymerization is seen to increase with the water con- tent up to 80 mol % of water. A possible intervention of air in initiation is proposed. The active Cu(0) formed by the dispro- portionation of Cu(I) species in aqueous medium probably plays a vital role for a possible air-initiation of IBMA via single electron transfer-living radical polymerization (SET-LRP) mech- anism. A high tolerance level to water under SET-LRP condi- tions is demonstrated. The poly(IBMA) samples obtained exhibit low molecular weight distributions (1.1-1.3). Simi- lar behavior was not observed with other common methacry- lates such as methyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2165-2172, 2011

Dynamic mechanical-thermal analysis (DMTA), differential scanning calorimetry (DSC), thermally stimulated depolarization currents (TSDC) and, mainly, broadband dielectric relaxation spectroscopy (DRS) were employed to investigate in detail glass transition and polymer dynamics in silver/poly(methyl methacrylate) (Ag/PMMA) nanocomposites. The nanocomposites were prepared by radical polymerization of MMA in the presence of surface modified Ag nanoparticles with a mean diameter of 5.6 nm dispersed in chloroform. The fraction of Ag nanoparticles in the final materials was varied between 0 and 0.5 wt%, the latter corresponding to 0.055 vol%. The results show that the nanoparticles have practically no effect on the time scale of the secondary ß and ¿ relaxations, whereas the magnitude of both increases slightly but systematically with increasing filler content. The segmental ¿ relaxation, associated with the glass transition, becomes systematically faster and stronger in the nanocomposites. The glass transition temperature T g decreases with increasing filler content of the nanocomposites up to about 10 °C, in good correlation by the four techniques employed. Finally, the elastic modulus decreases slightly but systematically in the nanocomposites, both in the glassy and in the rubbery state. The results are explained in terms of plasticization of the PMMA matrix, due to constraints imposed to packing of the chains by the Ag nanoparticles, and at the same time, of the absence of strong polymer-filler interactions, due to the surface modification of the Ag nanoparticles by oleylamine at the stage of preparation. © 2011 Elsevier Ltd. All rights reserved., JLGR acknowledges the support of the Spanish Ministry of Science and Innovation through project No. EUI2008-00126 and funding in the Centro de Investigacion Principe Felipe in the field of Regenerative Medicine through the collaboration agreement from the Conselleria de Sanidad (Generalitat Valenciana), and the Instituto de Salud Carlos III (Ministry of Science and Innovation).

A novel initiator containing pyrene, a fluorescent moiety, was prepared by reacting 1-aminopyrene and 2-bromoisobutyl bromide. The structure elucidation of the new initiator was carried out using various spectroscopic tools, as well as through single crystal X-ray diffraction studies. Novel, fluorescent amphiphilic block copolymers with a pyrene end-group, poly(styrene-b-acrylic acid) [P(S-b-AA)], poly(methyl methacrylate-b-dimethylaminoethyl methacrylate) [P(MMA-b-DMAEMA)], poly(styrene-b-tert-butyl acrylate) [P(S-b-t-BA)], poly(styrene-b-dimethylaminoethyl methacrylate) [P(S-b-DMAEMA)] were successfully synthesized by the atom transfer radical polymerization (ATRP) method, using CuBr as the catalyst and N,N,N?,N?,N?- pentamethyldiethylenetriamine (PMDETA)/N,N,N?,N?,N?- hexamethyltriethylenetetramine (HMTETA) as the complexing agent. The polymers were characterized by GPC, 1H-NMR, IR and UV-Vis spectroscopies. It was observed that as the polymerization time increased, both the conversion and the molecular weight increased linearly with time. The fluorescence properties of the polymers prepared were recorded. The physical properties and especially the pH dependent swelling properties of the amphiphilic block copolymers have been investigated. The utility of the block copolymers in the formation of stable dispersion of cadmium sulphide nanoparticles was investigated as a model study. Copyright � Taylor & Francis Group, LLC.

Three series of conetworks based on cross-linked star polymers of different architectures were prepared using group transfer polymerization. The first series of conetworks were amphiphilic, based on the hydrophobic monomer benzyl methacrylate and the ionizable hydrophilic 2-(dimethylamino)ethyl methacrylate (DMAEMA) the second series were double-hydrophobic, based on methyl methacrylate and n-butyl methacrylate the third series were ampholytic, based on the negatively ionizable methacrylic acid (MAA) and the positively ionizable DMAEMA. The MAA units were introduced into the conetworks via the polymerization of tetrahydropyranyl methacrylate followed by its acid hydrolysis after network formation. All the precursors to the conetworks were characterized in terms of their molecular weights using gel permeation chromatography. The degrees of swelling (DSs) of all the conetworks were measured as a function of pH or in a mixture of solvents. Moreover, the effect of the architecture of the conetworks on the DS was investigated. The DS was found to be influenced more by the charge density of the conetwork than by the compatibility with the solvent, and more by the solvent compatibility than by the architecture of the conetwork. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. 291-292 1 36 42 Cited By :6

Four linear amphiphilic multiblock copolymers based on 2-(dimethylamino) ethyl methacrylate (DMAEMA, hydrophilic) and methyl methacrylate (MMA, hydrophobic), bearing from two to five blocks, were synthesized using reversible addition - fragmentation chain transfer polymerization and stepwise monomer additions. The degree of polymerization of each hydrophilic poly DMAEMA block was ~50, while that of the hydrophobic polyMMA blocks was ca. 20. The stepwise monomer addition procedure secured that each higher multiblock was composed of its immediately lower homologue plus exactly one extra block. The molecular weights (MW) of the synthesized (co)polymers, as measured by gel permeation chromatography (GPC), were close to the theoretically expected. GPC also indicated rather narrow molecular weight distributions which, however, broadened with the number of blocks. The compositions of the copolymers, as determined by proton nuclear magnetic resonance spectroscopy, were also close to the expected values. The cloud points of the copolymers, measured by turbidimetry, were found to increase with the number of blocks. The sizes of the micelles formed by the copolymers in aqueous solution were characterized using dynamic light scattering and small-angle neutron scattering. The determined values of the hydrodynamic radii, the radii of gyration, and the aggregation numbers of the micelles increased slightly with the block number from the triblock to the pentablock copolymer, implying extensive folding of the chains of the tetrablock and the pentablock copolymers in their micelles. The aggregation number of the tetrablock copolymer was approximately one-half that of the diblock copolymer whose unimer MW was onehalf that of the tetrablock, suggesting that the micellar cores of these two types of micelles were composed of the same number of hydrophobic units. © 2010 American Chemical Society. 43 6 2713 2720 Cited By :33

International audience; Microcellular foaming of commodity amorphous polymers, Polymethylmethacrylate (PMMA), and Polystyrene (PS) was studied in supercritical CO 2 via a one-step process in the presence of several types of additives able to change their foaming behaviour and therefore the porous structures. Additives such as diblock copolymers (styrene-co-methylmethacrylate SM) or triblock (styrene-co-butadiene-co-methylmethacrylate SBM, methylmethacrylate-co-butylacrylate-co-methylmethacrylate MAM) terpolymers, core-shell particles (methylmethacrylate styrene) were added to PS or PMMA by extrusion. They showed advantages compared to classical PS-PMMA polymer blends in terms of cell size control and reduction of cell size. Foaming is carried out on bulk injection molded samples which were saturated under high pressures of CO 2 (300 bars) at different temperatures (25°C to 80°C) and different depressurization rates (from 150bar/min to 12bar/min). Then very distinct cellular structures and densities were controlled by varying either the additive type or the foaming conditions, using different foaming temperatures and foaming times. Cell sizes are ranging from 0.2 μm to 200 μm, and densities from 0.30 g/cm3 to 1 g/cm 3 in the polymers considered. It was found that the some additives, well dispersed inside the polymer matrix, play an important role as nucleating agents, reducing drastically the average cell size, and improving the foaming process.

Tetrahydrofurfuryl methacrylate (THFMA), a heterocyclic monomer was polymerized by ambient temperature Atom Transfer Radical Polymerization (AT ATRP) using CuX/PMDETA/EBiB system. THFMA was found to undergo very rapid polymerization, in bulk. For a target DP > 200, bulk polymerization results in cross-linking as evidenced by (CH2)n,wag peaks (IR spectroscopy). Atom Transfer Radical copolymerization (ATRcP) of THFMA with MMA was performed and the reactivity ratios were calculated from the copolymer composition, as determined by 1H NMR, using Fineman-Ross and Kelen-Tudos methods. The reactivity ratios determined for ATRP were found to be significantly different from the literature values for conventional free radical polymerization (CFRP). This may be due to the coordination of copper catalytic system with the oxygen atom of the tetrahydrofurfuryl group that could lead to the variation in reactivity ratios. 1H NMR evidence for catalyst-monomer interaction is also provided. � 2009 Elsevier Ltd. All rights reserved.

Five linear amphiphilic multiblock copolymers based on 2-(dimethylamino) ethyl methacrylate ("D") and methyl methacrylate ("M"), bearing from two to six blocks, were synthesized using sequential group transfer polymerization. All copolymers were obtained from the same polymerization flask (by the withdrawal of a sufficient amount of sample and appropriate adjustment of subsequent monomer loadings) to ensure better comparison between the various multiblocks. A theoretical degree of polymerization (DPth) of 20 was targeted for all D blocks, whereas a DPth of 10 was aimed for the M blocks. Upon characterization using gel permeation chromatography and H NMR spectroscopy, the copolymers were confirmed to have the expected values of molecular weights and compositions. Subsequently, the aqueous micellization behavior of these copolymers was probed using dye solubilization, dynamic light scattering, and small-angle neutron scattering. Dye solubilization experiments indicated that micelles readily formed at low copolymer concentrations equal to or less than 0.03% w/w. The scattering measurements revealed that despite the differences in their overall DPth values, the triblock, the tetrablock, and the pentablock copolymers selfassembled in water to form micelles with radii of gyration and hydrodynamic radii very similar to each other, suggesting chain looping and the formation of flowerlike micelles, which is in agreement with recent Monte Carlo simulations. © 2009 American Chemical Society. 42 15 5492 5498 Cited By :28

Mixtures of two cleavable dimethacrylate crosslinkers, the hydrolyzable di(methacryloyloxy-1-ethoxy)methane (DMOEM) and the thermolyzable 1,1-ethylenediol dimethacrylate (EDDMA), were used for the preparation of neat crosslinker polymer networks, randomly crosslinked polymer networks of methyl methacrylate (MMA), and star polymers of MMA, using group transfer polymerization in tetrahydrofuran (THF). All star polymers and randomly crosslinked polymer networks containing mixtures of the hydrolyzable DMOEM and the thermolyzable EDDMA crosslinkers gave THF-soluble final products when subjected to sequential thermolysis and hydrolysis, in this order. When applying sequential hydrolysis and thermolysis, only the star polymers with an EDDMA crosslinker content equal to or higher than 50% gave THF-soluble final products. © 2009 Wiley Periodicals, Inc. 47 21 5853 5870 Cited By :1

The polymerization of methacrylic monomers present in dental composite resins never reaches completion and therefore the leakage of residual monomers into the oral cavity and into biological fluids can cause local and systemic adverse effects. This work was carried out to study the in vitro biochemical interactions of urethane dimethacrylate and 1,4-butanediol dimethacrylate monomers with HL-60 cells, a cell line assumed as an experimental model for simulating granulocyte behaviour. Our main finding was that both monomers induce cell differentiation at toxic concentrations and that cytotoxicity seems to be caused by alterations of glucose metabolism arising from mitochondrial dysfunction rather than from oxidative stress, which could not be altogether verified under our experimental conditions. Our study could be considered as a useful approach to investigate the biochemical mechanisms that contribute to the cytotoxicity of methacrylate compounds and it underlines the importance of assessing such parameters for testing biocompatibility in order to promote the development of better and safer dental materials.

The steady state burning rate of vertically oriented slabs of poly-methyl-methacrylate (PMMA) is numerically investigated. Model predictions are compared with measurements and results of the laminar boundary layer (LBL) theory. The numerical model provides a solution of the Favre-averaged Navier-Stokes equations coupled with sub-models for turbulence, combustion, soot production and radiation. The modelling of condensed phase processes is based on the one-dimensional heat transfer equation and pyrolysis is treated as a phase change using the latent heat approach. Results show that the pyrolysing region can be divided into three regions. In the laminar part of the flow (Grx < 4.3 × 107), the predicted normalised burning rate, m″px/μ∞, is a power-law function of Grx with an exponent close to that of the LBL theory, surface re-radiation being the primary source of discrepancies. From the LBL theory for free flow, it is demonstrated that the local burning rate is inversely proportional to the shear velocity gradient. This is globally confirmed by numerical model results. At Grx < 4.3 × 107 the change in slope of the burning rate observed experimentally, which indicates the end of the laminar flow region, is reproduced numerically. From Grx = 2.5 × 109 model results show that the surface mass flux of pyrolyzate increases with x, in agreement with experimental data in literature.

Polyethylene glycol) (PEG)-containing quasi-model amphiphilic polymer conetworks (APCNs) were prepared by reversible addition fragmentation chain transfer (RAFT) polymerization using α,ω-bis(2-cyanoprop-2-yl dithiobenzoate)-PEG as a bifunctional RAFT macrochain transfer agent (macro-CTA) and stepwise additions of a hydrophobic monomer and a crosslinker (crosslinker: macro-CTA = 10:1, reaction time 24 h). Three different types of monomers, methyl methacrylate (MMA), n-butyl acrylate and styrene, were employed as the hydrophobic monomers, whereas ethylene glycol dimethacrylate, ethylene glycol diacrylate and 1,4-divinylbenzene served as the respective crosslinkers. PEG homopolymer hydrophilic quasi-model networks were also prepared by RAFT-polymerizing the three crosslinkers directly onto the two active ends of the PEG-based macro-CTA. From the three ABA triblock copolymers prepared, the MMA-containing one was obtained at the highest polymerization yields. The crosslinking yields of the three ABA triblock copolymers with the corresponding crosslinkers were higher than those of the PEG-based macro-CTA with the same crosslinkers. The degrees of swelling (DSs) of all conetworks were measured in water and in tetrahydrofuran (THF). The DSs of the APCNs in THF were higher than those in water, whereas the reverse was true for the DSs of the hydrophilic homopolymer networks. Finally, the aqueous DSs of the APCNs were lower than those of the corresponding hydrophilic homopolymer networks. © 2008 Wiley Periodicals, Inc. 46 22 7556 7565

Objectives Methacrylic compounds such as 2-hydroxyethyl methacrylate (HEMA), triethylene glycol dimethacrylate (TEGDMA) and bisphenol A glycerolate (1 glycerol/phenol) dimethacrylate (Bis-GMA) are largely present in auto- or photopolymerizable composite resins. Since the polymerization reaction is never complete, these molecules are released into the oral cavity tissues and biological fluids where they could cause local adverse effects. The aim of this work was to verify the hypothesis that the biological effects of HEMA, TEGDMA and Bis-GMA – at a non-cytotoxic concentration – depend on the interaction with mitochondria and exert consequent alterations of energy metabolism, GSH levels and the related pathways in human promyelocytic cell line (HL-60). Methods The biological effects of methacrylic monomers were determined by analyzing the following parameters: GSH concentration, glucose-6-phosphate dehydrogenase (G6PDH) and glutathione reductase (GR) activity, oxygen and glucose consumption and lactate production along with cell differentiation and proliferation. Results All monomers induced both cellular differentiation and decrease in oxygen consumption. Cells treated with TEGDMA and Bis-GMA showed a significant enhancement of glucose consumption and lactate production. TEGDMA and HEMA induced GSH depletion stimulating G6PDH and GR activity. Conclusions All the monomers under study affect the metabolism of HL-60 cells and show differentiating activity. Since alterations in cellular metabolism occurred at compound concentrations well below cytotoxic levels, the changes in energy metabolism and glutathione redox balance could be considered as potential mechanisms for inducing clinical and sub-clinical adverse effects and thus providing useful parameters when testing biocompatibility of dental materials.