Poly Methyl Methacrylate Core Research Articles

Design, fabrication and characterization of arrayed waveguide grating devices based on different polymers

1 × 8 and 1 × 16 traditional/saddle arrayed waveguide grating (AWG) devices with different core layer materials applied in fiber Bragg grating (FBG) system were designed, fabricated and compared. We applied epoxy resin-type materials (SU-8) and polymethyl methacrylate (PMMA) as the core layer materials, and polymer polydimethylsiloxane (PDMS) was selected as the cladding material. We developed a chemical modification method in order to improve the film-forming properties of the core layer materials on the PDMS cladding layers. The dimensions of the fabricated AWGs with SU-8 core layers and PMMA core layers were smaller than 1.1 cm × 0.9 cm and 1.1 cm × 1.2 cm, respectively. According to the experimental results, the on-chip insertion losses of 1 × 8 and 1 × 16 SU-8 AWG devices were lower than those of PMMA AWG devices with the same type of arrayed waveguides and the number of input and output channels, with 2.83-dB and 2.26-dB lower values of the 1 × 8 and 1 × 16 SU-8 AWG devices, respectively.

Preparation and Tracking of Oblate Core-Shell Polymethyl-Methacrylate Ellipsoids.

Although single-particle level studies on prolate ellipsoidal colloids are relatively abundant, similar studies on oblate ellipsoids are rare because suitable model systems are scarcely available. Here, we present the preparation of monodisperse hard core-shell oblate ellipsoids that can be imaged and tracked in 3D with confocal laser scanning microscopy. Using a thermomechanical squeezing method, we transform spherical core-shell polymethyl-methacrylate (PMMA) particles into oblate ellipsoids. We show how the shape polydispersity as well as the aspect ratio of the obtained oblate ellipsoids can be controlled. In addition, we discuss how the core-shell geometry limits the range of aspect ratios because of the different viscoelastic properties of the cross-linked PMMA core and linear PMMA shell. We further demonstrate imaging of the core-shell oblate dispersions on a single-particle level in real space and time and the tracking of position and orientation using our recently developed tracking algorithm for anisotropic core-shell colloids. Our results thus provide the tools for the future investigation of the behavior of oblate ellipsoids, especially in dense suspensions.

Development of nucleic acid isolation by non-silica-based nanoparticles and real-time PCR kit for edible vegetable oil traceability

For efficient extraction of amplifiable DNA from edible vegetable oils, we developed a novel DNA extraction approach based on the non-silica-based dipolar nanocomposites. The nanoparticle comprises a hydrophilic polymethyl methacrylate core with abundant capillaries, hydrophilic vesicles decorated with molecules having DNA affinity and a coating hydrophobic polystyrene layer. The nanoparticles are soluble in oil, adsorb the DNA from the aqueous phase and gave a high DNA recovery ratio. All DNA extracts from fully refined vegetable oil soybean, peanut, rapeseed, and cottonseed oils, including their blends, were sufficiently pure to be amplified by real-time PCR targeting the chloroplast ribulose-1,5-bisphosphate gene (rbcL), therefore, the species of origin and their ratios in mixed vegetable oils blended from two or three oil-species could be determined. These results indicate that the novel DNA isolation and real-time PCR kit is a simple, sensitive and efficient tool for the species identification and traceability in refined vegetable oils.

The effect of polymer particle size on three-dimensional percolation in core-shell networks of PMMA/MWCNTs nanocomposites: Properties and mathematical percolation model

Segregated highly conductive percolation networks in nanocomposites consisting of a polymethyl methacrylate (PMMA) core and multi-walled carbon nanotube (MWCNT)-shell were investigated experimentally as a means of exploring the relationship between the micro-dimensional size of spherical polymer particles and the number of coated MWCNT layers by a new theoretical approach of filler monolayer model. The measured electrical conductivity of the core-shell structured complex utilizing 20 μm PMMA spheres showed that percolation was achieved at a very low filler content of 0.0099 wt% MWCNTs, whereas 0.149 wt% MWCNT was required to achieve percolation when 5 μm PMMA spheres were utilized. The size of PMMA cores was attributed to the percolation threshold, and conductivity was enhanced by increased layers of MWCNT coating. The percolation behaviors based on the theoretical model and experimental data were elucidated. Furthermore, an advanced theoretical model for prediction of number of MWCNT monolayers was provided.

Preparation of Core-Shell Hybrid Compounds by Atomic Transfer Radical Polymerization and Its Application to Plastic Lens of Headlamp.

Nano silica ball (NSB) core polymethylmethacrylate (PMMA) shell hybrid nanocomposites were synthesized by atomic transfer radical polymerization (ATRP) method for the application to the clearcoat to enhance scratch resistance. The characteristics of the synthesized inorganic/organic hybrid material were examined by scanning electron microscope (SEM), particle size analysis, Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis-differential scanning calorimetry (TGA-DSC). The scratch resistance and light transmittance of the clearcoat were measured by a nano-scratch tester and UV-visible spectroscopy, respectively. The average particle size of the NSB-PMMA hybrid compounds was 30 nm with narrow size distribution. Even 0.1 wt% loading of NSB-PMMA in the clearcoat dramatically enhanced the scratch resistance, about 40% increase in the force of the first fracture, while slightly reduced the light transmittance, about 5% only.

Chemical bonding heterocoagulation of nanoparticles onto polymeric spheres by two-step addition of polymerizable coupling agent

Raspberry-shaped particles of a polymethylmethacrylate (PMMA) core chemically binding silica nanoparticles (NPs) could be synthesized with heterocoagulation in combination with two-step addition of a polymerizable silane coupling agent of 3-methacryloxypropylmethoxysilane (MPTMS) before and after the heterocoagulation, respectively. Submicron-sized PMMA particles were prepared in soap-free emulsion polymerization in the presence of MPTMS that was introduced into the PMMA particles as a scaffold for the chemical bonding. The PMMA particles were mixed with silica NPs under an acidic condition of pH = 2 to cause electrostatic heterocoagulation of the PMMA cores and the silica NPs. Then, MPTMS was added to the acidic suspension, and the suspension pH of heterocoagulated particles was raised to 8 to generate strong chemical bonding between the PMMA and silica NPs in stable particle dispersion. The strong interaction between the PMMA cores and silica NPs was demonstrated in sonication experiments where desorption of silica NPs from the PMMA cores was drastically suppressed by the two-step MPTMS addition.

Polymethylmethacrylate (PMMA)/CeO2 hybrid particles for enhanced chemical mechanical polishing performance

The organic/inorganic hybrid particles with polymethylmethacrylate (PMMA) spheres (350–360nm) as inner cores, and ceria nanoparticles (5–10nm) as outer shells were synthesized via electrostatic interaction. Chemical mechanical polishing (CMP) tests for silica films showed that the hybrid particles exhibited lower surface roughness, fewer scratches as well as lower topographical variations than those of solid ceria particles and (PMMA+CeO2) mixed particles. The improved CMP behavior might be attributed to the synergetic effect of the PMMA cores and the ceria shells. Furthermore, we discussed the material removal mechanism of hybrids in CMP process based on the proposal that the core/shell composite abrasives might be considered as micro-fixed abrasive pads.

Effect of buffer materials on thermal imprint on plastic optical fiber

We are advancing the development of a smart fiber using a plastic optical fiber (POF) as a fibrous substrate with micro-electro-mechanical-systems (MEMS) patterned on its surface. We employed hot embossing and thermal nanoimprinting techniques for patterning on the surface of POF, although, no work has so far been reported on the molding characteristic of POF. And moreover, achieving any high quality imprinted patterns on POFs has also proven to be difficult. We have been studying the effect of molding on POFs under various heating temperatures and press depths by sandwitching the POF between patterned face of a mold and a buffer material. When a soft buffer material with its hardness less than that of the polymethyl methacrylate (PMMA) core of a POF fiber was used, a reasonable patterning on the clad layer covering the surface of the POF was achieved without any sign of deformation of PMMA core. On the other hand, when the hardness of a buffer material happened to be equal to, or higher than that of the PMMA core, then deep concave pattern could be processed by purposefully deforming the POF. We successfully transferred a pseudo MEMS pattern with a width of 20 μm on the surface of a 250-μm-diameter POF. Also, under another kind of optimized molding conditions combined with buffer material, we fabricated an arc-shaped weaving guide structure on POF with the weaving guide`s bottom width of 300 μm. The investigation of the molding characteristic of POF by examining any change in the cross-sectional shape is a unique one. The experimental results thus obtained, add significantly to the database for the processing of a fibrous substrate by thermal deformation.

Soft patterning on cylindrical surface of plastic optical fiber

The authors have developed a novel thermal imprinting method to fabricate microstructures on the surface of plastic optical fibers (POFs) without causing any damage to them. In conventional thermal nanoimprinting using a planar mold, the shape of the molding material is in the form of a film spread on a planar substrate, or the molding material is used in its bulk form. In the case of any 3-dimensional shaped molding material such as in the case of a fiber, the shape becomes susceptible to a certain degree of damage caused by the planar mold. In order to address this problem, we have designed a thermal imprinting method using sliding planar molds. A fiber tightly stretched between two reel stations (for sending and winding of the fiber) is sandwiched between two planar molds facing each other. The fiber is then rolled against the pattern sides of the two planar molds while the rolling motion of the fiber remains synchronized with the sliding motion of the planar molds. The problem of twists in the fiber caused by the sliding planar molds was solved by dynamically rotating the two reel stations to match the rotation of the fiber. To demonstrate this technology, we employed a special electroformed-Ni mold with a mirror image of a string of characters forming the word “MACROBEANS” engraved in the form of a lattice, where the individual characters were composed of diffraction grating structures with 1 and 2 μm of linewidths. Using this mold, the cylindrical surface of a POF made of a 240-μm-diameter polymethyl methacrylate core with a coating of a 5-μm-thick fluoroplastic cladding was thermal-imprinted. From the observation of the imprinted patterns on the POFs, it was verified that the cylindrical surface was patterned without causing any damage to the POF. The height of the convex mold pattern was 1.1 μm, and the depth of the concave imprinted pattern was approximately 1.0 μm.

Polymer microspheres with structured surfaces

Microspheres from polymethyl methacrylate (PMMA) and Eudragit FS 30D (a commercial copolymer of poly(methyl acrylate- co-methyl methacrylate- co-methacrylic acid) 7:3:1) were prepared using microsieve emulsification. A mixture of these polymers in dichloromethane (DCM) was dispersed into water, leading to extraction of DCM in water and the formation of microspheres with a PMMA core and a partially demixed Eudragit shell. With a higher ratio of Eudragit to PMMA, more and bigger pores can be seen on the surface of the microspheres. Eudragit can be removed from the shell of the microspheres under alkaline conditions. Depending on the initial Eudragit to PMMA ratio, PMMA microspheres with different surface morphologies are obtained. At low Eudragit concentrations microspheres with a crumpled surface are formed, while at higher Eudragit concentrations microspheres are formed with a core to which dendritic PMMA structures are attached. At even higher Eudragit concentrations the microspheres obtained after dissolving the Eudragit show a nanorough surface.

Thiolated chitosan nanoparticles for enhancing oral absorption of docetaxel: preparation, in vitro and ex vivo evaluation

The aim of this study was to prepare and evaluate mucoadhesive core-shell nanoparticles based on copolymerization of thiolated chitosan coated on poly methyl methacrylate cores as a carrier for oral delivery of docetaxel. Docetaxel-loaded nanoparticles with various concentrations were prepared via a radical emulsion polymerization method using cerium ammonium nitrate as an initiator. The physicochemical properties of the obtained nanoparticles were characterized by: dynamic light-scattering analysis for their mean size, size distribution, and zeta potential; scanning electron microscopy and transmission electron microscopy for surface morphology; and differential scanning calorimetry analysis for confirmation of molecular dispersity of docetaxel in the nanoparticles. Nanoparticles were spherical with mean diameter below 200 nm, polydispersity of below 0.15, and positive zeta potential values. The entrapment efficiency of the nanoparticles was approximately 90%. In vitro release studies showed a sustained release characteristic for 10 days after a burst release at the beginning. Ex vivo studies showed a significant increase in the transportation of docetaxel from intestinal membrane of rat when formulated as nanoparticles. Cellular uptake of nanoparticles was investigated using fluoresceinamine-loaded nanoparticles. Docetaxel nanoparticles showed a high cytotoxicity effect in the Caco-2 and MCF-7 cell lines after 72 hours. It can be concluded that by combining the advantages of both thiolated polymers and colloidal particles, these nanoparticles can be proposed as a drug carrier system for mucosal delivery of hydrophobic drugs.

Fabrication of raspberry-like superhydrophobic hollow silica particles

Raspberry-like superhydrophobic hollow silica particles were prepared through a sacrificial polymer template method. The Stöber method was adopted to coat silica onto the surface of cationic polymethylmethacrylate(PMMA) particles by electrostatic interaction. The surface of the PMMA-silica composite particles exhibited raspberry-like morphology with high surface roughness. Hollow silica particles were then obtained by calcination to selectively remove the PMMA core. Subsequent modification with nonafluorohexyltriethoxysilane (NFH-silane) conferred superhydrophobicity on the hollow silica particles. The surface property of this particles were investigated by measuring their water contact angle, and the results showed that such perfluorinated raspberry-like hollow particles had unique superhydrophobic.

Design of photosensitive microstructured polymer optical fibers

We propose a new hole-assisted polymer optical fiber design to eliminate the influence of dopant diffusion and to increase the ultra violet (UV) writing efficiency in fiber Bragg grating inscription. The optical waveguide is formed inside a solid core polymethyl methacrylate (PMMA) doped with photosensitive trans-4-stilbenemethanol, surrounded by a ring of three large air holes with double cladding. We determined a map of the single-mode and multi-mode phase transitions using a finite-element-based vectorial optical mode solver. A wide range of geometrical configurations for the single-transverse-mode (HE11) propagation in the visible was obtained. The design is optimized to operate at the low optical loss wavelengths of 580 and 770 nm.

A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMAcore–shell fluorescent nanoparticles

A facile approach was developed to produce a dye-doped core–shell nanoparticle chemosensor for detectingCu2+ in aqueous media. The core–shell nanoparticle sensor was prepared by a one-step emulsifier-freepolymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino-5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilicpolyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethylmethacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic andbiocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity forCu2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding ofCu2+ ions. This makes the core–shell nanoparticle system a water-dispersible chemosensor forCu2+ ion detection. The quenching of fluorescence arises through intraparticleenergy transfer (FRET) from the dye in the hydrophobic PMMA core to theCu2+/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMAparticles with different diameters was determined, and it is found that the smallernanoparticle sample exhibits higher quenching efficiency, and the limit forCu2+ detectionis 1 µM for a nanoparticle sample with a diameter of∼30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigatedand the nanoparticle chemosensor displays high selectivity and antidisturbance for theCu2+ ion among the metalions examined (Na+, K+,Mg2+,Ca2+,Zn2+,Hg2+,Mn2+,Fe2+,Ni2+,Co2+ andPb2+). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may findapplications in cupric ion detection in the biological and environmental areas.

Charge controlling capability of ultra-thin shell layers formed on a spherical PMMA core particle surface

Core-shell (C-S) particles having ultra-thin shell layers on the core particle surface are prepared with the coacervation process and their surface structure or tribo-charging characteristics are investigated. Spherical, positively chargeable polymethyl-methacrylate (PMMA) particles having a particle size of approximately 10 μm are used as the core particles. Negatively or positively chargeable ultra-fine particles having a particle size of 3 to 100 nm are used as the shell particles. Through the coacervation process in water, the shell particles are precipitated onto the core particle surface to yield C-S particles. From SEM observation and the blow-off tribo-charge measurements of the CS particles, it is confirmed that (1) an ultra-thin single shell layer having a thickness of less than 20 nm and completely covering the underlying core surface is obtained, (2) the charging characteristics of the C-S particles are governed by the composition of the ultra-thin layer, (3) double shell C-S particles, in which a second ultra-thin shell layer is coated over the single shell C-S particles, are also obtained, (4) the charging characteristics of the double shell C-S particles are governed by the composition of the second ultra-thin shell layer.

Hollow carbon nanospheres prepared by carbonizing polymethylmethacrylate/polyacrylonitrile core/shell polymer particles

Hollow carbon nanospheres (HCNs) were synthesized by carbonizing fine core/shell particles of polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN). The PMMA/PAN core/shell particles were prepared using two-stage soapless emulsion polymerization. PMMA spheres with a diameter of approximately 200 nm were first synthesised by batch mode polymerization and then a PAN shell with a thickness of approximately 30 nm was polymerized on the surface of PMMA spheres by drop-wise addition of acrylonitrile monomer. After freeze drying, PMMA/PAN composite particles were stabilized in air at 250 °C and then carbonized in nitrogen at 1000 °C. Transmission electron microscopy of the final sample showed that all PMMA cores turned into pores and all PAN shells developed into carbon shells. The PMMA/PAN composite particles were converted to HCNs with some adhering with each other and some breaking of the carbon shells.

The damaging process in irradiated light guides and scintillating fibers

Different types of polymers – mainly fibers with polystyrene (PS) or polymethyl methacrylate (PMMA) core – were exposed to X-rays and γ rays, respectively. Optical transmission measurements and in addition electron spin resonance studies were performed. Shortlived absorption centers were detected in light guide fibers with PMMA or PS core. In both cases, they decayed within a few hours via a bimolecular process. In PMMA this absorption is due to peroxide radicals RO 2 which weakly absorb UV light ( λ⩽360 nm). The behaviour of PS is quite different. The observed shortlived absorption centers are not peroxide radicals, but it seems that the primary radicals (mainly benzyl radicals) survive for hours even in the presence of oxygen. The permanent induced absorption remaining after the end of the recovery process was measured as a function of dose (6–50 kGy). For wavelengths 400–500 nm it is a nonlinear function of dose.

Structure Formation of Blend and Sheath/Core Conjugated Fibers in High-Speed Spinning of PET, Including a Small Amount of PMMA

The blend of poly(ethylene terephthalate) (PET) and a small amount of polymer that has higher T g than PET, such as polymethylmethacrylate (PMMA)—and is dispersed finely as immiscible particles in PET—exhibits lower molecular orientation than pure PET under high-speed fiber spinning. To obtain insight into the mechanism of the lower molecular orientation of the blend fiber, the sheath/core structure of PET (sheath)/PMMA (core) conjugated fiber (the same PET/PMMA weight ratio as in the blend fiber), was produced as a model. The thinning profile of the fiber diameter along the spinning line and the birefringence distribution of the cross-section were examined and compared among pure PET fiber, the conjugated fiber, and the blend fiber. The conjugated fiber had the lowest molecular orientation of PET in the sheath part, and its thinning process was accelerated similar to the blend fiber. As a result of the distribution of molecular orientation across the diameter of the conjugated fiber, it is considered that PMMA, having the high T g , tends to solidify at a higher temperature (upstream) than PET in the thinning process, making the flow of PET accelerate as if it was pushed by PMMA. This causes the maximum dv/dx just before the solidification point to be smaller; therefore, the lower spinning stress, resulting in smaller birefringence of PET, can be considerable. This acceleration was generated at the interface of PET and PMMA, and spread toward the fiber surface as both polymers were thinning in elongational flow (in melt). On the other hand, close to the interface, molecules of PET were stretched by PMMA, resulting in an increase of birefringence. Such discussion is also considered to apply to the blend fiber. However, because the blend fiber had a significantly larger interface area compared with the conjugated fiber, it is considered that the increase of birefringence of PET by the interface drag force cannot be neglected. The larger particles of PMMA dispersed in PET results in the lower birefringence of PET that is supported by the elongation effect (i.e., the interface drag force).

The interfacial behavior of hard tissue replacement as revealed by SEM

INTRODUCTION:Hard Tissue Replacement (HTR) has been postulated to be an effective implant material for bone reconstruction and maintenance. HTR consists of a polymethylmethacrylate core coated with polyhydroxyethylmethacrylate and has been demonstrated in light microscopic studies to attach directly to bone. The present study was performed to add to the available information by investigating the interfacial bonding of this polymer using scanning electron microscopy.MATERIALS AND METHODS: Twenty Sprague-Dawley rats were anesthetized, a midline scalp incision was made to expose the calvaria and the periosteum reflected. Trephine defects were prepared by excising a 1 x 2-mm section of bone and the HTR polymer (24 mesh) inserted. The skin and periosteum were reapproximated and the incision closed. Pursuant to vascular perfusion with a mixture of aldehydes, the implants and surrounding tissue were extirpated in situ after 7-, 14-, 28-, and 56-day observation periods. Tissues were then washed in buffer, dehydrated, fractured in liquid nitrogen and dried in Freon. The samples were viewed in a JEOL JSM35CF SEM with x-ray energy dispersive analysis (EDXA).

光学用有機材料

Organic materials for optical use especially for optical fiber communication systems are described.Plastic optical fibers which are made through closed polymerization and fiber drawing apparatus are discussed. Deuterated poly-methyl methacrylate core optical fiber whose attenuation loss is 20 dB/km at 660 nm is explained.Light focusing plastic rods made by two step copolymerization technique or photo copolymerization technique are reviewed. Polymer optical waveguides such as dividers and star couplers using selective photo polymerization whose attenuation loss is 0.19 dB/cm at 0.83 μm are also described. Optical switches using liquid crystal as a cladding are explained and revealed to be effective to make 6 × 6 waveguide optical switches.Finally, nonlinear optical materials are described. Organic crystals such as p-nitro aniline are discussed and it is shown that hybridization with organic salts or inclusion complexes is effective to improve second order nonlinear optical effects.