Poly Methyl Methacrylate Matrix Research Articles

Ethylene Methacrylate (EMA) Co-polymer Toughened Polymethyl Methacrylate Blends: Physico-mechanical, Optical, Thermal and Chemical Properties

Polymethyl methacrylate (PMMA) was blended with ethylene methacrylate (EMA) copolymer in different compositions by melt mixing technique using Haake Rheochord twin screw extruder. The physico-mechanical, thermal, optical and chemical properties of PMMA/EMA blends were investigated with special reference to the blend compositions. The impact strength of the blends was found to increase significantly with increase in EMA content, without affecting the optical properties significantly. Optical micrograph images of the blends reveals that the rubbery phase dispersed as domains in the continuous PMMA matrix at 5 and 10 wt. % addition of EMA. The PMMA/EMA, 80/20 blend was found to exist as co-continuous system. Attempts have been made to correlate changes in morphology with mechanical properties. The influence of chemical ageing and heat ageing on the mechanical performance of PMMA/EMA blends has been studied. Four composite models such as series model, parallel model, Hapin-Tsai and Kerner's model have been used to fit the experimental tensile strength, tensile modulus and surface hardness.

Synthesis and characterization of fluorescent magneto polymeric nanoparticles (FMPNs) for bimodal imaging probes

Novel bifunctional fluorescent magneto polymeric nanoprobes (FMPNs) were synthesized to provide simultaneous diagnostic information via magnetic resonance imaging (MRI) and optical imaging. FMPNs consist of ultra-sensitive magnetic nanocrystals that function as MR probes combined with Nile Red, which functions as a fluorescent probe. FMPNs were encapsulated by a nano-emulsion method in polyvinyl alcohol (PVA, 87–89% hydrolyzed) through a matrix of polymethyl methacrylate (PMMA). FMPNs exhibited excellent colloidal stability and monodispersity. The production of MR and optical images demonstrated that FMPNs have potential as dual-mode imaging agents.

Structural, electrical and percolation threshold of Al/polymethylmethacrylate nanocomposites

AbstractAluminum‐embedded polymethylmethacrylate (PMMA) composites were produced by using different aluminum concentrations in the polymer matrix. The aluminum particles were spherical with a particle size of 80 nm. The hot compression molding method in inert atmosphere for all the composites was used in their preparation. The PMMA matrix was analyzed using solution viscosimetry analysis and it did not evidence degradation of the PMMA matrix. The microstructure of the composites was examined with scanning electron microscopy (SEM). The electrical conductivity was measured as a function of the aluminum content and the composite fabricated with 10 vol.% aluminum presented a conductivity three order of magnitude higher than that of pure PMMA. The enhancement in conductivity can be explained by means of segregated percolation path theory and the experimental results are in agreement with the theoretical law. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

A light-induced photochromic nanoswitch capable of non-destructive readout via fluorescence emission: cluster vs. single-molecule excitation of dihydroindolizines

We have synthesized a prototype of a photochromic styrylquinolyl-dihydroindolizine (DHI), which forms a highly coloured and fluorescent betaine upon irradiation with lambda<400 nm. Embedding this photochromic DHI in a thin polymethyl methacrylate (PMMA) film permits the non-destructive readout via fluorescence at low temperature (77 K). Thus, either a non-destructive photoswitch or an information recording system becomes available. Both possibilities have been explored: image recording and read-out, as well as information storage (at 77 K) have been demonstrated. Cluster- and single molecule-fluorescence upon laser excitation (lambda=355 nm) of the styrylquinolyl-dihydroindolizine in a PMMA matrix, and the effect of fluorescence blinking has been observed.

Dielectric Response of Onion-Like Carbon-Based Polymethyl Methacrylate Composites

The dielectric properties of polymethyl methacrylate films with embedded onion-like carbon particles have been studied from 20 Hz to 1 MHz to investigate the structural relaxations of the composite material by varying the temperature between 240 and 520 K. The temperature behaviour of the complex permittivity at a given frequency is found to be strongly dependent on the nanocarbon concentration. A small effect of the onion-like carbon concentration on the beta transition of the polymer composite has been observed, which indicates that the included onion-like carbon particles do not block the rotational degrees of freedom of the ester groups along the polymer chains. By contrast, it has been found that embedding the nanocarbon fillers to the polymethyl methacrylate matrix changes significantly the alpha transition and the melting temperatures in a non-monoto-nous way.

Effect of polymer relaxation on dielectric spectroscopic study of polymer–ferroelectric liquid crystal composites

Polymethylmethacrylate (PMMA) and ferroelectric liquid crystal (P–FLC) composite films (~ 4 μm) with varying proportions of ferroelectric liquid crystal have been prepared and the dielectric response of the composite films as a function of wide frequency (100 Hz–10 MHz) and temperature (127–40 °C) have been analyzed. The dielectric spectra of such composite systems are considerably modified compared to those of the corresponding pure LC or PMMA materials. The observed paraelectric to ferroelectric transition temperature of the composites is found to be lower (~ 85 °C) compared to that of the pure LC system (~ 98 °C), which makes these composites technologically more significant. The P–FLC composites also exhibit higher relaxation frequency and smaller dielectric strength for the Goldstone mode compared to those of the corresponding pure FLC. Depending on the percentage of the constitute materials, the molecular dynamics of the composite materials changes. Dielectric contributions of both liquid crystal and PMMA matrix forming the composites have been analyzed on the basis of Havriliak and Negami function.

Highly Luminescent NIR-to-Visible Upconversion Thin Films and Monoliths Requiring No High-Temperature Treatment

A method is described for producing highly luminescent composite NIR-to-visible upconversion thin films, made from β-NaYF4:3%Er,17%Yb nanocrystals in a polymethyl methacrylate (PMMA) matrix, which require no postdeposition heat treatment. Nanocrystals are synthesized via a single-phase, high-boiling-point solvent method, which requires neither metal-trifluoroacetate precursors nor the use of autoclaves. Highly luminescent films are produced that can be varied in thickness down to dimensions approaching those of the nanocrystals themselves. The physical properties of the films are characterized by AFM and TEM, whereas the spectroscopic properties are characterized by NIR-to-visible confocal microscopy and by the time-dependence of upconversion luminescence following pulsed NIR excitation. It is shown that dispersal of β-NaYF4:3%Er,17%Yb nanocrystals in PMMA has no adverse effect on the intrinsic quantum efficiency of upconversion. By focusing the NIR pump beam (980 nm, cw) in the film, linear intensity res...

Size effect in magneto-optical properties of Co nanoparticle dispersed systems

Faraday rotation spectra of Co nanoparticles embedded in polymethylmethacrylate (PMMA) matrix were investigated by the theoretical and experimental approaches. Co nanoparticles were synthesized by means of the thermal decomposition method, which makes it possible to control the particle concentration without changing the particle size distribution. The amplitude of Faraday rotation is dependent on the particle concentration, and the Faraday rotation spectra show the blueshift accompanied by the decrease in size of Co nanoparticles. The experimental results of Faraday spectra were consistent with the calculation using the Maxwell-Garnett model which is considering the size-dependent free-electron contribution and size independent bound-electron contribution. It was found that the spectral shift was caused only by the size-dependent diagonal element in the dielectric constant tensor, which originates from the confinement of the free electrons in nanoparticles.

Photochromic Properties of Naphthopyrans – PMMA Thin Film

A class of naphthopyran derivatives (3a–10a) with electron-donating and electron-acceptor substituent is prepared by condensation of 1,2-diaryl-2-propyn-1-ol with β-naphthol in the presence of pyridinium para-toluenesulfonate (PPTS) as catalyst. All compounds go ring-opening isomerization in polymethylmethacrylate (PMMA) matrix with UV light irradiation (30 watt) and the maximum absorption of ring-opening isomers is at the range of 426–556 nm. Ring-opening isomers are completely back to ring-closing isomers when samples are kept in darkness, the bleach rate of ring-opening isomers in PMMA film increased significantly when temperature is more than 45°C. Fatigue testing showed that no significant change of optical density was detected after 10 cycles.

Conductance switching mechanism of Rose Bengal organic thin films in ambient conditions

The molecular thin films of Rose Bengal (RB) embedded in polymethyl methacrylate matrix are fabricated by using the spin-coating technique. The macroscopic current–voltage (I–V) characterization of the film shows that the RB molecule has two conductance switching states with a high ON/OFF ratio in ambient conditions. The infrared spectra indicate that intermolecular hydrogen bonds can form in the RB thin films after their hydrolysis in air. With the first-principles calculations, we demonstrate that the hydrogen bonds will be destroyed in concomitance with the conformational change when the RB molecule switches to its high-conductance state after applying a voltage.

Study of novel carbon fiber composite used exfoliated carbon fibers

One of the applications for carbon nanotubes (CNTs), CNT composite has been studied to reinforce of polymer. However, CNTs have not shown enough reinforced effect, because of poor dispersibility of itself and low purification. These characteristics are connected with the lowering mechanical strength in CNT's reinforced polymer composite. On the other hand, exfoliated carbon fibers (ExCFs) prepared through electrochemical processing were found to have unique morphology such as nanometer or sub-micrometer sized fibrils and well dispersibility. Fabrication of composite using its ExCFs was investigated. ExCFs changed in nanometer-sized fibrils by using ultrasonication and CNTs dispersed by using ultrasonication were compounded with polymethyl methacrylate (PMMA) in situ process through polymerization, and then their mechanical properties were examined. Flexural strength and elasticity of PMMA composite reinforced by ExCFs increased 166 and 171% respectively at addition of only 2.0 wt.% comparison with bulk PMMA. There was no significant aggregation in fracture surface, and homogeneous dispersion of ExCFs throughout the PMMA matrix was recognized. It was better than that of PMMA composite reinforced by CNTs. Homogeneous dispersion might be strongly related to mechanical properties. ExCFs might be expected to be applied to nano-composite instead of CNTs.

Photoinduced Electron Transfer and Enhancement of Photoconductivity in Silicon Nanoparticles/Perylene Diimide Composites in a Polymer Matrix

An inorganic−organic hybrid composite was prepared from a soluble N-dodecyl-N′-phenyl-3,4,9,10-perylenetetracarboxylic diimide (DOPP) and silicon nanoparticles (NPs). The silicon NPs were synthesized by a solution-phase method. Remarkable photoluminescence (PL) quenching was observed in the composite dispersed in a polymethyl methacrylate matrix. On the basis of the analysis of the PL quenching mechanism, it was demonstrated that a photoinduced electron transfer from silicon NPs to DOPP could occur in the composite. The photoconductivity of the composite was studied, and the photosensitivity enhancement of the composite was realized due to the photoinduced electron transfer between silicon NPs and DOPP.

Resonance dielectric dispersion ofTEA-CoCl2Br2 nanocrystals incorporated into the PMMA matrix

The dielectric properties ofTEA-CoCl2Br2 nanocrystals incorporated into the polymethylmethacrylate matrix within the frequency range of3 × 105–2.6 × 109 Hz in the temperature region of 90–300 K were investigated. The considerable difference inthe dielectric spectra of the nanocomposite compared to those of the bulk crystal and thepure polymer matrix was observed. The dielectric dispersion of the composite materialreveals a resonance type (resonance frequency was found to be near 1.3 GHz) and may bequalitatively explained as the result of piezoelectric resonance on the nanocrystals. Themodel interpretation of this phenomenon based on the forced-dumped oscillator ispresented.

Manifestation of second-order nonlinear optical effects in KTP and RTP nanocrystallites incorporated into polymer matrices

Strong second-order optical effects in KTiOPO 4 (KTP) nanocrystallites incorporated into polymethylmethacrylate (PMMA) matrices have been found. The maximally achieved value of the effective second-order susceptibility was equal to about 2.2 pm/V at laser wavelength 1320 nm and at liquid helium temperature (LHeT). It corresponds to concentration of the nanocrystallites of about 5.6% in weighting units. Incorporation of Rb ions and finally conversion to RbTiOPO 4 (RTP) nanocrystallites substantially reduces the effect. A similar decrease is observed when the PMMA matrix is replaced by polyvinylcarbazole (PVK) matrix.

Solution-Processed High-Efficiency Organic Phosphorescent Devices Utilizing a Blue Ir(III) Complex

We report high-efficiency blue phosphorescence organic light-emitting devices by solution process utilizing a blue Ir(III) complex [(F2ppy)2Ir(ph-imz)CN] (F2ppy = 2',6' -difluoro-2-phenyl pyridine and ph-imz = N-phenyl imidazole) blended with the host mCP (N, N'-dicarbazolyl-3,5-benzene), and the inert polymers polystyrene (PS) and polymethylmethacrylate (PMMA). The effects of the dopant confinement in the PS and PMMA matrix on the device performance are studied by field emission transmission electron microscopy (FE-TEM) and atomic force microscopy (AFM). The complex shows photoluminescence peaked at 458 nm with CIE color coordinates (0.14, 0.21) in solution and (0.14, 0.18) in doped PMMA film. The PS based device showed better device performance than the PMMA based device with a maximum luminous efficiency of (etaL) 5.11 cd/A with CIE color coordinates (0.17, 0.29) (at 10 mA/cm2) and a maximum luminance of 9765 cd/m2.

Effects of the molar mass of the matrix on electrical properties, structure and morphologyof plasticized PANI–PMMA blends

The effects of the molar mass of polymethylmethacrylate (PMMA) on electrical, structuraland morphological properties of conductive polyaniline–polymethylmethacrylateblends have been studied. We have plasticized the PMMA matrix by using dioctylphthalate (DioPh). Three different molar masses of PMMA, 15 000, 120 000 and350 000 g mol−1, have been used. The x-ray diffraction analysis showed amorphous structure for all our studiedPANI–PMMA blend films. The SEM micrographs showed more aggregation with the lowestmolar mass of PMMA matrix. The direct current (dc) and alternating current (ac) electricalconductivities have been investigated in the temperature range 20–300 K and frequency range7–1 × 108 Hz. The results of this study indicate an increase of the conductivity whenthe molar mass of PMMA decreases. With the lowest molar mass of PMMA(15 000 g mol−1), we obtained the lowest percolation threshold(pc≈0.3%). The dc conductivity is governed by Mott’s three-dimensional variablerange hopping (3D VRH) model; different Mott’s parameters have beenevaluated. At high frequencies, the ac conductivity follows the power lawσ(ω,T) = A(T)ωs(T,ω), which is characteristic for charge transport in disordered materials by hoppingor tunnelling processes. The observed decrease in the frequency exponents with increasing temperature suggests that the correlated barrier hopping (CBH) model bestdescribes the ac conduction mechanism. All our blends are well described by the scaling lawσ(ω)/σdc = 1+(ω/ωc)n with n≈0.51–0.52.

Study on preparation and fluorescence characteristic of coordinated Eu 2O 3/polymer hybrid films

The cyclohexane solution of TTA (trifluorothenoyl-acetone), phen (8-hydroxylquinoline) and PS (polystyrene), the ethyl acetate solution of TTA, phen and PMMA (polymethyl methacrylate) were used as flowing liquid, the coordinated Eu 2O 3/polymer hybrid colloids were successively produced by focused pulsed laser ablation of Eu 2O 3 target in interface of solid and flowing liquid. As solvent in the hybrid colloids has volatilized, the coordinated Eu 2O 3/polymer hybrid films were obtained. The hybrid colloids and films were characterized by TEM, UV–vis spectrum, fluorescence spectrum, TG-FTIR and X-ray photoelectron spectrum. The results show the coordinated Eu 2O 3 nanoparticles with average size of less than 20 nm are surrounded by the three-dimensional network and are properly incorporated into the PMMA and PS matrix, the hybrid films can emit intense red light under ultraviolet radiation, and their emission fluorescence spectra display same characteristic emission peaks of Eu 3+ ions. The Eu 2O 3 hybrid films have better thermo stability than the related pure polymers because of strong interaction between surface europium ions of the nanoparticles and polymer. Because the coordinated Eu 2O 3 nanoparticles were wrapped by polymer, they have higher chemical stability than the related europium complex.

Near-infrared luminescence properties of erbium complexes with the substituted phthalocyaninato ligands

Two homoleptic bis(phthalocyaninato) erbium(III) complexes Er[Pc(beta-OR/R)4]2 and two half-sandwich phthalocyaninato erbium(III) complexes (acac)Er[Pc(beta-OR/R)4] (OR = 1-n-pentyloxy and R = tert-butyl) have been investigated. Then we studied the near-infrared luminescence properties of the compounds. When the phthalocyanine ligands were excited, half-sandwich phthalocyaninato erbium(III) complexes showed strong near-infrared luminescence at 1540 nm while homoleptic bis(phthalocyaninato) erbium(III) complexes showed no signals. The full width at half maximum (FWHM) centered at 1540 nm in the emission spectrum of the half-sandwich complexes in solution and in solid state are 67 nm and 78 nm respectively, which shows potential for optical-amplification applications. Erbium-doped standard polymethyl-methacrylate (PMMA) matrix which was synthesized has also displayed NIR emission.

Influence of dyes doped in solid state polymeric matrices as spectral converters on efficiency of a flash-lamp pumped Nd:YAG laser

Organic dye materials doped in poly-methyl methacrylate matrix were used as spectral converters to increase the energy efficiency of a flash-lamp pumped Nd:YAG laser. In this process, the useless part of emitted spectrum from the pumping lamp is absorbed by dye molecules and, subsequently, re-emitted at longer wavelengths where the narrow absorption line of neodymium ion at about 580nm can be used more efficiently. As a result, approximately 40% enhancement in energy efficiency was achieved.

Interactions in organic rectorite composite gel polymer electrolyte

AbstractRectorite (REC) was modified with dodecyl benzyl dimethyl ammonium chloride (1227) to form an organic-modified rectorite, termed OREC. The OREC was used as a filler additive to modify gel polymer electrolytes (GPEs) which consisted of polymethyl methacrylate (PMMA), propylene carbonate (PC) and LiClO4. Studies of ionic conductivity and viscosity of liquid electrolytes and pure PC, respectively, clearly showed that these properties are greatly influenced by temperature and the amount of OREC added; a consequence of the interactions between the components of CPEs. The Fourier transform infrared (FTIR) spectroscopy results indicated that there were two kinds of interaction: namely (1) a strong hydrogen bond between Si–OH and C=O of PC and (2) a weak interaction between Li+ and C=O. Inverse gas chromatography (IGC) research supported the FTIR interpretation, indicating that the two interactions exist and that the H bond is the stronger of the two. In CPEs, the polymer matrix of PMMA merely supports the active components and does not influence the interactions between them. The OREC greatly increased the crucial plasticizer maintenance property when the amount of clay added was optimum.