Preparation and Alkylation of Carbon Nanofibers from Polymethyl Methacrylate

Carbon nanofibers have revolutionized nanotechnology due to their potential applications in emerging frontiers of research and industrial sectors. This can be attributed to their superior properties such as higher mechanical strength, unique surface characteristics, and improved adherence that is transmitted into the polymer matrix to form a nanocomposite with improved properties. Polymethyl methacrylate is a common carbon source for the synthesis of carbon nanofibres of its high mechanical strength, thermal stability, and low moisture and water absorbing capacity that allows its products to have several applications. In this work, we report the successful electrospinning of carbon nanofibres from Poly methyl methacrylate and functionalizing the resulting carbon nanofibres. The functionalized carbon nanofibres were analyzed to determine their solubility/dispersion in selected organic solvents, then characterized using Fourier transform infra-red spectroscopy, Raman spectroscopy, scanning electron microscopy combined with Energy dispersive spectroscopy and Thermalgravimetric analysis.

Injectable bioactive polymethyl methacrylate-hydrogel hybrid bone cement loaded with BMP-2 to improve osteogenesis for percutaneous vertebroplasty and kyphoplasty

Poly methyl methacrylate(PMMA)bone cement is used in augmenting and stabilizing fractured vertebral bodies through percutaneous vertebroplasty(PVP)and percutaneous kyphoplasty(PKP).However,applications of PMMA bone cement are limited by the high elasticity modulus of PMMA,its low biodegradability,and its limited ability to regenerate bone.To improve PMMA bio activity and biodegradability and to modify its elasticity modulus,we mixed PMMA bone cement with oxidized hyaluronic acid and carboxymethyl chitosan in situ cross-linking hydrogel loaded with bone morphogenetic protein-2(BMP-2)to achieve novel hybrid cement.These fabric ated PMMA-hydrogel hybrid cements exhibited lower setting temperatures,a lower elasticity modulus,and better biodegradability and biocompatibility than that of pure PMMA cement,while retaining acceptable setting times,mechanical strength,and inj ectability.In addition,we detected release of BMP-2 from the PMMA-hydrogel hybrid cements,significantly enhancing in vitro osteogenesis of bone marrow mesenchymal stem cells by up-regulating the gene expression of Runx2,Coll,and OPN.Use of PMMA-hydrogel hybrid cements loaded with BMP-2 on rabbit femoral condyle bone-defect models revealed their biodegradability and enhanced bone formation.Our study demonstrated the favorable mechanical properties,biocompatibility,and biodegradability of fabricated PMMA-hydrogel hybrid cements loaded with BMP-2,as well as their ability to improve osteogenesis,making them a promising material for use in PKP and PVP.

Biodegradation behavior of polymethyl methacrylate−bioactive glass 45S5 composite coated magnesium in simulated body fluid

The biodegradation behavior of Mg,coated by polymethyl methacrylate as well as polymethyl methacrylate(PMMA)−bioactive glass(BG)composite was investigated.Electrophoretic deposition and dip coating techniques were adopted to prepare composite coating using a suspension of different percentages of the above two chemical materials.The deposited coatings were characterized using SEM,EDS,FTIR,and water contact angle measurements.Biodegradation behavior study of the coated Mg was performed using linear polarization,impedance spectroscopy,and immersion tests in simulated body fluid.The compact and homogeneous composite coating was developed as evidenced by electron microscopy results.The water contact angle measurement showed a 44°increase in the contact angle of the composite coated Mg compared to the uncoated one.The composite coating was covered by a bone-like hydroxyapatite layer after 336 h,indicating that the coating has an excellent in vitro bioactivity.The electrochemical testing results confirmed a significant reduction,96.9%,in the biodegradation rate of Mg coated with the composite prepared from 45 g/L PMMA+3.5 g/L 45S5 GB suspension compared to that of the uncoated one.Therefore,the composite coated Mg can be proposed as a promising material for biodegradable implant application.

Measurement of Secondary Electron Energy Spectra of Polymethyl Methacrylate

We report on a novel and convenient method of measuring secondary electron spectra for insulators in a secondary electron yield measurement system with a planar grid analyzer configuration and a metal mesh probe. In this measurement, the planar grid is negatively biased to force some emitted secondary electrons to return to the sample surface and to neutralize charges accumulated on the sample during the previous beam irradiation. The surface potential of the sample is then measured by use of a metal mesh probe. The grid bias for neutralization corresponding to the zero surface potential is determined based on the linear relationship between the surface potential and the grid bias. Once the surface potential equals zero, the secondary electron spectra of polymethyl methacrylate（PMMA） are studied experimentally by measuring the -curve and then fitting it to Everhart＇s formula. The measurement results show that the peak energy and the full width at half maximum of the spectra are 4.26 eV and 14.06 eV, respectively.

A Novel Method for Preparing Approximately Micron-sized Polymethyl Methacrylate Microspheres with Clear Surface

Polymethyl methacrylate (PMMA) microspheres with clear surface and diameter close to 1 祄 were synthesized by newly soap-free emulsion polymerization. The results showed that the presence of ethanol and NaCl made the increase of diameter and distribution, while the presence of toluene could avoid the problem of the increase of distribution, resulting a harvest of PMMA microspheres with a diameter close to 1 祄.

Preparation and Fluorescence Properties of Polymethyl Methacrylate Resin Incorporated with Sodium Tris (Pyridine Dicarboxylato) Europate

Based on the strong fluorescence and the highly thermal stability of sodium tris (pyridine dicarboxylato) europate (Na 3Eu(DPA) 3), polymethyl methacrylate (PMMA) composite material incorporated with the complex, PMMA: Na 3Eu(DPA) 3, was prepared at 250 ℃. The fluorescence behavior of PMMA: Na 3Eu(DPA) 3 material was examined. The results show that the composite material keeps the luminescent characteristics of the Eu 3+ chelate after PMMA is incorporated with Na 3Eu(DPA) 3, and strong orange-red emission of the composite was observed. The fluorescence intensity of the composite material increases with the increase of the weight ratio of Na 3Eu(DPA) 3 to PMMA, but the relationship is not linear.

A Novel Polymethyl Methacrylate (PMMA)-TiO_2 Nanocomposite and Its Thermal and Photic Stability

A new kind of polymethyl methacrylate （PMMA）-TiO2 nanocomposite was synthesized through polymerization. The thermal and photic stability of this PMMA TiO2 nanocomposites were investigated. The as prepared samples were characterized by scanning electron microscopy （SEM）, UV-Vis spectroscopy, differential thermal analysis （DTA） and the photo-induced weight loss, The results show that the photostability of the PMMA-TiO2 nanocomposite is higher than that of the pure PMMA under UV-light irradiation, The weight loss of the pure PMMA reaches 30 % after 300 h UVirradiation, while the composite only 0.3% under the identical experimental condition. The glass transition temperature （TR） of pure PMMA is only 80℃, while the Tg of the composite reaches 258℃. Compared with pure PMMA, the thermal stability of the composite is greatly enhanced.

Effect of local massage on prevention and treatment of intra-arterial polymethyl methacrylate embolism complications:An experimental animal study

Background:Massage is generally believed to be a simple and effective method for preventing necrosis when intravascular injection emboli are suspected.Due to its good dispersive properties,polymethyl methacrylate(PMMA)was used as the test filler.The main purpose of this study was to observe whether local massage as a simple remedial measure can promote the diffusion of filler and reduce the necrosis rate for intra-arterial embolism.Methods:Rabbit ears with the central ear artery(CEA)main trunk totally or segmentally obstructed 5 min after PMMA injection were studied.In order to simulate the massage effect of the fingers,the massage group was treated with a small beauty massage bar with a fixed vibration frequency along the direction of the blood flow.CEA blood flow and skin lesions were also analyzed.Results:The baseline data were similar between the control and massage groups.Compared to the control group,the recanalization rate of the CEA trunk in the treatment group increased significantly after massage.However,there was no significant difference in the visible rate of transparent embolus on the 1st day after treatment,nor in the necrosis degree or area of soft tissue damage on the 7th day after treatment.Further analysis showed that massage tended to have a positive effect on segmentally obstructed cases at 5 min after injection but a negative effect on totally obstructed ears at 5 min.Conclusion:Local massage cannot reduce the complications of tissue necrosis after intra-arterial PMMA injection.Prevention is key to reducing complications.

Force-Induced Enhancement of Hydrophilicity of Individual Polymethyl Methacrylate Chain

Comprehensive Summary,Polymethyl methacrylate(PMMA)has been widely applied in diverse fields such as medicine and engineering materials due to its good hydrophilicity and biocompatibility.However,another term for PMMA,Plexiglas,means that it is water insoluble.These features of PMMA are valuable but seem paradoxical.To explore the underlying mechanism of the paradoxical properties,the interactions between PMMA and water have been investigated by atomic force microscopy(AFM)-based single-molecule force spectroscopy(SMFS).The single-chain elasticity of PMMA obtained in aqueous solutions is significantly different from that obtained in non-aqueous environments,implying that PMMA can form hydrogen bonds with water molecules.

Optical properties and Judd-Ofelt analysis of Nd2O3 nanocrystals embedded in polymethyl methacrylate

PMMA matrices were doped with nano-crystalline neodymium oxides synthesized by thermal decomposition process. X-ray diffraction and high-resolution transmission electron microscopy measurements were carried out to investigate the structure, phase, and the morphology of the Nd_2O_3 nanocrystals and those embedded in the PMMA matrix. The average grain sizes were estimated 35 ± 6 nm and 46 ± 4 nm for non-annealed and annealed Nd_2O_3 particles, respectively. The grain size distributions（GSD） were calculated from the diffraction peaks of the annealed and non-annealed Nd_2O_3 powders and doped PMMA samples. The mass density, refractive index. UV-Visible absorption spectra were measured and the data were analyzed using the Judd-Ofelt approach to determine the oscillator strengths, the spontaneous emission probabilities and the branching ratios as a function of the nano-crystalline Nd_2O_3 content in the range of 0.1 wt.%-20 wt.% of MMA. Luminescence spectra upon 808 nm diode laser excitation were carried out in the wavelength range of 850-1550 nm at room temperature. The photoluminescence study has shown that the reasonably sharp emission peaks were observed upon heat treatment at 800 ℃ for 24 h for all concentrations of Nd_2O_3 nanopowders in PMMA. The infrared laser transition of Nd^（3＋） ions at about 1.06 μm due to the ~4F_（3/2）→~4I_（11/2） transition was analyzed and discussed in Nd_2O_3 system for their possible applications in the photonic technology.

Effects of self-blood on the molding process of polymethyl methacrylate bone cement

Objective：To evaluate whether the self-blood has influence on the molding process of polymethyl methacrylate （PMMA） bone cement,and to make sure whether it is valuable for the clinical practice.Methods：An in vitro study was performed to evaluate the prolonging-effect of self-blood on PMMA bone cement.The effect of prolonging was evaluated by the dough time （TD） and operable time （To）.Moreover,hardness test,squeezing value test and peak temperature test were also conducted to complete the evaluation of this program.Results：The self-blood,especially the plasma,could greatly prolong the handling time of PMMA bone cement without affecting its basic characteristics including hardness,leakage level and peak temperature.On the other hand,we found that in some abnormal conditions,for example with hyperlipemia,self-blood though can also prolong the handling time,would cause some sideeffects.Conclusion：We report a new effective way to prolong the handling time of PMMA bone cement by adding moderate amount of self-blood.But “individualized medicine” should be noticed because some abnormal conditions like hyperlipemia would cause undesired side-effects.

Novel reparation method for polymethyl methacrylate optical windows of aircrafts damaged by service environment

The optical properties of polymethyl methacrylate(PMMA)with varying degrees of artificial scratches have been studied with the aim of reproducing the change of visibility of an aircraft’s PMMA optical windows after being damaged in their service environment.A novel maintenance method that can perfectly restore the optical property of PMMA has been identified and employed in the repair of the scratches that are formed on the surface of PMMA.This convenient and low-cost method entails polishing PMMA with different types of sandpaper to remove the scratches,and then spin-coating the repair solution in order to restore the optical properties of PMMA.The effect of this repair mechanism and parameters of the repair process were studied.The results indicated that the optical performance of PMMA is closely related to the mesh size of sandpaper,and improper parameter selection destroys the general effect of the repair.When the number of sandpaper mesh is low,the size of the abrasive particle is relatively larger,which can cause deeper friction marks on the surface of PMMA optical windows.Surface treatment using 5000 mesh sandpaper lowers surface roughness(R——a=0.566 nm),and optical transmittance in visible range can be restored to more than 88%.

Polymethyl Methacrylate-Collagen-Magnesium Hydroxyapatite Bone Cement Preparation for Orthopedic Application

In this research,bone cement was prepared by mixing 2 g of magnesium hydroxyapatite(laboratory synthesized),12 g of polymethyl methacrylate,4 g of methyl methacrylate,and collagen(1,3,and 6 g).The samples were molded in a circular shape.They were inspected by visual microscopy,FTIR,XRD,and FESEM.They were engrossed in synthesized simulated body fluid for 1 month and then inspected by visual microscopy,FTIR,XRD,and FESEM.The samples prepared from 6 g of collagen showed the highest hydroxyapatite formation(high osseointegration)than the other samples.

AN EPOXY/(METHYL METHACRYLATE)INTERPENETRATING POLYMER NETWORK FOR NONLINEAR OPTICS

An interpenetrating polymer networks (IPN) consisting of an epoxy-based polymer network and a polymethyl methacrylate network were synthesized and characterized. The IPN showed only one T-g, and hence a homogeneous-phase morphology was suggested. The second-order nonlinear optical coefficient (d(33)) of the IPN was measured to be 1.72 X 10(-7) esu. The study of NLO temporal stability at room temperature and elevated temperature (100 degrees C) indicated that the IPN exhibits a high stability in the dipole orientation due to the permanent entanglements of two component networks in the IPN system. Long-term stability of second harmonic coefficients was observed at room temperature for more than 1000 h.

STUDY ON FLUORESCENCE BEHAVIOUR OF EU^(3+) CONTAINING POLY(METHYL METHACRYLATE)

Fluorimetry has been used to characterize ionomers synthesized by copolymerization ofmethyl mehacrylate, methacrylic acid and europium methacrylate (EMA). Under excita-tion of UV light at 375 nm no seif-quenching was found in fluorescence of EMA containingionomers at 615nm within the concentration range of 1.6×10^(-2) to 11.49×10^(-2) mol%.This means that the distance between two Eu^(3+) ions is larger than 5nm. In the sameconcentration range seif-quenching took place in europium octanoate (EOA) containingpoly(methyl methacrylate) in which EOA was doped as an additive.

Influences of IL-6R Antibody on PMMA Bone Cement-mediated Expression of OPG and RANKL in Synovial Fibroblasts

Effect of interleukin-6 receptor （IL-6R） antibody on polymethyl methacrylate （PMMA） bone cement-mediated expression of osteoprotegerin （OPG） and ：receptor activator of nuclear fac- tor-kappaB ligand （RANKL） in synovial fibroblasts was investigated. Synovial tissue obtained from to- tal knee arthroplasty was digested and cultured. Inverted microscope was employed to observe the synovial cells and immunocytochemistry （SABC method） staining was used to identify synovial fibro- blasts. This experiment was divided into three groups according to different culture media： PMMA group （75μg/mL PMMA bone cement particles）, IL-6R antibody group （10 ng/mL IL-6R antibody＋75 μg/mL PMMA bone cement particles）, and control group （no IL-6R antibody or PMMA bone cement particles）. Influence of IL-6R antibody and PMMA on proliferation of synovial fibroblasts was meas- ured by cell counting kit-8 （CCK-8）. ELISA method was used to measure OPG and RANKL levels in culture solution. Fluorescence quantitative real-time PCR （FQ-PCR） was used to detect the expression of OPG and RANKL mRNA. After three consecutive passages, more than 95% of the primary synovial cells became long spindle fibroblast-like cells. SABC staining results showed that the fibroblast-like cells were negative for anti-CD68 antibody and positive for anti-vimentin antibody, with brown madder stained. CCK-8 test demonstrated that the absorbance （A） value at 450 nm was significantly lower in IL-6R antibody group than in PMMA group and control group （P〈0.01）, but there was no statistically significant difference in A value at 450 nm between the control group and PMMA group （P〉0.05）. Re- suits of ELISA indicated that the expression of OPG was significantly higher in IL-6R antibody group than in PMMA group and control group （P〈0.01）. The expression of RANKL was inhibited （P〈0.05）, and the ratio of OPG/RANKL was significantly increased in IL-6R antibody group as compared with PMMA group and control group. There was no significant difference in the expression of OPG between control group and PMMA group （P〉0.05）, but the expression of RANKL was higher in PMMA group than in control group （P〈0.05）, and there was a significant difference in the ratio of OPG/RANKL be- tween them （P〈0.05）. Results of FQ-PCR revealed the expression of RANKL mRNA was significantly inhibited （P〈0.01） and the expression of OPG mRNA was significantly increased （P〈0.01） in IL-6R an- tibody group as compared with PMMA group and control group. The expression of RANKL mRNA was higher in PMMA group than in control group （P〈0.05）, but the expression of OPG mRNA had no sig- nificant difference between them （P〉0.05）. IL-6R antibody could significantly increase the expression of OPC~ but inhibit the expression of RANKL, which might provide a theoretical basis of molecular bi- ology for the prevention and treatment of aseptic loosening of prosthesis.

Residual stress measurement for injection molded components

Residual stress induced during manufacturing of injection molded components such as polymethyl methacrylate （PMMA） affects the mechanical and optical properties of these components. These residual stresses can be visualized and quantified by measuring their birefringence. In this paper, a low birefringence polariscope （LBP） is used to measure the whole-field residual stress distribution of these injection molded specimens. Detailed analytical and experimental study is conducted to quantify the residual stress measurement in these materials. A commercial birefringence measurement system was used to validate the results obtained to our measurement system. This study can help in material diagnosis for quality and manufacturing purpose and be useful for understanding of residual stress in imaging or other anolications.

Spherical Micro-lens Array of PMMA Produced by Micro-molding

Micro-lens （ML） and Micro-lens array （MLA） are important optical components widely used in many fields; Soft-lithography, a vital little process technology, has its unique performance to produce ML and MLA; The cylinder and spherical MLA of polymethyl methacrylate （PMMA） were successfully obtained by micromolding inSoft-lithography. Some suitable experimental parameters in the process were discussed, and the imaging property of the MLA was also studied simply.

Fabrication and Characterization of PMMA/MWCNTs Composite Materials

In order to improve the mechanical properties and thermal conductivity of polymethyl methacrylate(PMMA),multi-walled carbon nanotubes(MWCNTs)were used as reinforcement through in situ polymerization method to prepare PMMA/MWCNTs composites by changing the reaction time,polymerization temperature and the content of MWCNTs.The effects of different reaction conditions on the properties of the composites were studied.The results show that the mechanical properties,thermal/electrical conductivity and thermal stability of the composites are improved compared with the PMMA matrix.The tensile strength of the composites is increased by up to 24%.The bending strength of the composite material increases from20.41 to 68.04 MPa,and the maximum increase is 233%.Meanwhile,when the content of MWCNTs is 3 wt%,the thermal conductivity of the composite is 0.335 W/(m·K),which increases by138%,and the electrical conductivity is 3.94 S/m.The thermal stability of the composite has been significantly enhanced.The modified PMMA will be widely used in medicine,communications,electronics and other fields.

A Study on the Preparation PMMA of Ultrafines

Polymethylmethacrylate (PMMA) cltrafines have been prepared applying the meth- od of emulsion dispersion. Their sizes aie determined by size analysis apparatus SA-CP3. Factors affecting particle diameter and its distribution, which include PMMA conoentration, pH value and water amount, were discussed by a series of comparaison experiments. The influential principle was found, PMMA ultafines having a median diameter of 5.71μm were obtained, the ratio of the particles whose median diameters are under 10μm is 65.%. This method can be applied to the preparation of other oil-soluble polymer ultrafines, it has the advantages of simple, quick and easy to be controlled. It is possible to make it in- dustrialized in the future.