Methyl Methacrylate In Presence Research Articles

Metal‐Free Atom Transfer Radical Polymerization of PVDF‐Based Block Copolymers Catalyzed by Organic Photoredox Catalysts

AbstractPoly(vinylidene fluoride) (PVDF) and its copolymers represent a class of electroactive fluoropolymers with very attractive piezo/ferroelectric properties that can be chemically modified to achieve high‐quality composites with improved properties. Here, the synthesis of poly(methyl methacrylate)‐b‐poly(vinylidene fluoride)‐b‐poly(methyl methacrylate) (PMMA‐b‐PVDF‐b‐PMMA) triblock copolymers via metal‐free light‐catalyzed atom transfer radical polymerization (ATRP) using organic photoredox catalysts (OPRC) and light of suitable wavelength is reported. Using benzoyl peroxide bearing an ATRP active group at both ends of the molecule, telechelic PVDF is synthesized, and is used as a macroinitiator in the metal‐free, light‐catalyzed ATRP in presence of methyl methacrylate (MMA), an OPRC, and light of suitable wavelength. Kinetic studies are performed by monitoring the monomer consumed in solution and by using 1H‐NMR to calculate the formation of the new PMMA blocks. Three of the five tested OPRC, operating through an oxidative quenching pathway, guarantee a good control over the polymerization, confirmed by the constant concentration of radicals during the process and by the linear growth of the conversion versus the percentage of monomer consumed. Chain extension reactions are also performed to prove chain‐end fidelity, as well as “light ON/light OFF” reactions to test the temporal control guaranteed by the external stimuli used to catalyze the polymerization.

Plastisisation of polyvinilchloride biofilms with palm oil oleine and methylmethacrylate as comonomer

Polyvinylchloride (PVC) is the second largest thermoplastics produced after polyethylene (PE), polypropylene (PP) and polystyrene (PS), especially for packaging, households, toys, and other commodity products. However when used for food packaging, PVC has to be plastisised using plastisisers (added upto 30%), which may not comply with safety requirements for food biofilms. Palm oil oleine (POO) is a nontoxic and edible triglyceride containing double bond and can be bounded onto PVC backbone in the presence of methylmethacrylate (MMA) as comonomer and benzylperoxide (BPO) as initiator. The PVC resin was dissolved in tetrahydrofurane (THF), added with POO, MMA and BPO, (in various compositions), under constant stirring in a reflux reactor. The reaction mixtures were then refluxed for 3 hours under nitrogen atmosphere at constant pressure 1 atm. Plastisised PVC films were obtained after casting the reaction mixtures on a glass plates, and dried under vacuum at constant temperature 40°C. Mechanical properties of the films were tested and their morphology were analysed under scanning electron microscope (SEM) and FTIR spectoscopy. Optimum clear and flexible PVC films was obtained when weight composition of the reaction mixture: PVC/MMA/POO/BPO: 2/0.5/0.5/0.35. Elongation at break of the optimum film was more than 95% higher, whereas the tensile strength was 60% lower when compare to those of pure casted PVC film. SEM analysis of the film surface also showed good homogenous morphology, whereas analysis of FTIR spectra of the films before and after exhausted washing in n-hexane, indicating 48.5% binding of MMA and POO in the PVC films.

Effect of in-situ modification of α-alumina nanoparticles on mechanical properties of poly(methyl methacrylate)-based nanocomposites for biomedical applications

In this study, the modification of α-alumina nanoparticles in the presence of methyl methacrylate (MMA) is utilized as an efficient method in order to enhance the compatibility of α-Al2O3 nanoparticles with poly(methyl methacrylate) (PMMA) matrix. This modification is an efficient method to improve the mechanical properties of PMMA for biomedical applications. Fourier-transform infrared (FTIR) spectroscopy and field emission scanning electron microscope (FESEM) analysis show that a proper interaction is formed between the modified α-Al2O3 nanoparticles and PMMA. Mechanical experiments and thermo-gravimetric analysis (TGA) are utilized to study the physical properties. The results indicate that the tensile strength of PMMA is improved by 11.4% using 2 wt% modified α-Al2O3 nanoparticles. Impact strength and hardness are significantly increased by 39.9% and 46.3%, respectively. The content of nanoparticles is more significant compared to injection process parameters on the mechanical properties of modified α-Al2O3 nanoparticles-reinforced PMMA nanocomposites based on the analysis of variance (ANOVA) tool of Taguchi approach.

Physical and Mechanical Properties of Methyl Methacrylate-Impregnated Wood from Three Fast-Growing Tropical Tree Species

Timber from plantation forests has inferior physical and mechanical properties compared to timber from natural forest because it is mostly from fast-growing tree species that are cut at a young age. Filling cell voids with methyl methacrylate (MMA) can improve the wood properties. The purpose of this study was to determine the physical and mechanical properties of MMA-impregnated wood from three fast-growing wood species, namely jabon (Anthocephalus cadamba (Roxb.) Miq.), mangium (Acacia mangium Willd) and pine (Pinus merkusii Jungh. & de Vriese). Wood samples were either immersed in MMA monomer or impregnated with it and then heated to induce the polymerization process. Jabon, which was the lowest density wood, had the highest polymer loading, followed by pine and mangium. The physical and mechanical properties of samples were affected by wood species and the presence of MMA, with higher-density wood having better properties than wood with a lower density. Physical and mechanical properties of MMA wood were enhanced compared to untreated wood. Furthermore, the impregnation process was better than immersion process resulting the physical and mechanical properties. Based on MOR values, the MMA woods were one strength class higher compared to untreated wood with regard to Strength Classification of Indonesian Wood.

Pursuit of electroconducting thermoplastic vulcanizates: activated charcoal-filled polypropylene/ethylene–propylene–diene monomer blends with upgraded electrical, mechanical and thermal properties

Conducting polymer blends are getting attention due to their demanding applications in static charge dissipation processes. In the current study, polypropylene (PP)– and ethylene–propylene–diene monomer-based nanocomposites, filled with varying loadings of intrinsically conducting activated charcoal (AC) nanoparticles, were blended in the presence of methyl methacrylate (MMA)-based compatibilizer and sulfur-based vulcanization system to prepare electroconducting thermoplastic vulcanizates (TPVs). Fourier-transform infrared spectroscopy, confirming successful grafting of MMA on PP chains, was employed to perform structural analysis of the samples. Relative distribution of filler in polymer and rubber phases, level of homogeneity of filler distribution and optimum state of filler dispersion were analyzed via scanning electron microscopy. Improved degree of crystallinity, thermal stability and other characteristic temperatures of the prepared specimens were determined via differential scanning calorimetry and thermogravimetric analysis. Increasing filler contents considerably improved tensile strength, stiffness, and hardness of the prepared TPVs. Doping of AC into electrically insulator TPVs turned them into almost a semiconducting material as indicated by significant enhancement in their electrical conductivity values.

Thermal and mechanical properties of gamma-irradiated prevulcanized natural rubber latex/low nitrosamines latex blends

ABSTRACTThermal and mechanical properties of blended radiation prevulcanized natural rubber latex (RVNRL) and low nitrosamines latex (LNL) were studied. RVNRL was blended with LNL at various composition ratios. From the tensile test, it was found that the optimum tensile value was attained at a total blending ratio of 70% RVNRL and 30% LNL. Latex blending with optimum tensile strength was then subjected to gamma irradiation at various doses with the presence and absence of methyl methacrylate (MMA) at 10 pphr. It was found that the gamma irradiation of latex blend with the presence of MMA could help increase further the tensile value. Composition of blending at a specific ratio and gamma irradiation at a specific dose has led to a significant improvement in the mechanical properties of the latex blend. The formation of grafting in the latex blend was characterized by Fourier transform infrared spectra (FTIR) spectroscopy and differential scanning calorimetry (DSC). FTIR spectroscopy confirmed that MMA could be grafted onto blended latex effectively under appropriate irradiation conditions. Two new peaks at 1731 and 1149 cm−1 were observed after irradiation, indicating the presence of an ester group from poly(methyl methacrylate) (PMMA), which was grafted onto rubber chains. This finding was proved by the presence of new Tg in DSC analysis. The increase in new Tg indicates the movement of grafting chains, which are tightly bound onto rubber chains.

Role of Radical Species in Salicylaldiminato Ni(II) Mediated Polymer Chain Growth: A Case Study for the Migratory Insertion Polymerization of Ethylene in the Presence of Methyl Methacrylate.

To date, an inconclusive and partially contradictive picture exists on the behavior of neutral Ni(II) insertion polymerization catalysts toward methyl methacrylate (MMA). We shed light on this issue by a combination of comprehensive mechanistic NMR and EPR studies, isolation of a key Ni(I) intermediate, and pressure reactor studies with ethylene and MMA, followed by detailed polymer analysis. An interlocking mechanistic picture of an insertion and a free radical polymerization is revealed. Both polymerizations run simultaneously (25 bar ethylene, neat MMA, 70 °C); however, the chain growth cycles are independent of each other, and therefore exclusively a physical mixture of homo-PE and homo-PMMA is obtained. A Ni-C bond cleavage was excluded as a free radical source. Rather a homolytic P-C bond cleavage in the labile aryl phosphine ligand and the reaction of low-valent Ni(0/I) species with specific iodo substituted N^O (Ar-I) ligands were shown to initiate radical MMA polymerizations. Several reductive elimination decomposition pathways of catalyst precursor or active intermediates were shown to form low-valent Ni species. One of those pathways is a bimolecular reductive coupling via intermediate (N^O)Ni(I) formation. These intermediate Ni(I) species can be prevented from ultimate decomposition by capturing with organic radical sources, forming insertion polymerization active [(N^O)Ni(II)-R] species and prolonging the ethylene polymerization activity.

Photopolymerization of Ricinodendron heudelotii oil and methyl methacrylate in presence and absence of iron(ΙII) oxalato complex as photoinitiator

In this work, the photopolymerization of Ricinodendron heudelotii (R. heudelotii) oil and methyl methacrylate in presence and absence of iron(III) tris(oxalato) ferrate(III) tetrahydrate (Fe[Fe(C2O4)3]·4H2O) (A) in N,N′-dimethylformamide under UV radiation of 254 nm at 40 °C has been studied. The rate of polymerization, R P, varies linearly with the inverse of [A] up to 6.5 × 10−4 mol L−1 and decreases above this concentration with the increase of [A]. The photoinitiator-free polymerization and polymerization in presence of the Fe(III) photoinitiator exhibit similar polymerization behavior. Thermal analysis of poly(R. heudelotii oil-co-MMA) was investigated by thermogravimetric analysis method. The thermal analysis was performed at five different heating rates. The poly(R. heudelotii oil-co-MMA) synthesized in the presence of the photoinitiator exhibits three stages of decomposition while two stages of decomposition pattern are prominent in photoinitiator-free polymers and for both polymers the main decomposition occurs at temperature range 300–500 °C. The apparent activation energy (E a) of the decomposition has been calculated by three non-isothermal methods of Flynn–Wall–Ozawa, Kissinger and modified Coats–Redfern.

Novel Approach to Synthesis of Monodisperse Polymeric Microspheres: Heterophase Polymerization of Styrene and Methyl Methacrylate in Presence of Water-Insoluble Functional PDMSs

Water-insoluble polydimethylsiloxanes (PDMSs) with functional organic substituents at the silicon atom are promising surface-active substances for the synthesis of monodisperse polymeric microspheres. In this regard a number of PDMS oligomers bearing different functional chain ends (amino, carboxylic and epoxy groups) were synthesized by conventional approaches. Solubility of PDMS in both the monomers (styrene (St) or methyl methacrylate (MMA)) and water as well as their surface-active properties at the water-toluene interface were investigated. Heterophase polymerization of St and MMA was carried out in the presence of functional PMDS and the resulting suspensions of polymeric microspheres were characterized using scanning electron microscopy (SEM). It was shown that the polymeric suspensions obtained have a very narrow particle size distribution and high stability in electrolyte solutions. The mechanism of the interfacial layer formation which explains the observed results is proposed.

Synthesis of ultrathin poly(methyl methacrylate) model coatings bound via organosilanes to zinc and investigation of their delamination kinetics.

Polymer coatings are widely used to protect metals from corrosion. Coating adhesion to the base material is critical for good protection, but coatings may fail because of cathodic delamination. Most of the experimental studies on cathodic delamination use polymers to study the corrosion behavior under conditions where the interfacial chemistry at the metal(oxide)/polymer interface is not well-defined. Here, ultrathin linear and cross-linked poly(methyl methacrylate) [PMMA] coatings that are covalently bound to oxide-covered zinc via a silane linker have been prepared. For preparation, zinc was functionalized with vinyltrimethoxysilane (VTS), yielding a vinyl monomer-covered surface. These samples were subjected to thermally initiated free radical polymerization in the presence of methyl methacrylate (MMA) to yield surface-bound ultrathin PMMA films of 10-20 nm thickness, bound to the surface via Zn-O-Si bonds. A similar preparation was also carried out in the presence of different amounts of the cross-linkers ethylene glycol diacrylate and hexanediol diacrylate. Functionalized and polymer-coated zinc samples were characterized by infrared (IR) spectroscopy, secondary ion mass spectrometry (SIMS), ellipsometry, and X-ray photoelectron spectroscopy (XPS). Coating stability toward cathodic delamination has been evaluated by scanning Kelvin probe (SKP) experiments. In all cases, the covalently linked coatings show lower delamination rates of 0.02-0.2 mm h(-1) than coatings attached to the surface without covalent bonds (rates ∼10 mm h(-1)). Samples with a higher fraction of cross-linker delaminate slower, with rates down to 0.03-0.04 mm h(-1), compared to ∼0.3 mm h(-1) without cross-linker. Samples with longer hydrophobic alkyl chains also delaminate slower, with the lowest observed delamination rate of 0.028 mm h(-1) using hexanediol diacrylate. For the coatings studied here, delamination kinetics is not diffusion limited, but the rate is controlled by a chemical reaction. Several possibilities for the nature of this reaction are discussed; radical side reactions of the oxygen reduction are the most likely path of deadhesion.

Resin Monomers Act as Adjuvants in Ni-induced Allergic Dermatitis in vivo

Resin monomers (RMs) are inflammatory agents and are thought to cause allergic contact dermatitis (ACD). However, mouse models are lacking, possibly because of the weak antigenicities of RMs. We previously reported that inflammatory substances can promote the allergic dermatitis (AD) induced by intradermally injected nickel (Ni-AD) in mice. Here, we examined the effects of RMs on Ni-AD. To sensitize mice to Ni, a mixture containing non-toxic concentrations of NiCl2 and an RM [either methyl methacrylate (MMA) or 2-hydroxyethyl methacrylate (HEMA)] was injected intraperitoneally or into ear-pinnae intradermally. Ten days later, a mixture containing various concentrations of NiCl2 and/or an RM was intradermally injected into ear-pinnae, and ear-swelling was measured. In adoptive transfer experiments, spleen cells from sensitized mice were transferred intravenously into non-sensitized recipients, and 24 h later NiCl2 was challenged to ear-pinnae. Whether injected intraperitoneally or intradermally, RM plus NiCl2 mixtures were effective in sensitizing mice to Ni. AD-inducing Ni concentrations were greatly reduced in the presence of MMA or HEMA (at the sensitization step from 10 mM to 5 or 50 µM, respectively, and at the elicitation step from 10 µM to 10 or 100 nM, respectively). These effects of RMs were weaker in IL-1-knockout mice and in macrophage-depleted mice. Cell-transfer experiments in IL-1-knockout mice indicated that both the sensitization and elicitation steps depended on IL-1. Challenge with an RM alone did not induce allergic ear-swelling in mice given the same RM + NiCl2 10 days before the challenge. These results suggest that RMs act as adjuvants, not as antigens, to promote Ni-AD by reducing the AD-inducing concentration of Ni, and that IL-1 and macrophages are critically important for the adjuvant effects. We speculate that what were previously thought of as “RM-ACD” might include ACD caused by antigens other than RMs that have undergone promotion by the adjuvant effects of RMs.

RAFT-mediated one-pot aqueous emulsion polymerization of methyl methacrylate in presence of poly(methacrylic acid-co-poly(ethylene oxide) methacrylate) trithiocarbonate macromolecular chain transfer agent

The polymerization-induced self-assembly of amphiphilic block copolymers in water was performed following a reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization mechanism in emulsion. Poly(methacrylic acid-co-poly(ethylene oxide) methyl ether methacrylate), P(MAA-co-PEOMA), with a trithiocarbonate reactive end-group was selected as the water-soluble living precursor and synthesized in situ via a RAFT aqueous solution polymerization process. The study focused on the polymerization of methyl methacrylate (MMA) at pH 3.5, 5 and 7 and its copolymerization with various proportions of styrene (S) at pH 3.5. In the homopolymerization of MMA, the reaction was well-controlled at pH 3.5, while a low blocking efficiency was observed at higher pH. The systems led to spherical micelles, fibers and then vesicles when the molar mass of the hydrophobic block was increased, irrespective of the pH of the aqueous phase. In the case of the copolymerization with styrene at pH 3.5 and in chain length conditions leading to fibers for the homopolymerization of MMA, the control was very good but the final morphology was that of spherical particles only, at all compositions studied, exactly like in the homopolymerization of styrene performed under similar experimental conditions [Zhang et al. Macromolecules 2011; 44:7584–93]. The results were interpreted on the basis of an influence of the polymerization kinetics, especially in the early stage of the reaction in the aqueous phase.

Synthesis and electrical conductivity evaluation of novel hybrid poly (methyl methacrylate)/titanium dioxide nanowires

This work aims at preparation, characterization and electrical conductivity evaluation of novel poly (methyl methacrylate), PMMA, based nanocomposites. The sodium titanate nanowire (Na2TinO2n+1) was prepared using titanium dioxide nanoparticles via hydrothermal treatment method. The hybrid PMMA nanocomposites were prepared by in situ emulsion polymerization of methyl methacrylate in presence of cetyl trimethyl ammonium bromide and potassium persulfate as a cationic surfactant and initiator, respectively. In addition to, PMMA/polyaniline (PA)-based nanocomposites were obtained by adding sodium titanate nanowires and/or silver nitrate nanoparticles into the polymer mixture. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction pattern (XRD) and infrared spectroscopy (FT-IR) were used to characterize the structures of the nanocomposites. The resultant nanocomposites exhibited core–shell structure. Moreover, the conductivity of the prepared hybrid PMMA nanocomposites was increased from 1.32×10−8 to 5.9×10−5scm−1 with an increasing of the titanium dioxide nanowires concentration.

Methyl methacrylate‐assisted dyeing of polyamide microfibre

Polyamide microfibres were dyed using disperse dye in the presence and absence of methyl methacrylate. The dye uptake and colour strength in the presence of methyl methacrylate were substantially higher than in its absence. Scanning electron microscope analysis showed that there was a dye layer on the microfibre surface formed by methyl methacrylate adsorption after dyeing. Differential scanning calorimetry measurement showed that the glass transition temperature of the polyamide microfibre reduced following methyl methacrylate treatment. The ultimate consequence of all these functions was to facilitate diffusion of dye molecules into the microfibre, thereby increasing the colour strength. The wash fastness of the dyed samples was identical for the two different dyebaths, although there were slight differences in the staining grades. The rub fastness of the methyl methacrylate-treated samples was improved by ca. half a grade. The methyl methacrylate had no effect on light fastness.

Two‐Dimensional Chromatographic Analysis of Polystyrene‐block‐poly(methyl methacrylate) Copolymers Synthesized by Selective Oxidation of Polystrene‐9‐borabicyclo[3.3.1]nonane

AbstractSummary: The preparation of polystyrene block methyl methacrylate copolymers (PS‐b‐PMMA) is described. The polystyrene segment was prepared by anionic polymerization and the methylmethacrylate segment was prepared via free radical autoxidation of a borane agent attached to the styrene chain.1 The chemistry involves a transformation of the anionic polymerization process to borane chemistry by firstly producing polystyrene with chain end unsaturated alkyl functional groups prepared using a n‐butyllithium initiator and termination with allylchlorodimethylsilane. Secondly, the unsaturated macroinitiator end was hydroborated by 9‐borabicyclo[3.3.1]nonane (9‐BBN) to produce a borane terminated PS. Thirdly, the borane group at the chain end was selectively oxidized and converted to polymeric radicals in the presence of methyl methacrylate which then initiated radical polymerization to produce block copolymers. The polymer obtained was characterized using several chromatographic techniques including LC‐CC (liquid chromatography under critical conditions) for the polystyrene segments and two‐dimensional chromatography with LC‐CC in the first dimension and SEC in the second. The results show that block formation was successful although significant homopolymerization of methyl methacrylate is also obtained.

Mikto-Arm Star Copolymers with Hyperbranched Core Structure: Synthesis by Combination of Living Radical and Condensation Polymerization

Living free-radical copolymerization of the inimer 4-vinylbenzyl N,N-diethyldithiocarbamate with maleic anhydride in the presence of methyl methacrylate produces highly branched poly(methyl methacrylate) star polymers. Subsequently, mikto-arm stars can be synthesized by condensation of poly(ethylene glycol methyl ether) monosodium alkoxide with functional maleic anhydride sites in the hyperbranched core. The solution properties of these mikto-arm star copolymers are discussed.

Isothermal and non-isothermal polymerization of methyl methacrylate in presence of multiple initiators

Methyl methacrylate (MMA) polymerization is a diffusion-controlled reaction, characterized by a strong gel effect, which may cause uncontrolled heat generation and the thermal runaway of the process. For applications to industrial polymerization, kinetic control is particularly important and difficult to achieve due to the interplay between heat development and diffusional control occurring during polymerization. Sustaining the polymerization reaction (i.e. enhancing heat exchange) is a promising strategy to control MMA polymerization kinetics. In particular, different initiators triggering polymerization at different times can be used, thus reducing the possibility of thermal runaway by engineering temperature history and initiator nature/concentrations. There are few models accounting for the presence of multiple initiators and non-isothermal conditions. Therefore, a new, simple semi-empirical model, relating degree of conversion and polymerization rate to time and temperature, was developed. To validate the model, DSC tests were performed in isothermal and non-isothermal conditions, thus deriving the heat developed during polymerization. Model parameters were calculated from isothermal DSC experiments, and the model was predictive of monomer conversion in non-isothermal conditions in presence of single initiators and the mixture of them. Results indicate that, by varying formulation parameters (temperature history and initiator concentrations), polymerization kinetics may be optimized.

Preparation and characterization of polymer/silica nanocomposites via double in situ miniemulsion polymerization

Polymer/SiO2 nanocomposite microspheres were prepared by double in situ miniemulsion polymerization in the presence of methyl methacrylate, butyl acrylate, γ-methacryloxy(propyl) trimethoxysilane, and tetraethoxysilane (TEOS). By taking full advantage of phase separation between the growing polymer particles and TEOS, inorganic/polymer microspheres were fabricated successfully in a one-step process with the formation of SiO2 particles and the polymerization of organic monomers taking place simultaneously. The morphology of nanocomposite microspheres and the microstructure, mechanical properties, thermal properties, and optical properties of the nanocomposite films were characterized and discussed. The results showed that hybrid microspheres had a raspberry-like structure with silica nanoparticles on the shells of polymer. The silica particles of about 20 nm were highly dispersed within the nanocomposite films without aggregations. The transmittance of nanocomposite film was comparable to that of the copolymer film at around 70–80% from 400 to 800 nm. The mechanical properties and the fire-retardant behavior of the polymer matrix were improved by the incorporation of silica nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3128–3134, 2010

In vitro cytocompatibility evaluation of a thermoresponsive NIPAAm-MMA copolymeric surface using L929 cells

Scaffold free tissue constructs are preferred in tissue engineering as they overcome all the problems associated with scaffolds. Stimuli responsive polymers enable generation of scaffold free multilayered tissue constructs which would in turn reduce the use of biomaterials in vivo. In this study, we investigated cytocompatibility and thermoresponsiveness of a copolymer of N-Isopropylacrylamide and Methyl Methacrylate. Thermoresponsive surfaces were prepared by coating tissue culture polystyrene with the copolymer solution in isopropanol. Mammalian fibroblast cells (L929 cells) readily adhered on the copolymer. The viability and cellular activity was ensured through Neutral red staining, MTT assay, Tritiated thymidine uptake assay and Immunofluorescent staining for cytoskeletal organisation. Incubation under lower critical solution temperature of copolymer resulted in intact detachment of cells. To conclude, in-house synthesized cytocompatible smart culture substrate intended for tissue engineering was developed using a cost effective and simple technique. Moreover, presence of methyl methacrylate in the copolymer reduced the lower critical solution temperature facilitating extended in vitro manipulation time. As the copolymer is insoluble in water, the copolymer could be polymerised without additional crosslinkers.

Multifunctional hybrid materials based on transparent poly(methyl methacrylate) reinforced by lanthanoid hydroxo clusters

Three pentanuclear lanthanoid hydroxo clusters of composition [Ln(OH)(5)(abzm)(10)], where Ln = Eu, Tb, Ho and abzm = di(4-allyloxy)benzoylmethanide, have been prepared. The structures have been characterised by means of IR, Raman, elemental analyses and X-ray diffraction, showing a pyramidal square-based cluster core. The clusters (Tb and Ho) exhibit Curie-Weiss Law behaviour, displaying antiferromagnetic ordering at low temperatures. The emission properties of the Eu cluster demonstrate the abzm(-) ligand is an efficient antenna (λ(ex) = 420 nm) only for the sensitisation of Eu luminescence in the visible range, via energy transfer to the (5)D(0) state of the trivalent metal. The clusters have been reacted in the presence of methyl methacrylate and azobisisobutyronitrile to prepare reinforced polymers via radical polymerisation. The obtained materials exhibit swelling upon immersion into organic solvents up to ≈ 110% of their original size, in agreement with the presence of cluster-crosslinked polymeric chains. Also, no loss of transparency was observed in the preparation of the materials. The characteristic red emission of the Eu cluster in also retained in the polymeric material.