Poly Methyl Methacrylate Matrix Research Articles

A new tactics to fabricate flexible nanobelts with enhanced magnetic–luminescent bifunction

Novel magnetic–photoluminescent bifunctional [Fe3O4@Y2O3:Eu3+]/polymethyl methacrylate (PMMA) flexible composite nanobelts were successfully prepared by electrospinning via dispersing Fe3O4@Y2O3:Eu3+ core–shell structured nanoparticles (NPs) into the PMMA matrix. The morphology, structure and properties of the flexible composite nanobelts were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and fluorescence spectroscopy. The width and thickness of [Fe3O4@Y2O3:Eu3+]/PMMA composite nanobelts are 3.58 ± 0.29 and 1.2 μm, respectively. Fluorescence emission peaks of Eu3+ in [Fe3O4@Y2O3:Eu3+]/PMMA flexible composite nanobelts are observed and assigned to the energy levels transitions of 5D0 → 7F0 (580 nm), 5D0 → 7F1 (533, 586, 592, 599 nm), 5D0 → 7F2 (612 nm) and 5D0 → 7F3 (629 nm) of Eu3+ ions. Compared with Fe3O4/Y2O3:Eu3+/PMMA nanobelts, [Fe3O4@Y2O3:Eu3+]/PMMA flexible composite nanobelts possess much stronger luminescent intensity. The as-prepared flexible composite nanobelts exhibit excellent magnetism and photoluminescent performance. The intensities of magnetism and luminescence of the flexible composite nanobelts can be simultaneously tuned by adjusting the amount of Fe3O4@Y2O3:Eu3+ NPs introduced into the nanobelts. The high performance [Fe3O4@Y2O3:Eu3+]/PMMA flexible composite nanobelts have potential applications in the fields of cell separation, magnetic resonance imaging, drug deliver and future nanodevices.

Radiation resistant metal decorated MWCNTs/PMMA nanocomposite films with enhanced thermomechanical properties

UV/O3 radiation and chemical resistant nanocomposite films of functionalized/metal decorated multiwall carbon nanotubes (MWCNTs) with polymethylmethacrylate (PMMA) are synthesized. Silver nanoparticles are decorated on the surface of UV/O3 functionalized MWCNTs by both reduction and in situ growth from AgNO3 aqueous solution. Microscopic studies reflect the better dispersion of UV/O3 functionalized/silver decorated MWCNTs in polymer matrix contributing in enhancement of thermal stability, thermomechanical strength, glass transition temperatures, and thermal conductivity of nanocomposites even at 0.25 wt% MWCNTs additions. The thermal stability of nanocomposite film (0.25 wt% loading), prepared by using a surfactant (Sodium dodecyl sulfate) is increased to about 27 � C while the thermomechanical properties are raised up to 76% at 100 � C. Thermal and thermomechanical behavior of pre- and post-UV/O3 irradiated nanocomposite films are compared with neat polymer. The results reveal that UV/O3 functionalized MWCNTs can effectively disperse the radiation and have a dramatic reinforcement effect on the nature of the degradation of PMMA matrix. POLYM. COMPOS., 00:000–000, 2014. V C 2014 Society of Plastics Engineers

Straightforward fabrication of stable white LEDs by embedding of inorganic UV-LEDs into bulk polymerized polymethyl-methacrylate doped with organic dyes

Stable white-emitting down-converted LEDs are straightforwardly prepared by bulk polymerization of an organic dye doped polymethyl-methacrylate (PMMA) shell directly on top of a highly efficient commercial blue-emitting InGaN LED. Our optimized polymerization procedure allows for extending the form factor of achievable luminescence converter (LUCO) material beyond the conventional thin film form and to directly produce devices with light bulb design. The selected organic dyes, the blue-emitting Coumarin 30 and a red-emitting diketopyrrolopyrrole derivative, exhibit high compatibility with the free radical polymerization reaction of the PMMA matrix and ensure high stability of the final hybrid device. The control of both the thickness of the PMMA shell and the concentration of the dopant dyes allow for fine tuning of the emission color of the LUCO LED and to obtain white light with CIE chromatic coordinates x = 0.32 and y = 0.33, with rendering index as high as 80. This simple and versatile procedure is not dye-exclusive and is therefore extendable to other molecular systems for color-tunable efficient solid-state lighting sources.

Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic. Part I: Morphological, mechanical and calorimetric characterization

Hyperthermia is a technique for destroying cancer cells which involves the exposition of body's tissue to a controlled heat, normally between 41℃ and 46℃. It has been reported that ferro- or ferrimagnetic materials can heat locally, if they are placed (after being implanted) under an alternating magnetic field, damaging only tumoral cells and not the healthy ones. The power loss produced by the magnetic materials can be dissipated in the form of heat. This phenomenon has to be regulated in order to obtain a controlled temperature inside the tissues. The material that was produced and characterized in this work is composed of two phases: a polymethylmethacrylate (PMMA) matrix in which a ferrimagnetic biocompatible/bioactive glass ceramic is dispersed. This composite material is intended to be applied as bone filler for the hyperthermic treatment of bone tumors. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO2-Na2O-CaO-P2O5-FeO-Fe2O3 and contains magnetite (FeO*Fe2O3) inside an amorphous bioactive residual phase. The composite material possesses structural, magnetic and bioactivity properties. The structural ones are conferred by PMMA which acts as filler for the bone defect or its damaged area. Bioactivity is conferred by the composition of the residual amorphous phase of the glass-ceramic and magnetic properties are conferred by magnetite crystals embedded in the bioactive glass-ceramic. The characterization involved the following tests: morphological and chemical characterization (scanning electron microscopy-energy dispersion spectrometry-micro computed tomography analysis), calorimetric tests and mechanical test (compression and flexural four point test). In vitro assessment of biological behavior will be the object of the part II of this work.

Charge-transfer complex of 4-cyano-5,6-diphenylpyridazine-3(2)selenone with picric acid: Infrared, Raman, spectrophotometric, and photostability studies

Change transfer complex of 4-cyano-5,6-diphenylpyridazine-3(2)selenone (CDS) was obtained by reacting of CDS with picric acid. The structure was confirmed by a number of spectral (IR, Raman, UV-Vis) methods. The activation parameters ΔE, ΔH, ΔS, and ΔG were obtained from the DTG diagrams using Coats-Redfern and Horowitz-Metzger methods. The photostability of 4-cyano-5,6-diphenylpyridazine-3(2)selenone (CDS) and its charge-transfer complex doped in polymethyl methacrylate(PMMA) matrix exposed to UV-Vis radiation was studied.

Photochemical synthesis of pyrene perfluoroalkyl derivatives and their embedding in a polymethylmethacrylate matrix: a spectroscopic and structural study

A photochemical approach to perfluoroalkyl derivatives of pyrene embedded in a PMMA matrix to obtain materials for optoelectronic applications.

Thermal and thermomechanical behavior of amino functionalized and metal decorated MWCNTs/PMMA nanocomposite films

The homogeneous nanocomposites (NC) films of amino modified and metal decorated multiwall carbon nanotubes (MWCNTs) with polymethylmethacrylate (PMMA) were synthesized through in‐situ free radical polymerization. Silver metal nanohybrids (Ag/MWCNTs) were prepared by two strategies, that is, reduction of metal salt in presence of sodium dodecyl sulfate and in‐situ growth from AgNO3 aqueous solution. The amino functionalization by ball milling enhanced the dispersion of MWCNT in monomer and produced a new class of radiation resistant NC. These synthesized films were characterized by FTIR, TGA, TEM, EDX, TC, DMA, and optical microscopy to ascertain their structural morphologies, thermal stability, and mechanical strength. Microscopic studies reflect the homogeneous mixing of amino functionalized and metal decorated MWCNTs in polymer matrix contributing in the enhancement of thermal stability, thermo‐mechanical strength, glass transition temperatures, and thermal conductivity of NC even at 0.25 wt% addition of modified nanofiller. The thermal stability of NC film at 0.25 wt% loading was increased around ≂50°C and the raise of thermo‐mechanical properties was observed up to 85% at 100°C in the presence of adsorbed surfactant. Thermal and thermomechanical behavior of pre and post UV/O3 irradiated NC films has been compared with neat polymer. The results revealed that amino modified nanofiller embedded network in polymer matrix can effectively disperse the radiation and has a dramatic reinforcement effect on the nature of degradation of PMMA matrix. POLYM. COMPOS., 35:1807–1817, 2014. © 2013 Society of Plastics Engineers

Effect of Acid Hydrolysis Conditions on the Properties of Cellulose Nanoparticle-Reinforced Polymethylmethacrylate Composites.

Cellulose nanoparticles (CNPs) were prepared from microcrystalline cellulose using two concentration levels of sulfuric acid (i.e., 48 wt% and 64 wt% with produced CNPs designated as CNPs-48 and CNPs-64, respectively) followed by high-pressure homogenization. CNP-reinforced polymethylmethacrylate (PMMA) composite films at various CNP loadings were made using solvent exchange and solution casting methods. The ultraviolet-visible (UV-vis) transmittance spectra between 400 and 800 nm showed that CNPs-64/PMMA composites had a significantly higher optical transmittance than that of CNPs-48/PMMA. Their transmittance decreased with increased CNP loadings. The addition of CNPs to the PMMA matrix reduced composite’s coefficient of thermal expansion (CTE), and CNPs-64/PMMA had a lower CTE than CNPs-48/PMMA at the same CNP level. Reinforcement effect was achieved with the addition of CNPs to the PMMA matrix, especially at higher temperature levels. CNPs-64/PMMA exhibited a higher storage modulus compared with CNPs-48/PMMA material. All CNP-reinforced composites showed higher Young’s modulus and tensile strengths than pure PMMA. The effect increased with increased CNP loadings in the PMMA matrix for both CNPs-64/PMMA and CNPs-48/PMMA composites. CNPs affected the Young’s modulus more than they affected the tensile strength.

Characterization of multiwalled carbon nanotube-polymethyl methacrylate composite resins as denture base materials

Most fractures of dentures occur during function, primarily because of the flexural fatigue of dentureresins. The purpose of this study was to evaluate a polymethyl methacrylate denture base material modified with multiwalled carbon nanotubes in terms of fatigue resistance, flexural strength, and resilience. Denture resin specimens were fabricated: control, 0.5 wt%, 1 wt%, and 2 wt% of multiwalled carbon nanotubes. Multiwalled carbon nanotubes were dispersed by sonication. Thermogravimetric analysis was used to determine quantitative dispersions of multiwalled carbon nanotubes in polymethyl methacrylate. Raman spectroscopic analyses were used to evaluate interfacial reactions between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Groups with and without multiwalled carbon nanotubes were subjected to a 3-point-bending test for flexural strength. Resilience was derived from a stress and/or strain curve. Fatigue resistance was conducted by a 4-point bending test. Fractured surfaces were analyzed by scanning electron microscopy. One-way ANOVA and the Duncan tests were used to identify any statistical differences (α=.05). Thermogravimetric analysis verified the accurate amounts of multiwalled carbon nanotubes dispersed in the polymethyl methacrylate resin. Raman spectroscopy showed an interfacial reaction between the multiwalled carbon nanotubes and the polymethyl methacrylate matrix. Statistical analyses revealed significant differences in static and dynamic loadings among the groups. The worst mechanical properties were in the 2 wt% multiwalled carbon nanotubes (P<.05), and 0.5 wt% and 1 wt% multiwalled carbon nanotubes significantly improved flexural strength and resilience. All multiwalled carbon nanotubes-polymethyl methacrylate groups showed poor fatigue resistance. The scanning electron microscopy results indicated more agglomerations in the 2% multiwalled carbon nanotubes. Multiwalled carbon nanotubes-polymethyl methacrylate groups (0.5% and 1%) performed better than the control group during the static flexural test. The results indicated that 2 wt% multiwalled carbon nanotubes were not beneficial because of the inadequate dispersion of multiwalled carbon nanotubes in the polymethyl methacrylate matrix. Scanning electron microscopy analysis showed agglomerations on the fracture surface of 2 wt% multiwalled carbon nanotubes. The interfacial bonding between multiwalled carbon nanotubes and polymethyl methacrylate was weak based on the Raman data and dynamic loading results.

Effect of miscibility and interaction on the properties of polymethylmethacrylate/aramid nanoblends

The generation of supramolecularly organized structures from intermolecular interaction motivated us to fabricate new miscible nanoblends of polymethylmethacrylate (PMMA) and aramid. The polyamide, prepared through the condensation of 1,5-diaminonaphthalene and 1,4-phenylenediamine with isopthaloyl chloride, was incorporated into PMMA matrix to produce completely miscible nanostructured blends via physical interlocking. The influence of polymer–polymer interaction on the macroscopic properties of blends were studied using mechanical testing, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Ample adhesion between the blend components revealed higher tensile strength in the range 51–58 MPa. The physical interaction of PMMA with varying aramid content altered blend morphology significantly, i.e. from ellipsoidal to circular realms having well-defined boundaries and knitted nanofibril network. Blends with 10–70 wt% aramid, thus, possessed exclusive patterns owing to nanolevel compatibility between two phases. Differential scanning calorimetry results also designated exclusively miscible blends with glass transition between 67–81°C, lower than that of pristine polymers. Ten percent gravimetric loss temperature (T10) increased from 465°C to 531°C with increasing aramid content from 10 to 70 wt%. Novel nanoblends holding spherical/cylindrical supramolecular arrangement, easy processing, and thermal and mechanical integrity can be potentially favorable in many industrial applications. Copyright © 2013 John Wiley & Sons, Ltd.

Indentation and scratch behavior of functionalized MWCNT–PMMA composites at the micro/nanoscale

Polymethylmethacrylate (PMMA) and functionalized multiwalled carbon nanotube (F‐MWCNT) based composite films were prepared using solution casting method. Nanoindentation and scratch measurements were carried out to study the influence of F‐MWCNT as the reinforcement on the mechanical properties of the composite at the sub‐micron scale. The composites were prepared with varying weight percentages of F‐MWCNT in the PMMA matrix. The composites containing an adequate amount (0.25 wt%) of F‐MWCNT was found to demonstrate the maximum nanomechanical properties, viz. hardness, elastic modulus, recovery index. Scratch resistance measured in terms of coefficient of friction, also showed maximum value for the PMMA composite reinforced with 0.25 wt% of F‐MWCNT. POLYM. COMPOS., 35:948–955, 2014. © 2013 Society of Plastics Engineers

Functionalization of Carbon Nanotubes and Polymer Compatibility Studies

Multiwalled carbon nanotubes (MWNTs) were oxidated and functionalized in order to determine the structural and chemical changes on their atomic bonding. MWNTs were oxidized in an aqueous solution of HNO3 (70%) and H2SO4 (95%) at 25 °C. Pristine and oxidized carbon nanotubes (ox-MWNTs) were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and thermogravimetrical analysis (TGA). MWNTs and ox-MWNTs were silane-functionalized and incorporated into a polymethyl-methacrylate (PMMA) matrix. The dispersion properties and interface interactions were studied for the composite materials. MWCNTs oxidation was performed and supported by Raman spectroscopy and FTIR results of disorder and defects in the carbon lattice; as well as change in the amount and type of chemical groups attached to the CNTs walls. Roughness areas visible in SEM images indicate Van der Waals interactions between CNTs and functionalization reagents. Control of the oxidation state can effectively direct molecular functionalization of a CNT sidewall. Composites showed good dispersion of filler; with the best one for oxidized-silane functionalized CNTs.

Self-biased cobalt ferrite nanocomposites for microwave applications

Oriented CoFe2O4 nanoparticles, dispersed in polymethyl methacrylate (PMMA) matrix, were fabricated by magnetophoretic deposition of functionalized nanocolloidal cobalt ferrite particles into porous alumina membrane. Their magnetic behavior exhibits an out-of-plane easy axis with a large remanent magnetization and coercitivity. This orientation allows high effective internal magnetic anisotropy that contributes to the permanent bias along the wire axis. The microwave studies reveal a ferromagnetic resonance at 46.5 and 49.5GHz, depending on the filling ratio of the membrane. Ansoft High Frequency Structure Simulator (Ansoft HFSS) simulations are in good agreement with experimental results. Such nanocomposite is presented as one of the promising candidates for microwave devices (circulators, isolators, noise suppressors etc.).

A New Promising Nucleating Agent for Polymer Foaming: Applications of Ordered Mesoporous Silica Particles in Polymethyl Methacrylate Supercritical Carbon Dioxide Microcellular Foaming

The introduction of inorganic particles to improve the cell morphology of polymeric foams has been studied for decades. To this end, identifying an ideal nucleating agent and understanding the methodology to control nucleation have always been the focus of this field. In this study, spherical ordered mesoporous silica (OMS) particles were synthesized and applied as a potential nucleating agent in polymethyl methacrylate (PMMA) supercritical carbon dioxide (scCO2) microcellular foaming. These particles were modified with a silane containing fluorine to enhance their affinity with scCO2. For comparison, solid silica (SS) particles with almost similar particle size and surface treatment have also been studied. It was found that both of them could be well dispersed in the PMMA matrix, and exhibited excellent heterogeneous nucleation performance during the foaming process. The addition of a nucleating agent greatly increased the cell density and decreased the average cell diameter, and more importantly, there was no increase in the bulk density. Compared to SS particles, OMS particles showed higher nucleation efficiency. The addition of 5.0 wt % of OMS particles reduced the average cell diameter of PMMA foam from 1.62 to 0.66 μm and increased the cell density from 2.3 × 1011 cells/cm3 to 3.7 × 1012 cells/cm3, while for the composite foams with a similar content of SS particles, the cell diameter and cell density are 1.19 μm and 6.12 × 1011 cells/cm3, respectively. We speculated that the mesoporous structure of OMS particles might trap the CO2 forming gas cavities. The pre-existing gas cavities resulted in a lower nucleation energy barrier. The superior nucleation effect of the OMS particles became more significant when the foaming process was conducted at low foaming temperature, low saturation pressure, and/or high pressure drop rate.

Functionalized styryl iridium(III) complexes as active second-order NLO chromophores and building blocks for SHG polymeric films

We studied the second-order NLO properties in solution of various Ir(III) acetylacetonate complexes bearing a substituted cyclometallated 4-styryl-2-phenylpyridine (ppy-4-styryl-R, with R = NEt2, OMe, H, NO2) with the EFISH technique. The dipole moments were evaluated by Density Functional Theory (DFT) calculations.We have also investigated the Second Harmonic Generation (SHG) of composite films based on the various cyclometallated Ir(III) complexes dispersed and oriented in a polymethylmethacrylate (PMMA) matrix.

A Facile Access to New Polymethylmethacrylate-Anchored Ferrocene Substituted Nickel(II) Unsymmetrical Schiff Base Complexes: Synthesis and Characterization

This paper discloses two new side-chain metallopolymers containing an unsymmetrical organometallic Schiff base complex of Ni(II) linked to a polymethylmethacrylate (PMMA) matrix. The neutral ferrocene substituted Schiff base complex 1, Ni{CpFe(η5-C5H4)-C(O)CH=C(CH3)N–o-C6H4N=CH-(2-O,5-OH-C6H3)} where (Cp = η5-C5H5), was synthesized via template reaction by condensation of the tridentate half-unit metalloligand Fc-C(O)CH=C(CH3)-N(H)-o-C6H4NH2 (Fc = ferrocenyl = CpFe(η5-C5H4)) with 2,5-dihydroxybenzaldehyde in the presence of nickel(II) acetate tetrahydrate. The binuclear Schiff base complex of Ni(II) containing an aromatic free hydroxyl group was reacted under basic conditions with PMMA to afford, upon trans-esterification reaction, metallopolymers 2 (complex 1 monomeric unit/PMMA = 1/5) and 3 (complex 1 monomeric unit/PMMA = 1/3). Elemental analysis, FT-IR, 1H and 13C NMR spectroscopies, and cyclic voltammetry were utilized to characterize the newly synthetized compounds. Surface morphology of the metallopolymer film of 2 was studied using atomic force microscopy.

Color-converting bilayered composite plate of quantum-dot–polymer for high-color rendering white light-emitting diode

Highly bright CuInS₂ quantum dots (QDs), whose emission is easily tuned in orange and greenish-yellow colors through manipulating the ZnS shelling procedure, are integrated with polymethyl methacrylate (PMMA) to obtain a free-standing composite plate of QD-polymer. The composite plate embedded with orange or greenish-yellow QDs is combined in a remote type with a blue light-emitting diode (LED). No color rendering index (CRI) value results when orange QDs are applied, whereas use of greenish-yellow QDs leads to a limited CRI of 72. A higher-color rendering QD-LED is demonstrated through a spectral extension by devising a unique bilayer-structured QD plate, where two types of QD are separately incorporated into each PMMA matrix, with a buffer layer of polymer blend inserted between them. The bilayered QD plate LED exhibits an improved CRI of 81, a high luminous efficacy of 71.2 lm/W at an input current of 20 mA, and exceptional high-stability luminescent characteristics against the variation of applied current.

Cyclometalated 4-Styryl-2-phenylpyridine Platinum(II) Acetylacetonate Complexes as Second-Order NLO Building Blocks for SHG Active Polymeric Films

The second-order nonlinear optical (NLO) properties of various Pt(II) acetylcetonate complexes bearing a substituted cyclometalated 4-styryl-2-phenylpyridine (ppy-4-styryl-R, with R = NEt2, OMe, H, NO2) were investigated in DMF solution on working with an incident wavelength of 1907 nm by the EFISH technique, whereas the dipole moments were determined by density functional theory (DFT) calculations. In addition, a Pt(II) complex with the ppy-4-styryl-NEt2 ligand, which was the most NLO efficient chromophore due to a particularly high dipole moment, was dispersed in a polymethylmethacrylate matrix and then oriented by poling to give a composite film characterized by a good and quite stable second harmonic generation (SHG) signal.

Rheology and conductivity of carbon fibre composites with defined fibre lengths

Rheological and electrical properties of polymer composites containing conductive fillers are influenced not only by the total content of the filler but also by the shape and dimensions of filler particles markedly. However, separate treatment of these two effects is often not feasible in composites prepared by melt mixing as the filler concentration affects the flow behaviour of the melt and, thus, has an effect on the final particles geometry. In this work, composites with polymethylmethacrylate matrix and short carbon fibres with defined lengths independent on the fibre concentration were prepared and their rheology and the electrical conductivity were investigated. A pronounced influence of the fibre length on the rheological and electrical properties of the composites was confirmed. Increasing the length of the fibres the rheological quantities were affected more significantly and simultaneously the percolation threshold was shifted to lower fibre volume fractions.

Failure of Fiber Reinforced Composite Archwires

The objective of this article is to investigate the mechanical properties and surface morphology of fiber-reinforced composite (FRC) wires. FRC (Optis) wire and a NiTi 0.016 in diameter were evaluated with a 3-point bending test on a universal testing machine at temperatures of 23±1oC and 37±1oC. The sample was cut to a size of 30mm and divided into 5 groups, each consisting of 6 specimens. Group 1, 2 and 5 were tested at 3.1-mm deflection, groups 3 and 4 at 1.5mm deflection. The hysteresis curves were compared and the surface morphology of the FRC wires was observed by SEM. Clear breakages occurred between fibers and Polymethylmethacrylate (PMMA) matrix union between 1.5-mm and 2.0-mm deflection. Before 1.5-mm, the wires showed no significant changes in their surface structure. The flexural load required to produce a deflection of 1.5 mm on NiTi was near double that for the FRC wires. ANOVA indicated differences (P .05). FRC wires displayed comparable load-deflection curves to NiTi until deflection of 2.0mm, whereas it could be considered a viable alternative to metallic wires during mild irregular alignment situations. Failure occurs due to fibers pullout and breakage at the fiber/composite matrix interface.