Methyl Methyacrylate Research Articles

Characterization and evaluation of a novel silver nanoparticles-loaded polymethyl methacrylate denture base: In vitro and in vivo animal study.

The aim of this study was to optimize the preparation method of polymethyl methacrylate (PMMA) denture base loaded with nano silver (NAg), to more effectively and safely impart sustainable antibacterial functions. NAg solution was synthetized and mixed with acrylic acid and methyl methyacrylate (MMA) monomer in order to prepare a new type of NAg solution (NS)/polymer methyl methacrylate denture base specimens (NS/PMMA). The surface morphology, mechanical strength, antimicrobial activity, anti-aging performance, cytotoxicity and biocompatibility of NS/PMMA denture base were evaluated in comparison with specimens fabricated using traditional NAg adding methods and NAg-free denture base. The aesthetic characteristics and mechanical strength of NS/PMMA denture base met the clinical application requirements. Meanwhile, NS/PMMA denture base showed better antibacterial activity, anti-aging properties, no cytotoxicity and displayed exceptional biocompatibility. NS/PMMA denture base thus has great potential for clinical application.

In Situ Dendritic Cell Vaccine for Effective Cancer Immunotherapy

A cancer vaccine is an important form of immunotherapy. Given their effectiveness for antigen processing and presentation, dendritic cells (DCs) have been exploited in the development of a therapeutic vaccine. Herein, a versatile polymersomal nanoformulation that enables generation of tumor-associated antigens (TAAs) and simultaneously serves as adjuvant for an in situ DC vaccine is reported. The chimeric cross-linked polymersome (CCPS) is acquired from self-assembly of a triblock copolymer, polyethylene glycol-poly(methyl methyacrylate- co-2-amino ethyl methacrylate (thiol/amine))-poly 2-(dimethylamino)ethyl methacrylate (PEG-P(MMA- co-AEMA (SH/NH2)-PDMA). CCPS can encapsulate low-dose doxorubicin hydrochloride (DOX) to induce immunogenic cell death (ICD) and 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH), a photosensitizer to facilitate photodynamic therapy (PDT) for reactive oxygen species (ROS) generation. This combination is able to enhance the population of TAAs and DC recruitment, eliciting an immune response cascade. In addition, CCPS with primary and tertiary amines act as adjuvant, both of which can stimulate DCs recruited to form an in situ DC vaccine after combination with TAAs for MC38 colorectal cancer treatment. In vivo results indicate that the all-in-one polymersomal nanoformulation (CCPS/HPPH/DOX) increases mature DCs in tumor-draining lymph nodes (tdLNs) and CD8+ T cells in tumor tissues to inhibit primary and distant MC38 tumor growth following a single intravenous injection with a low dose of DOX and HPPH.

Monitoring PMMA Elimination by Reactive Ion Etching from a Lamellar PS-b-PMMA Thin Film by ex Situ TEM Methods

Block copolymer thin films require selective elimination of one of their constituent blocks to access their potential as lithographic nanopatterns. This paper demonstrates an on-substrate TEM-based approach for establishing the removal of poly(methyl methyacrylate) from vertically oriented lamellar polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) thin films and subsequent transfer to the underlying silicon by reactive ion etching. The ex situ microscopy technique presents an insight into the removal of PMMA, the etch end point, PS faceting, etch anisotropy, and residual PS thickness.

Determination of Zonal Boundaries in Articular Cartilage Using Infrared Dichroism

To determine the sub-tissue structural zonal boundaries in articular cartilage, a novel infrared (IR) microscopic imaging method based on the dichroic nature of the amide components has been developed and is discussed in this article. Thin canine cartilage-bone sections embedded in paraffin as well as in poly(methyl methyacrylate) (PMMA) were imaged under two orthogonal polarization states at 6.25 mum pixel size. The depth-dependent anisotropy of the amide components at perpendicular polarization states attributed by the collagen constituent in cartilage was analyzed. Since the transitional zone fibers are randomly arranged and the dichroic ratio value reaches unity in this zone, it is possible to identify the transitional zone boundaries, thus dividing the whole-depth tissue into three structural zones (superficial, transitional and radial). The zone division results from the infrared method agree well with the results from the established polarized light microscopy (PLM) method, which promises the potential of infrared imaging as an independent technique for the zonal boundary determination. The advantages of this dichroic ratio method are (1) it is independent of mode of operation (transmission/reflection), (2) it is independent of sample thickness, (3) either a polarizer or an analyzer can be used in experiments to determine zonal boundaries, and (4) it is sample orientation independent.

Synthesis and Characterization of 3,5‐Dimethoxyphenyl Methacrylate and Methyl Methyacrylate Copolymers: Determination of Monomer Reactivity Ratios

A new monomer, 3,5‐dimethoxyphenyl methacrylate (DMOPM) has been synthesized from the precursor viz.,3,5‐dimethoxy phenol. Copolymerization of DMOPM with methyl methacrylate (MMA) has been carried out in ethyl methyl ketone (EMK) by free radical solution polymerization at 70±1°C utilizing benzoyl peroxide (BPO) as initiator. Poly(DMOPM‐co‐MMA) copolymers were characterized by 1H‐NMR,13C‐NMR, and the copolymer compositions were evaluated by 1H‐NMR spectroscopy. The monomer reactivity ratios were estimated using Fineman‐Ross, Kelen‐Tudos and extended Kelen‐Tudos methods. The solubility was tested in various polar and non polar solvents. The molecular weight and polydispersity indices of the copolymers were determined by using gel permeation chromatography. By TGA and DSC analyses, the thermal properties of the polymers have been studied.

Synthesis and surface characterization of poly(methyl methacrylate)-block-polydimethylsiloxane copolymers from macroazoinitiator

Poly(methyl methyacrylate)-block-polydimethylsiloxane (PMMA-b-PDMS) copolymers with various compositions were synthesized with PDMS-containing macroazoinitiator (MAI), which was first prepared by a facile one-step method in our lab. Results from the characterizations of X-ray photoelectron spectroscopy (XPS), contact angle measurements, and atomic force microscopy (AFM) showed that the copolymer films took on a gradient of composition and more PDMS segments enriched at the film surfaces, which then resulted in the low surface free energy and little microphase separation at the film surfaces. By contrast, transmission electron microscopy (TEM) analysis demonstrated that distinct microphase separation occurred in bulk. Slight crosslinking of the block copolymers led to much steady morphology and more distinct microphase separation, in particularly for copolymers with low content of PDMS. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Efficient gene delivery using a novel core‐shell nanoparticle and HMGB1 system

We have recently developed a highly efficient gene delivery system of amphiphilic core-shell nanoparticle composed of poly(methyl methyacrylate) core and branched poly(ethylenimine) shell for transfection of DNA into mammalian cells. In order to enhance the efficiency and to provide the nuclear targeting capability, we have tried the inclusion of a nuclear protein HMGB1 in our system. The high mobility group protein HMGB1 itself has been shown in various earlier studies to be able to enhance the transfection efficiency when used with both naked DNA and liposomes. In our present study, HMGB1 protein was added together with the DNA and the nanoparticles to form the gene delivery complexes. Formation of the complexes was demonstrated using agarose gel retardation assay and the DNA with HMGB1 still bound can be released from the complexes with the use of polyaspartic acids. When used in transfection into mammalian cells, transfection efficiency of the HMGB1-nanoparticle-DNA complexes was found to be significantly higher than that without HMGB1. We believe that this system with the inclusion of HMGB1 has the potential to be developed into a viable and efficient non-viral gene carrier for use in vivo. YSS is supported by a PolyU studentship, KLDL is supported by a PolyU internal research grant and PL is supported by a CERG grant.

Preparation and properties of core [poly(styrene‐n‐butyl acrylate)]–shell [poly(styrene–methyl methacrylate–vinyl triethoxide silane)] structured latex particles with self‐crosslinking characteristics

AbstractStructured latex particles with a slightly crosslinked poly(styrene‐n‐butyl acrylate) (PSB) core and a poly(styrene–methacrylate–vinyl triethoxide silane) (PSMV) shell were prepared by seed emulsion polymerization, and the latex particle structures were investigated with Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, transmission electron microscopy, and dynamic light scattering. The films that were formed from the structured core (PSB)–shell (PSMV) particles under ambient conditions had good water repellency and good tensile strength in comparison with films from structured core (PSB)–shell [poly(styrene–methyl methyacrylate)] latex particles; this was attributed to the self‐crosslinking of CH2CHSi(OCH2CH3)3 in the outer shell structure. The relationship between the particle structure and the film properties was also investigated in this work. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1824–1830, 2006

Morphology and mechanical properties of urethane acrylate resin networks

A series of urethane acrylate resins (UARs) having various amounts of hard segment were synthesized from poly(oxypropylene) diols (PPOs) with different molecular weights and characterized. The relationship between the morphologies and mechanical properties of these UAR (UARX-Y-Z, in which X means the molecular weight of PPO, Y means the content of hard segment, and Z means the content of comonomer) networks was investigated in detail. It was found that the morphology of the UARX-Y-Z network was related to the contents of hard segment and the comonomer (methyl methyacrylate—MMA) as well as the molecular weight of PPOs. The UAR1000-0-34 network synthesized from PPO210(Mn = 1000) is a homogeneous system due to the good compatibility between the PPO210 and the MMA segment. TheUAR1000-0-60 network exhibits the morphology of partial microphase separation resulting from increasing the length of the MMA segment, so as to decrease the miscibility between the soft and hard segment. For the UAR1000-30-34 network having a higher content of the hard segment, the hard segments tend to form domains with the limited short-range and long-range order, leading to the formation of the microcrystallites, and therefore it shows higher tensile strength and elastic modulus. For UAR400-0-34 network with lower molecular weight PPO204 (Mn=400), a high glass transition temperature and some microcrystallites were observed. Such a network exhibits the best mechanical properties over all UAR networks studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1532–1537, 2000

Morphology and mechanical properties of urethane acrylate resin networks

A series of urethane acrylate resins (UARs) having various amounts of hard segment were synthesized from poly(oxypropylene) diols (PPOs) with different molecular weights and characterized. The relationship between the morphologies and mechanical properties of these UAR (UARX-Y-Z, in which X means the molecular weight of PPO, Y means the content of hard segment, and Z means the content of comonomer) networks was investigated in detail. It was found that the morphology of the UARX-Y-Z network was related to the contents of hard segment and the comonomer (methyl methyacrylate—MMA) as well as the molecular weight of PPOs. The UAR1000-0-34 network synthesized from PPO210(Mn = 1000) is a homogeneous system due to the good compatibility between the PPO210 and the MMA segment. TheUAR1000-0-60 network exhibits the morphology of partial microphase separation resulting from increasing the length of the MMA segment, so as to decrease the miscibility between the soft and hard segment. For the UAR1000-30-34 network having a higher content of the hard segment, the hard segments tend to form domains with the limited short-range and long-range order, leading to the formation of the microcrystallites, and therefore it shows higher tensile strength and elastic modulus. For UAR400-0-34 network with lower molecular weight PPO204 (Mn=400), a high glass transition temperature and some microcrystallites were observed. Such a network exhibits the best mechanical properties over all UAR networks studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1532–1537, 2000

Interpenetrating polymer networks of epoxy resin and urethane acrylate resin: 2. Morphology and mechanical property

A new kind of simultaneous interpenetrating polymer networks (SINs) composed of epoxy resin (epoxy) and urethane acrylate resin (UAR) having various amounts of hard segment and prepared with poly(oxypropylene) polyol (PPO) having different molecular weights was synthesized and the relationship between the morphologies and mechanical properties of these SINs was investigated in detail. It was found that the different morphologies of these SINs were related to various structures of UAR network. The morphology of such SINs not only depends on the compatibility between the poly(methyl methyacrylate) segments existing in UAR network and epoxy network, but is related to the microphase separation of UAR network as well. The experimental data showed that the epoxy network could be toughened obviously by UAR network synthesized with PPO having low molecular weight ( Mn=400), i.e., the impact strength increased appreciably and the tensile strength was very close to that of pure epoxy network for the SIN material. Furthermore, the UAR network was greatly reinforced by epoxy network, although the phase separation morphology was observed in these SINs synthesized.

Supercritical carbon dioxide assisted blending of polystyrene and poly(methyl methyacrylate)

AbstractA method for blending polystyrene and poly(methyl methacrylate), (PMMA), with the addition of supercritical carbon dioxide has been investigated. The first series of blends was a PMMA and polystyrene with similar melt viscosities. The second series of blends was a PMMA and polystyrene with a viscosity ratio (ηPMMA/ηpolystyrene) of about 20. The results show that a reduction in the size of the minor or dispersed phase is achieved when supercritical carbon dioxide is added to the blend system. A high‐pressure mixing vessel was used to prepare the blends under pressure with carbon dioxide for batch blending. The solubilities of CO2 in PMMA and polystyrene, measured in the high‐pressure mixing vessel at 200°C and 13.78 MPa (2000 psi) was 5.8 and 3.6 wt%, respectively. A single screw extruder was used to study the effects of carbon dioxide on the viscosity of polymer melts. The melt viscosity of PMMA was reduced by up to 70% with approximately 0.4 wt% CO2. The melt viscosity of polystyrene was reduced by up to 56% with a CO2 content of 0.3 wt%. A twin screw extruder was used to study the effects of injecting carbon dioxide in a continuous compounding operation.

Microfabricated Centrifugal Microfluidic Systems: Characterization and Multiple Enzymatic Assays

This paper describes a microfluidic system in which fluids are pumped by centrifugal force through microscopic channels defined in a plastic disk in order to perform complex analytical processes. The channels are created either by casting poly(dimethylsiloxane) against molds fabricated by photolithography or by conventional machining of poly(methyl methyacrylate). The channels have a wide range of diameters (5 μm−0.5 mm) and depths (16 μm−3 mm). Fluids are loaded into reservoirs near the center of the disk, the disk is rotated on the shaft of a simple motor at 60−3000 rpm, and the fluids are pumped outward by centrifugal force through microfluidic networks. The control of flow in the time domain, i.e., gating, is achieved by the use of passive valves based on capillary forces. Flow rates ranging from 5 nL/s to >0.1 mL/s have been achieved using channels of different dimensions and different rates of rotation. The method of pumping is insensitive to many physicochemical properties of the liquid, such as pH and ionic strength, so it has been possible to pump biological fluids, such as blood and urine, a buffer containing a detergent, and some organic solvents. A system that performs multiple (48) enzymatic assays simultaneously using colorimetric detection on a dedicated instrument has been demonstrated. These integrated assays have been used both to yield the Michaelis constant (Km) of an enzyme and to determine the dose response of an enzyme to a drug. The fluid pumping and control embodied in this system may be readily integrated with other analytical components (e.g., heating, detection, and informatics) to form the basis for a microscale total analysis system for use in genomics, proteomics, high-throughput screening, and molecular diagnostics.

Study of poly(methyl methacrylate) thin films doped with laser dyes

1,1,4,4-tetraphenyl-1,3-butadiene, Coumarin-334 and rhodamine 6G have been used to form single, binary and ternary dye-doped poly(methyl methyacrylate) thin films by the dip-coating method. The thickness of the films was controlled by adjusting the polymer concentration. The photophysical properties of the dyes in solution and in film have been investigated by steady-state and time-resolved fluorescence spectroscopy. Excited-state resonance energy transfer between these dyes has been observed leading to a very broad color emission by the ternary system when excited with ultraviolet light. Laser excitation led to radiation enhancement by waveguide gain and to extensive spectral narrowing.

Bamboo-Plastic Composite with MMA

Abstract Bamboo-plastic composite (BPC) was prepared under Co-60 gamma radiation with Talla bamboo of Bangladesh using methyl methyacrylate (MMA) as the bulk monomer combined with methanol at different proportions. Skin, and middle and inner portions of bamboo were longitudinally separated and were used for making the BPC. The polymer loading increased very slightly and the tensile strength (TS) of the composite was enhanced by 9%–12%. However, incorporation of some additives such as NVP, TPGDA, TMPTA, LiNO3, and urea to the bulk monomer enhanced the TS values further. Lithium yielded the highest TS values, increased by 43%, and bending strength (BS), increased by 59%. When urea was mixed with lithium, the corresponding TS value increased to 48% with the middle part of the bamboo. Water absorption was low with BPC compared to the untreated bamboo.

Experimental and theoretical analysis of both the small- and the large-stress mechanical response of poly(methyl methacrylate)

Abstract The results of both dynamic mechanical and large-stress plastic deformation experiments performed on poly(methyl methyacrylate) below and through its glass transition temperature are presented. The observed behaviours are successfully compared with the predictions of a molecular theory by Mangion, Cavaillé and Perez, that allows the description of both the low-stress dynamic mechanical response and the large-stress plastic deformation behaviour of amorphous polymers, based on a unique set of equations.

Viscometric study of aggregation phenomena in polymer dilute solutions and determination of the critical concentration [formula omitted

A crossover is observed in the variation of the reduced viscosity, η sp c , as a function of the concentration, c, for the systems poly(methyl methyacrylate)/nitromethane and poly(vinyl-2 pyridine)/benzene. This crossover is correlated with the critical concentration of the polymer c∗∗ in which the macromolecular coils start their contacts. The critical concentration c∗∗ is related with the molecular weight and the intrinsic viscosity of the polymer through the scaling laws: c∗∗∝ M −α and c∗∗∝[η] −1 .

PMMA electron resists with narrow molecular weight distribution

Narrow molecular weight distribution (M̄w/M̄n<1.1) poly (methyl methyacrylate) [PMMA] with low molecular weight (M̄w<200 000) has been evaluated as an electron resist. It is shown that sensitivity and contrast of these narrow distribution resists can be altered by prebaking either above or below the glass transition temperature. Sensitivity of narrow distribution PMMA resists prebaked below the glass transition temperature (Tg) can be a factor of 5 greater than the same resist prebaked above Tg . Sensitivity improvement is shown to be caused by solvent trapped in the network of narrow distribution resists prebaked below Tg . Trapped solvent preswells the polymer network so that small perturbations to the molecular weight distribution of the PMMA cause it to become soluble in developer. Low molecular weight broad distribution resists similarly prepared are readily soluble in the developer and do not exhibit improved sensitivity in usable lithographic images. When narrowly fractionated PMMA is baked above Tg, the sensitivity is found to be slightly different from broad distribution material, and the contrast is significantly improved. Electron beam exposure of these narrow distribution PMMA resists baked below and above Tg has produced 2000 and 800 Å period gratings, respectively.

Elastic moduli of glassy polymers at low strains

The short time moduli of polystyrene, poly(methyl methyacrylate), and polycarbonate have been measured in the glassy state. The main methods used were as follows: (1) The Young's modulus of a strip was derived by extrapolating to infinite length. (2) A bidirectional strain gauge was used for Young's modulus and Poisson's ratio. (3) A unidirectional bulk modulus was measured by the method of Warfield. The results obtained made it possible to determine all the isotropic moduli including the bulk modulus, and these are compared with those reported in the literature. Poisson's ratio (v) was found to increase with temperature in all cases. For poly(methyl methacrylate), where results reported in the literature vary widely, our values agreed with the lower reported figures (v < 0.36). The Young's modulus of poly(methyl methacrylate) is found to be more dependent on temperature and frequency than with the other two polymers.

Vinyl Polymerization. 282. Vinyl Polymerization Initiated by Dimethylhydroxylamine-Titanous(lll) Chloride Redox System

Abstract The polymerization of vinyl monomers initiated by dimethylhydroxylamine hydrochloride (DHA)-titanous(III) chloride redox system has been studied in water under a nitrogen atmosphere. In the polymerization of methyl methyacrylate (MMA) initiated by the above system, the rate of polymerization has been found to be proportional to [DHA]0.5 for DHA concentrations of less than 2.06 × 10−3 mole/liter, whereas at higher concentrations the rate tends to fall rapidly. The rate has also been found to be proportional to [Ti(m)] 0.58 and to [MMA] 1.0. The maximum rate of polymerization has been observed at a 1:1 molar ratio of DHA to Ti(III). The polymerization proceeded via a radical mechanism. The overall activation energy was estimated as 5.5 kcal/mole. It has been suggested that the reduction of dimethylhydroxylamine by titanous(III) chloride yields the dimethylamino radical, which initiates vinyl polymerization. An examination of the initiating capacity of the initiator system for the polymerization of ...