Methacrylate Graft Research Articles

Characterization of a novel light‐cured star‐shape poly(acrylic acid)‐composed glass‐ionomer cement: fluoride release, water sorption, shrinkage, and hygroscopic expansion

This study evaluated the fluoride release, water sorption, curing shrinkage, and hygroscopic expansion of a novel experimental light-cured glass-ionomer cement. The effects of glycidyl methacrylate (GM) grafting, polymer : water (P : W) and powder : liquid (P : L) ratios were investigated. Commercial Fuji II and Fuji II LC cements were used as controls for comparison. All the specimens were conditioned in deionized water at 37 degrees C before testing. The results demonstrated that the experimental cement showed lower burst and slower bulk fluoride release than Fuji II and Fuji II LC. The experimental cement absorbed more water than Fuji II and Fuji II LC as a result of its hydroxyl and carboxyl functional group content. The lower water-diffusion rate and reduced hygroscopic expansion of the experimental cement suggest that it had a highly crosslinked network. Both Fuji II and Fuji II LC exhibited much higher shrinkage values (2.8% and 4.7%) than the experimental cement (0.8%). It appears that this novel cement will be a clinically attractive dental restorative because not only has it shown superior mechanical strength, it has also demonstrated satisfactory physical properties.

Kinetics of methyl methacrylate grafting polymerization onto flaky aluminum powder

AbstractWith ammonium persulfate (APS) as the initiator, the kinetics of methyl methacrylate (MMA) grafting polymerization onto flaky aluminum powder (Al) was studied. It was found that the experimental apparent grafting polymerization rate, Rg = KC × C × C, was basically consistent with the theoretical result based on the theory of stable polymerization and equivalent activity, Rg = KC × C × CMMA. The activation energy of grafting, homogenous, and total polymerization rate was calculated as 65.1, 35.4, and 37.5 kJ mol−1, respectively. It could be validated that the relationship among these activation energies accorded with the theoretical result of parallel reactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Combinatorial peptide synthesis on a microchip.

Microchips are used in the combinatorial synthesis of peptide arrays by means of amino acid microparticle deposition. The surface of custom-built microchips can be equipped with an amino-modified poly(ethylene glycol)methacrylate (PEGMA) graft polymer coating, which permits high loading of functional groups and resists nonspecific protein adsorption. Specific microparticles that are addressed to the polymer-coated microchip surface in a well defined pattern release preactivated amino acids upon melting, and thus allow combinatorial synthesis of high-complexity peptide arrays directly on the chip surface. Currently, arrays with densities of up to 40,000 peptide spots/cm(2) can be generated in this way, with a minimum of coupling cycles required for full combinatorial synthesis. Without using any additional blocking agent, specific peptide recognition has been verified by background-free immunostaining on the chip-based array. This unit describes microchip surface modification, combinatorial peptide array synthesis on the chip, and a typical immunoassay employing the resulting high-density peptide arrays.

Mechanism of Introduction of Exogenous Genes into Cultured Cells Using DEAE-Dextran-MMA Graft Copolymer as Non-Viral Gene Carrier

Comparative investigations were carried out regarding the efficiency of introduction of exogenous genes into cultured cells using a cationic polysaccharide DEAE-dextran-MMA (methyl methacrylate ester) graft copolymer (2-diethylaminoethyl-dextran-methyl methacrylate graft copolymer; DDMC) as a nonviral carrier for gene introduction. The results confirmed that the gene introduction efficiency was improved with DDMC relative to DEAE-dextran. Comparative investigations were carried out using various concentrations of DDMC and DNA in the introduction of DNA encoding luciferase (pGL3 control vector; Promega) into COS-7 cells derived from African green monkey kidney cells. The complex formation reaction is thought to be directly proportional to the transformation rate, but the complex formation reaction between DDMC and DNA is significantly influenced by hydrophobic bonding strength along with hydrogen bonding strength and Coulomb forces due to the hydrophobicity of the grafted MMA sections. It is thought that the reaction is a Michaelis-Menten type complex formation reaction described by the following equation: Complex amount = K1 (DNA concentration)(DDMC concentration). In support of this equation, it was confirmed that the amount of formed complex was proportional to the RLU value.

Reactive processing of polymers: Structural characterisation of products by 1H and 13C NMR spectroscopy for glycidyl methacrylate grafting onto EPR in the absence and presence of a reactive comonomer

Grafted GMA on EPR samples were prepared in a Thermo-Haake internal mixer by free radical melt grafting reactions in the absence (conventional system; EPR–g–GMA CONV) and presence of the reactive comonomer divinyl benzene, DVB (EPR–g–GMA DVB). The GMA-homopolymer (poly-GMA), a major side reaction product in the conventional system, was almost completely absent in the DVB-containing system, the latter also resulted in a much higher level of GMA grafting. A comprehensive microstructure analysis of the formed poly-GMA was performed based on one-dimensional 1H and 13C NMR spectroscopy and the complete spectral assignments were supported by two-dimensional NMR techniques based on long range two and three bond order carbon–proton couplings from HMBC (Heteronuclear Multiple Bond Coherence) and that of one bond carbon–proton couplings from HSQC (Heteronuclear Single Quantum Coherence), as well as the use of Distortionless Enhancement by Polarization Transfer (DEPT) NMR spectroscopy. The unambiguous analysis of the stereochemical configuration of poly-GMA was further used to help understand the microstructures of the GMA-grafts obtained in the two different free radical melt grafting reactions, the conventional and comonomer-containing systems. In the grafted GMA, in the conventional system (EPR–g–GMA CONV), the methylene protons of the GMA were found to be sensitive to tetrad configurational sequences and the results showed that 56% of the GMA sequence in the graft is in atactic configuration and 42% is in syndiotactic configuration whereas the poly-GMA was predominantly syndiotactic. The differences in the microstructures of the graft in the conventional EPR–g–GMA CONV and the DVB-containing (EPR–g–GMA DVB) systems is also reported

Synthesis of Norbornene and Methyl Methacrylate Graft Copolymers with High Norbornene Content by Using Mixed Catalytic System

A vinyl-type polymer of norbornene containing a few pendant styrene groups obtained by copolymerization of norbornene and 1,4-divinylbenzene (1,4-DVB) was used as a macroinitiator in the reverse atom transfer radical polymerization (RATRP) of methyl methacrylate in conjunction with CuCl2/2,2′-bipyridine/2,2′-azobisisobutyronitrile (AIBN) as a catalyst. In the first step of the reaction, the structural characterization of the copolymers showed that norbornene and 1,4-divinylbenzene copolymerizations occur as a coordination mechanism and that true copolymers are formed by random copolymerization. With the initiation of copper dichloride and AIBN in the second step, the pendant styrene groups in the copolymers were quantitatively polymerized with methyl methacrylates, which allowed the successful synthesis of polynorbornene-based graft copolymers by RATRP mechanism. The analyses of the product by 1H-and 13C-NMR and GPC gel permeation chromatography (GPC) gave the verification of ‘true’ copolymer. Varying the monomer feed ratio controlled the thermal property of the graft copolymer.

Effects of methyl methacrylate grafting and in situ silica particle formation on the morphology and mechanical properties of natural rubber composite films

AbstractThe effects of methyl methacrylate (MMA) grafting and in situ formation of silica particles on the morphology and mechanical properties of natural rubber latex (NRL) were investigated. MMA grafting on NRL was carried out using cumyl hydroxy peroxide/tetraethylene pentamine (CHPO/TEPA) as a redox initiator couple. The grafting efficiency of the grafted NR was determined by solvent extractions and the grafted NRL was then mixed with tetraethoxysilane (TEOS), a precursor of silica, coated by adherence to a glass surface to form a film and cured at 80°C. The resultant products were characterized by FT‐IR and transmission electron microscopy. The influence of varying the MMA monomer weight ratio on the surface morphology of the composites was investigated by scanning electron and atomic force microscopy. The PMMA (poly MMA) grafted NRL particles were obtained as a core/shell structure from which the NR particles were the core seed and PMMA was a shell layer. The silane was converted into silica particles by a sol–gel process which was induced during film drying at 80°C. The silica particles were fairly evenly distributed in the ungrafted NR matrix but were agglomerated in the grafted NR matrix. The root‐mean‐square roughness increased with an increasing weight ratio of MMA in the rubber. The in situ silica particles in the grafted NR matrix slightly increased both the modulus and the tear strength of the composite film. Copyright © 2008 John Wiley & Sons, Ltd.

Surface modification of cellulose filter paper by glycidyl methacrylate grafting for biomolecule immobilization: Influence of grafting parameters and urease immobilization

AbstractGraft copolymerization of glycidyl methacrylate (GMA) onto cellulose filter paper (CFP) was carried out by a free‐radical initiating process using ceric ammonium nitrate (CAN) as an initiator. Optimum conditions pertaining to different grafting percentages were evaluated as a function of monomer and initiator concentrations, polymerization time and temperature. CFP with various graft levels of GMA was characterized by fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA). Surface morphology of ungrafted and grafted CFP was evaluated by scanning electron microscopy (SEM). Attenuated total reflectance (ATR)‐FTIR spectral analysis provided the evidence of grafting of GMA onto CFP. The maximum grafting of 102% was achieved by using 4 × 10−3 molL−1 CAN and 5% of GMA (w/v) monomer at 60°C in 25 min. The CFP‐g‐GMA surfaces with different graft levels were evaluated as a support for immobilization of biomolecules. Urease was selected as the model enzyme to be covalently coupled through the surface epoxy groups of the CFP‐g‐GMA discs. Immobilized discs were further studied for urea estimation and their reusability. Although the highest degree of urease immobilization was observed at 100% (162‐μg urease/disc) graft level, the urease immobilized on discs with 70% (105‐μg urease/disc) graft level gave the maximum activity of the enzyme. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Production of carboxyl-containing derivatives of polymethyl methacrylate and polycaproamide graft copolymer

In studying heterophase alkaline hydrolysis of ester groups in graft PMMA chains, the role of the structure of the polymer in the macromolecular reaction in the solid phase was revealed. A decrease in the degree of conversion of graft PMMA with an increase in its content in PCA—PMMA graft copolymer, caused by a change in the packing density of the graft chains, was established. The highest degree of saponification was attained in using graft copolymers containing 25–35% graft PMMA. Chemisorption, carboxyl-containing polycaproamide fibre with a SEC for NaOH of 1.3 mmole/g was obtained as a result of saponification of PCA—PMMA graft copolymers.

Grafting of glycidyl methacrylate onto high‐density polyethylene with reaction time in the batch mixer

AbstractThe melt grafting of glycidyl methacrylate (GMA) onto high‐density polyethylene (HDPE) in the presence of free radical initiators was investigated in the batch mixer. The graft content was determined with the titration and FTIR spectroscopy. The graft content increased with the increase of peroxide and initially introduced GMA concentration. Increase of the grafted GMA content resulted in decrease of the melt index. Interestingly, there was a sudden drop of GMA grafting content with the reaction time. It is assumed that depolymerization of GMA have taken place over the ceiling temperature. The crystallinity of the prepared glycidyl methacrylate grafted high density polyethylene (HDPE‐g‐GMA) was determined by the measurement of the heat of fusion. GMA grafted site acted as defect and crystallinity of the HDPE‐g‐GMA decreased with the increase of grafting reaction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Protein separation by open tubular capillary electrochromatography employing a capillary coated with phenylalanine functionalized tentacle-type polymer under both cathodic and anodic electroosmotic flows

The use of a phenylalanine (Phe) functionalized tentacle-type polymer coated capillary column for protein separation by open tubular capillary electrochromatography (OTCEC) was demonstrated in this work. The tentacle-type stationary phase was prepared from silanized fused-silica capillaries of 50 μm I.D. by glycidyl methacrylate graft polymerization and subsequent Phe functionalization. Due to the amphoteric functional groups of the Phe bonded on the tentacle-type polymer stationary phase, protein separation in the prepared column can be performed under both cathodic and anodic electroosmotic flow (EOF) by varying the pH values of the mobile phase. Model proteins including ribonuclease A (RNase A), myoglobin, transferrin, insulin were baseline separated under cathodic EOF with a mobile phase of pH 8.8. Comparison between the separation result of the four proteins under conditions of OTCEC and capillary zone electrophoresis indicates that the migration behavior of the four proteins in the prepared column was the result of the interplay of chromatographic retention and electrophoretic migration. Besides, three basic proteins including RNase A, cytochrome c (Cyt- c) and lysozyme (Lys) were fully resolved under anodic EOF with an acidic running buffer (pH 2.5). The elution order was the same as the isoelectric point values of the proteins (RNase A < Cyt- c < Lys). Moreover, it was proved that the migration times of all the proteins used in this work were stable in repeated uses of the column, and the column efficiency of proteins was in the range from 13,000 to 182,000 plates/m.

Characteristics of DEAE-dextran-MMA graft copolymer as a nonviral gene carrier

A stable and soapless latex of diethylaminoethyl-dextran-methyl methacrylate (DEAE-dextran-MMA) graft copolymer (DDMC) has been developed for nonviral gene delivery vectors that are possible to autoclave. DDMC relatively easily formed a polyion complex between DNA and DDMC by the hydrophobic force of graft poly(MMA) depending on its large positive entropy change (ΔS). DDMC has been confirmed as having a high protection facility for DNase by DNase degradation test.Transfection activity was determined using the β-galactosidase assay, and a higher value of 16 times or more was confirmed for the DDMC samples in comparison with one of the starting DEAE-dextran hydrochloride samples. The resulting DDMC, having an amphiphilic domain so as to form a polymer micelle, should become a stable latex with a hydrophilic-hydrophobic microseparated domain. The complex of DDMC and plasmid DNA may be formed on the spherical structure of the amphiphilic microseparated domain of DDMC and have a good affinity to the cell membrane. The infrared absorption spectrum shift to a high-energy direction at around 3450 cm –1, because of the complexes between DNA and DDMC, may cause the formation of more compact structures, not only by a coulomb force between the phosphoric acid of DNA and the DEAE group of DEAE-dextran copolymer but also by a force from the multi-intermolecule hydrogen bond in the backbone polymer DEAE-dextran and a hydrophobic force from the graft poly(MMA) in DDMC. It is thus concluded that DNA condensation may possibly have a high transfection efficiency via DDMC. The high efficiency of this graft copolymer, which is sterilized by an autoclave, may thus make it a valuable tool for safe gene delivery.

Multifunctional CMOS Microchip Coatings for Protein and Peptide Arrays

Complementary metal oxide semiconductor (CMOS) microelectronic chips fulfill important functions in the field of biomedical research, ranging from the generation of high complexity DNA and protein arrays to the detection of specific interactions thereupon. Nevertheless, the issue of merging pure CMOS technology with a chemically stable surface modification which further resists interfering nonspecific protein adsorption has not been addressed yet. We present a novel surface coating for CMOS microchips based on poly(ethylene glycol)methacrylate graft polymer films, which in addition provides high loadings of functional groups for the linkage of probe molecules. The coated microchips were compatible with the harshest conditions emerging in microarray generating methods, thoroughly retaining structural integrity and microelectronic functionality. Nonspecific adsorption of proteins on the chip's surface was completely obviated even with complex serum protein mixtures. We could demonstrate the background-free antibody staining of immobilized probe molecules without using any blocking agents, encouraging further integration of CMOS technology in proteome research.

Grafting of methacrylates and styrene on to polystyrene backbone via a “grafting from” ATRP process at ambient temperature

AbstractWell defined graft copolymers are prepared by “grafting from” atom transfer radical polymerization (ATRP) at room temperature (30 °C). The experiments were aimed at grafting methacrylates and styrene at latent initiating sites of polystyrene. For this purpose, the benzylic hydrogen in polystyrene was subjected to allylic bromination with N‐bromosuccinimide and azobisisobutrylnitirle to generate tertiary bromide ATRP initiating sites (BrCPS). The use of BrCPS with lesser mol % of bromide initiating groups results in better control and successful graft copolymerization. This was used to synthesize a series of new graft copolymers such as PS‐g‐PBnMA, PS‐g‐PBMA, PS‐g‐GMA, and PS‐g‐(PMMA‐b‐PtBA) catalyzed by CuBr/PMDETA system, in bulk, at room temperature. The polymers are characterized by GPC, NMR, FTIR, TEM, and TGA. Graft copolymerization followed by block polymerization enabled the synthesis of highly branched polymer brush, in which the grafting density can be adjusted by appropriate choice of bromide concentration in the polystyrene. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3818–3832, 2007

Effect of surface modification of polymer beads on the mechanical properties of acrylic bone cement

The effect of surface modification of polymer filler on the static mechanical properties of acrylic bone cement was studied. The surface of polymer beads was modified with carboxylic and amino groups by photochemical reaction with azide compounds. Monomer modifiers (maleic anhydride, methacrylic acid and p-aminostyrene) are attached to the functionalized surface of polymer beads. Functional allyl groups, which are capable of the graft polymerisation reaction, are attached to the surface via photochemical reaction with N-(2-nitro-4-azidophenyl)-N-(-propen) amine. This approach to bone cement provides the additional covalent bonds between the polymer beads and the inter-bead matrix. The static mechanical properties of bone cements containing modified polymer beads were investigated and compared with the static mechanical properties of unmodified cements. The absolute values of compressive strength for the modified and unmodified cements were found to be similar. An increase in flexural strength for the modified cements (dry and after water storage) was observed. The structure of the surface functional groups affects the methyl methacrylate grafting resulting in a higher value of flexural strength for the maleic anhydride- and p-aminostyrene-modified cements. The scanning electron microscopy examination of the fracture surface of the cement samples showed an improvement of the adhesion between the beads and the matrix after modification.

Effects of cross-linking molecular weights in a hyaluronic acid–poly(ethylene oxide) hydrogel network on its properties

We examined the effects of cross-linking molecular weights on the properties of a hyaluronic acid (HA)–poly(ethylene oxide) (PEO) hydrogel. Swelling behaviors, mechanical strength and rheological behaviors of the HA–PEO hydrogel were evaluated by employing different cross-linking molecular weights (100 kDa and 1.63 mDa) of the HAs in the hydrogel networks. The low molecular weight of HA was obtained in advance by treating high molecular weight HA with a hydrogen chloride solution. Methacrylation of HA was obtained by grafting aminopropylmethacrylate to its caroboxylic acid functional groups. While reduction of the HA molecular weights was confirmed by gel permeation chromatography, the degree of methacrylate grafting to the HA was measured by 1H-nuclear magnetic resonance. Synthesis of the HA–PEO hydrogel was successfully achieved via the Michael-type addition reaction between the methacrylate arm groups in the HA and the six thiol groups in PEO. The hydrogel formation was not dependent upon the HA molecular weights and its gelation behaviors were markedly different. Compared to the properties of the high molecular weight HA-based PEO one, the low molecular weight HA-based hydrogel induced quicker hydrogelation, as observed from the behaviors of the elastic and viscous modulus. Furthermore, the low molecular weight HA-based hydrogel demonstrated stronger mechanical properties as measured with a texture analyzer, lower water absorption as measured with a microbalance and smaller pore sizes on its surface and cross section as observed with scanning electron microscopy. The information about the effects of the cross-linking molecular weights of the gel network on the properties of the HA-based PEO hydrogel may lead to better design of hydrogels, especially in tissue engineering applications.

Swelling behavior of gelatin-g-methyl methacrylate copolymers

Gelatin-methyl methacrylate graft copolymers were prepared with gelatin and methyl methacrylate (MMA). The effect of various reaction parameters on the swelling behavior was investigated systematically, such as the concentration of the monomer, the content of the initiator, reaction time and temperature. In addition, the effect of intercalation of graft copolymers with montmorillonite (MMT) on swelling behavior was studied. The results indicated that the graft copolymerization and intercalation with MMT could greatly reduce the swelling degree of gelatin. The swelling process of the copolymers followed second-order kinetics identical to that of the original gelatin.

Synthesis and characterization of 2‐diethyl‐aminoethyl–dextran–methyl methacrylate graft copolymer for nonviral gene delivery vector

AbstractA stable and soapless latex of 2‐diethyl‐aminoethyl (DEAE)–dextran–methyl methacrylate (MMA) graft copolymer (DDMC) was developed for nonviral gene delivery vectors (complex between polycation and nucleic acid). DDMC was newly prepared using MMA and DEAE–dextran. Following a transfection protocol, transfection of HEK 293 cells by DDC1, DDC2, and DDC3 samples was carried out using plasmid DNA. With the transfection efficiency determined using the X‐Gal staining method, a higher value of 5 times or more was confirmed for DDMC samples DDC1 and DDC2 (but not for DDC3) than for the starting DEAE–dextran hydrochloride. The absorption spectrum shift at around 3400 cm−1 of the complexes between DDMC and DNA may support the formation of more compact structures by a Coulomb force between the phosphoric acid of DNA and the DEAE group of DEAE–dextran, concluding in DNA condensation. The specifically designed molecular structure of DDMC to ensure easy entry of DNA into cells needs not only a positive charge and a hydrophilic–hydrophobic microseparated domain but also more compact structures for transfection steps. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 9–14, 2005

Hydrophilic Treatment of the Dyed Nylon-6 Fabric using High-density and Extensible Antenna-coupling Microwave Plasma System

High density and well surface-distributed oxygen microwave plasma with an extensible antenna-coupling design was utilized to modify a densely weaved and large-surface-area Nylon-6 fabric within a short treatment time. Plasma pretreatment and subsequent acrylic acid (AAc) or 2-hydroxyethyl methacrylate (HEMA) grafting process were studied and optimized at the stage after dyed and finished procedure. The monomer-grafted dyed Nylon-6 fabrics evolved lasting hydrophilic properties and thereafter created or improved surface properties such as water diffusion, drainage, moisture regain and water absorbency, in different degrees. The pHEMA-grafted sample exhibited minor effect in color perception, which was also much hydrophilic than the pAAc-grafted one. Based upon surface analyses and wetting assessment, the penetration of HEMA monomer into the plasma-treated fabric matrix contributed to the facilitation of wetting properties. This work accordingly ensures such plasma-induced system to incorporate with the pattern of hydrophilic properties on the analogous textiles without interrupting their finishing process.

Characterization of Methyl Methacrylate Grafting onto Preirradiated Biodegradable Lignocellulose Fiber by γ‐Radiation

Gamma-radiation-induced graft copolymerization of methyl methacrylate onto natural lignocellulose (jute) fiber was carried out by the preirradiation method in an aqueous medium by using octylphenoxy-polyethoxyethanol as an emulsifier. The different factors that influenced the graft copolymer reaction process were investigated. In the case of radiation-dose-dependent grafting, samples irradiated in the presence of air produced up to 73% graft weight compared to 53% obtained in the case of irradiation in a nitrogen environment. By assuming Arrhenius reaction kinetics, the activation energy (E(a)) of the grafting reaction process was evaluated for different reaction temperatures. Moreover, the graft copolymer reaction was controlled by incorporating a homopolymer-inhibiting agent and three different chain-transfer agents in the reaction medium. The mechanical and thermal properties of jute fiber 'as received' and jute-graft-poly(methyl methacrylate) were also investigated. The results showed that the percentage of grafting with jute fiber has a significant effect on the properties. The kinetic parameters were evaluated from TGA thermograms by using Broido's method in the temperature range 240-350 degrees C. Scanning electron micrographs show that the structural changes on the surface of jute fibers were induced by graft copolymerization of methyl methacrylate monomer. Fiber-fiber surface friction was measured in terms of the average maximum load and the kinetic friction. SEM of jute-graft-poly(methyl methacrylate).