Showing papers on "Glycidyl methacrylate published in 2012"

Synergetic effect of thermal conductive properties of epoxy composites containing functionalized multi-walled carbon nanotubes and aluminum nitride

Abstract: This study investigates the thermal conductivity of epoxy composites containing two hybrid fillers which are multi-walled carbon nanotubes (MWCNTs) and aluminum nitride (AlN). To form a covalent bonds between the fillers and the epoxy resin, poly(glycidyl methacrylate) (PGMA) were grafted onto the surface of nano-sized MWCNTs via free radical polymerization and micro-sized AlN was modified by zirconate coupling agent. Results show that functionalized fillers improve thermal conductivity of epoxy composites, due to the good dispersion and interfacial adhesion, which is confirmed by scanning electron microscope. Furthermore, the hybrid fillers provide synergetic effect on heat conductive networks. The thermal conductivity of epoxy composites containing 25 vol.% modified AlN and 1 vol.% functionalized MWCNTs is 1.21 W/mK, comparable to that of epoxy composites containing 50 vol.% untreated AlN (1.25 W/mK), which can reduce the half quantity of AlN filler used.

How Does Cross-Linking Affect the Stability of Block Copolymer Vesicles in the Presence of Surfactant?

Abstract: Block copolymer vesicles are conveniently prepared directly in water at relatively high solids by polymerization-induced self-assembly using an aqueous dispersion polymerization formulation based on 2-hydroxypropyl methacrylate. However, dynamic light scattering studies clearly demonstrate that addition of small molecule surfactants to such linear copolymer vesicles disrupts the vesicular membrane. This causes rapid vesicle dissolution in the case of ionic surfactants, with nonionic surfactants proving somewhat less destructive. To address this problem, glycidyl methacrylate can be copolymerized with 2-hydroxypropyl methacrylate and the resulting epoxy-functional block copolymer vesicles are readily cross-linked in aqueous solution using cheap commercially available polymeric diamines. Such epoxy-amine chemistry confers exceptional surfactant tolerance on the cross-linked vesicles and also leads to a distinctive change in their morphology, as judged by transmission electron microscopy. Moreover, pendent u...

Chemical modification of simul wood with styrene–acrylonitrile copolymer and organically modified nanoclay

Abstract: Simul wood (Salmalia malabarica) was chemically modified by treatment with styrene–acrylonitrile copolymer (SAN), glycidyl methacrylate (GMA), and organically modified nanoclay. The physical properties of wood polymer composites (WPC) were improved due to the addition of GMA and nanoclay. XRD analysis indicated a decrease in crystallinity in WPC. FTIR study confirmed the presence of clay in WPC. The presence of clay in cell lumen and cell wall was evidenced by SEM study. WPC containing lower percentage of clay showed better thermal stability compared to WPC loaded with higher percentage of clay.

Interconnected macroporous glycidyl methacrylate-grafted dextran hydrogels synthesised from hydroxyapatite nanoparticle stabilised high internal phase emulsion templates

Abstract: Commercially available hydroxyapatite (HAp) nanoparticles were used as sole emulsifiers to produce stable methyl myristate-in-water and soybean oil-in-water high internal phase emulsions (HIPEs). The droplet size in the Pickering inverse HIPEs (i-HIPEs) could be adjusted within a certain range by tailoring the energy input during emulsification and emulsifier concentrations. These HAp nanoparticle stabilised i-HIPEs were then used as templates to synthesise interconnected high porosity macroporous hydrogels by crosslinking glycidyl methacrylate (GMA) functionalised dextran, which was dissolved in the continuous aqueous phase of the i-HIPEs. The pore size of these polyPickering-HIPE hydrogels could be adjusted by the emulsifier concentration, oil type, emulsification conditions or ripening time of the i-HIPE templates.

Effect of Nano-ZnO on Thermal, Mechanical, UV Stability, and Other Physical Properties of Wood Polymer Composites

Abstract: Wood polymer nanocomposite (WPNC) was prepared by impregnation of styrene-acrylonitrile copolymer (SAN) of 2:3 molar ratio, vinyl trichlorosilane (VTCS) modified ZnO nanoparticles and glycidyl methacrylate (GMA) as a cross-linking agent into cellular structure of wood. The surface modification of ZnO nanoparticles and the properties of the WPNC were investigated by XRD, FTIR, TGA, SEM and TEM. The mechanical properties including modulus of rupture (MOR), tensile strength and hardness, and multifunctional properties involving UV resistance, water resistance, dimensional stability and thermal stability were studied. The nano-ZnO particles dispersed uniformly in the polymer filled in the porous structure of wood, as evidenced by SEM-EDX and FTIR, respectively. TEM study showed the homogeneous dispersion of ZnO nanoparticles on the cell wall of wood with SAN polymer matrix.

Improvement of dimensional stability of wood via combination treatment: swelling with maleic anhydride and grafting with glycidyl methacrylate and methyl methacrylate

Abstract: Abstract A novel two-step combined treatment of poplar wood was developed to improve its dimensional stability. Maleic anhydride (MAN) was first employed to swell and bond to the wood cell wall, and then mixed monomers of glycidyl methacrylate/methyl methacrylate (GMA/MMA) were grafted to the cell wall through the chemical reaction with MAN within the wood cell lumen. The results of scanning electron microscopy and energy dispersive X-ray apparatus (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR) analyses indicate that MAN penetrated and chemically bonded to the cell wall causing 9% volume swelling, and the copolymer from GMA/MMA monomers was grafted onto the wood cell wall, resulting in the improved interfacial compatibility between the polymer and wood matrix. The dimensional stability of poplar wood modified by the combined two-step treatment was remarkably improved compared with that of untreated poplar wood. The combination treatment of wood employed in this study proved to be more effective for improving the dimensional stability than treatment with PEG-1000 aqueous solution with 30% concentration.

The Mechanical Properties of Epoxy Composites Filled with Rubbery Copolymer Grafted SiO 2

Abstract: This study demonstrated a method for toughening a highly crosslinked anhydride cured DGEBA epoxy using rubbery block copolymer grafted SiO2 nanoparticles. The particles were synthesized by a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. The inner rubbery block poly(n-hexyl methacrylate) (PHMA) had a glass transition temperature below room temperature. The outer block poly(glycidyl methacrylate) (PGMA) was matrix compatible. A rubbery interlayer thickness of 100% and 200% of the particle core radius was achieved by grafting a 20 kg/mol and a 40 kg/mol PHMA at a graft density of 0.7 chains/nm 2 from the SiO2 surface. The 20 kg/mol rubbery interlayer transferred load more efficiently to the SiO2 cores than the 40 kg/mol rubbery interlayer and maintained the epoxy modulus up to a loading of 10 vol% of the rubbery interlayer. Both systems enabled cavitation or plastic dilatation. Improvement of the strain-to-break and the tensile toughness was found in both systems. We hypothesize that plastic void growth in the matrix is the primary mechanism causing the improvement of the ductility.

In situ preparation of silver nanoparticles on biocompatible methacrylated poly(vinyl alcohol) and cellulose based polymeric nanofibers

Abstract: Ultra-fine nanofiber mats of cellulosic polymer and polyvinyl alcohol (PVA) containing silver (Ag) nanoparticles were fabricated using the electrospinning technique. Polymers with hydroxyl groups on the backbone such as PVA, PVA/dextran and PVA/methyl cellulose were chosen for this study. All polymers showed the ability to reduce silver nitrate (AgNO3) to Ag-nanoparticles. To make crosslinkable networks of the water soluble polymers, the photo-crosslinkable glycidyl methacrylate moiety was attached to the hydroxyl groups of the designed macromers. AgNO3 and cytocompatible initiator (IRGACURE 2959) were added to the methacrylated polymeric solution mixture before electrospinning. The fiber morphology of the resultant nanofiber was characterised using scanning electron microscopy (SEM) and an average diameter in the range of 300 to 500 nm was observed. The resultant nanofibers containing Ag-ions and initiators were crosslinked under photoirradiation at a wavelength of 365 nm for 6 h and heated at 100 °C for 6 h for complete reduction of Ag-ions into Ag-nanoparticles. Transmission electron microscopy (TEM) analysis revealed that the Ag-nanoparticles with an average diameter of 10 to 20 nm were uniformly distributed throughout the nanofibers and its presence was confirmed using X-ray diffraction analysis. The effect of Ag-nanoparticles on the microcrystalline structure of the polymer was studied by thermal and mechanical properties analysis. The biocompatibility of the methacrylated macromers was investigated using human lung fibroblasts (IMR-90) and no cytotoxic effects were found after 4 days of incubation. The antimicrobial activity of the PVA nanofiber containing Ag-nanoparticles was tested against Escherichia coli. The nanofiber containing Ag-nanoparticles may have potential applications in biomedical devices which will be explored in the near future.

Grafting of Glycidyl Methacrylate onto Poly(lactide) and Properties of PLA/Starch Blends Compatibilized by the Grafted Copolymer

Abstract: Poly(lactide)-graft-glycidyl methacrylate (PLA-g-GMA) copolymer was prepared by grafting GMA onto PLA in a batch mixer using benzoyl peroxide as an initiator The graft content was determined with the 1H-NMR spectroscopy by calculating the relative area of the characteristic peaks of PLA and GMA The result shows that the graft content increases from 18 to 110 wt% as the GMA concentration in the feed varies from 5 to 20 wt% The PLA/starch blends were prepared by the PLA-g-GMA copolymer as a compatibilizer, and the structure and properties of PLA/starch blends with or without the PLA-g-GMA copolymer were characterized by SEM, DSC, tensile test and medium resistance test The result shows that the PLA/starch blends without the PLA-g-GMA copolymer show a poor interfacial adhesion and the starch granules are clearly observed, nevertheless the starch granules are better dispersed and covered by PLA when the PLA-g-GMA copolymer as a compatibilizer The mechanical properties of the PLA/starch blends with the PLA-g-GMA copolymer are obviously improved, such as tensile strength at break increasing from 186 ± 38 MPa to 293 ± 58 MPa, tensile modulus from 510 ± 62 MPa to 901 ± 62 MPa and elongation at break from 18 ± 04 % to 34 ± 06 %, respectively, for without the PLA-g-GMA copolymer In addition, the medium resistance of PLA/starch blends with the PLA-g-GMA copolymer was much better than PLA/starch blends

Preparation and Characterization of Polyester–Glycidyl Methacrylate PolyHIPE Monoliths to Use in Heavy Metal Removal

Abstract: Polyester–glycidyl methacrylate (GMA)-based poly(high internal phase emulsion)s (polyHIPEs) with 85% internal phase were prepared by using unsaturated polyester resin (UPR), glycidyl metahacrylate and divinylbenzene (DVB) or styrene (St) with triethanolamine (TEA) as an emulsifier in the presence of a porogen. Porous monoliths were obtained by a removal of internal phase after curing of dispersed phase at 80°C. Morphologies and surface properties of obtained porous monoliths were investigated by scanning electron microscopy (SEM) and Brunauner–Emmet–Teller (BET) molecular adsorption methods. Amine functionalization of epoxy groups of polyHIPEs was achieved by reactions with several amines such as 1,4-ethylenediamine (EDA), 1,6-hexamethylenediamine (HMDA), 4-aminosalicylic acid (ASA), 2-aminothiazole (ATAL), 4-aminobenzothiazole (ABTAL) and 2-phenylimidazole (PIAL), respectively. The functionalized polyHIPEs were characterized by elemental analysis and the best result was obtained with the 1,4-ethylenediam...

Hydrogels based on chemically modified poly(vinyl alcohol) (PVA-GMA) and PVA-GMA/chondroitin sulfate: Preparation and characterization

Abstract: This work reports the preparation of hydrogels based on PVA-GMA, PVA-GMA is poly(vinyl alcohol) (PVA) functionalized with vinyl groups from glycidyl methacrylate (GMA), and on PVA-GMA with different content of chon- droitin sulfate (CS). The degrees of swelling of PVA-GMA and PVA-GMA/CS hydrogels were evaluated in distilled water and the swelling kinetics was performed in simulated gastric and intestinal fluids (SGF and SIF). PVA-GMA and PVA- GMA/CS hydrogels demonstrated to be resistant on SGF and SIF fluids. The elastic modulus, E, of swollen-hydrogels were determined through compressive tests and, according to the obtained results, the hydrogels presented good mechanical properties. At last, the presence of CS enhances the hydrogel cell compatibility as gathered by cytotoxicity assays. It was concluded that the hydrogels prepared through this work presented characteristics that allow them to be used as biomaterial, as a carrier in drug delivery system or to act as scaffolds in tissue engineering as well.

Immobilization of gelatin onto poly(glycidyl methacrylate)-grafted polycaprolactone substrates for improved cell-material interactions

Abstract: To enhance the cytocompatibility of polycaprolactone (PCL), cell-adhesive gelatin is covalently immobilized onto the PCL film surface via two surface-modified approaches: a conventional chemical immobilization process and a surface-initiated atom transfer radical polymerization (ATRP) process. Kinetics studies reveal that the polymer chain growth from the PCL film using the ATRP process is formed in a controlled manner, and that the amount of immobilized gelatin increases with an increasing concentration of epoxide groups on the grafted P(GMA) brushes. In vitro cell adhesion and proliferation studies demonstrate that cell affinity and growth are significantly improved by the immobilization of gelatin on PCL film surfaces, and that this improvement is positively correlated to the amount of covalently immobilized gelatin. With the versatility of the ATRP process and tunable grafting efficacy of gelatin, this study offers a suitable methodology for the functionalization of biodegradable polyesters scaffolds to improve cell–material interactions.

Synthesis of polylactide‐graft‐glycidyl methacrylate graft copolymer and its application as a coupling agent in polylactide/bamboo flour biocomposites

Abstract: In this study, a novel graft copolymer, polylactide-graft-glycidyl methacrylate (PLA–GMA), was synthesized by the grafting of glycidyl methacrylate onto the polylactide (PLA) chain via free-radical polymerization. Fourier transform infrared spectroscopy and 1H-NMR were used to characterize the structure of the copolymer. Furthermore, PLA–GMA was used as a coupling agent to improve the interfacial adhesion between bamboo flour (BF) and PLA in PLA/BF biocomposites. The mechanical properties and crystallization behavior of the PLA/BF biocomposites were investigated. The results show that with the addition of PLA–GMA, the flexural strength and flexural modulus of the biocomposites increased significantly. The mechanical properties increased with increasing PLA–GMA amount. The PLA–GMA also enhanced the crystallization rate of PLA in the PLA/BF biocomposites. The property improvement of the biocomposites was due to enhanced interfacial adhesion between the PLA and BF. This was confirmed by scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012

Manipulating Interfaces through Surface Confinement of Poly(glycidyl methacrylate)-block-poly(vinyldimethylazlactone), a Dually Reactive Block Copolymer

Abstract: The assembly of dually reactive, well-defined diblock copolymers incorporating the chemoselective/functional monomer, 4,4-dimethyl-2-vinylazlactone (VDMA) and the surface-reactive monomer glycidyl methacrylate (GMA) is examined to understand how competition between surface attachment and microphase segregation influences interfacial structure. Reaction of the PGMA block with surface hydroxyl groups not only anchors the copolymer to the surface, but limits chain mobility, creating brush-like structures comprising PVDMA blocks, which contain reactive azlactone groups. The block copolymers are spin coated at various solution concentrations and annealed at elevated temperature to optimize film deposition to achieve a molecularly uniform layer. The thickness and structure of the polymer thin films are investigated by ellipsometry, infrared spectroscopy, and neutron reflectometry. The results show that deposition of PGMA-b-PVDMA provides a useful route to control film thickness while preserving azlactone groups...

Photopolymerised methacrylate-based emulsion-templated porous polymers

Abstract: Highly porous and interconnected methacrylate-based porous materials were prepared by photopolymerisation of the continuous phase of high internal phase emulsion (HIPE) templates. The rapid cure afforded by photopolymerisation effectively ‘locks’ the emulsion morphology prior to emulsion destabilisation, in comparison to thermally-initiated HIPEs of similar compositions. Contrary to expectation, it was observed that fully cured photopolymerised polyHIPEs could be prepared with a thickness of up to 35 mm, despite the severe opacity of the parent emulsions. This is attributed to a photofrontal polymerisation process, where radicals generated on the surface propagate rapidly through the bulk of the emulsion. Homogeneous, well-defined polyHIPE materials of up to 95% nominal porosity were obtained by photopolymerisation of HIPEs containing up to 30 vol.% glycidyl methacrylate (GMA) in the monomer phase (the remaining monomers and crosslinker are acrylates). Surprisingly, poly(ethylene glycol) methacrylate (PEG-MA), a nonionic monomer that is miscible with both emulsion phases, could be added to such HIPEs after preparation. On polymerisation, hydrophilic, water-wettable porous materials were obtained. Finally, it was also demonstrated that all-methacrylate HIPEs could be prepared and cured to yield GMA-containing polyHIPEs. These findings demonstrate the versatility of photopolymerisation for the preparation of emulsion templated porous polymers.

Release of interfacial thermal stress and accompanying improvement of interfacial adhesion in carbon fiber reinforced epoxy resin composites: Induced by diblock copolymers

Abstract: In this work, diblock copolymer Hydroxyl-Terminated poly (n-butylacrylate)-b-poly (glycidyl methacrylate) (OH-PnBA-b-PGMA) was synthesized by atom transfer radical polymerization (ATRP) and was then introduced into the interface between carbon fiber and epoxy resin. Micro-Raman spectroscopy and microbond test were employed to study the influence of grafted polymers on the interfacial properties. From the Micro-Raman spectroscopy results, the interfacial thermal stress in carbon fiber/epoxy resin micro-composite decreases from 546.9 MPa to 451.9 MPa due to the grafting of OH-PnBA 180 -b-PGMA 70 on the carbon fiber. Meanwhile, the interfacial shear strength (IFSS) value increases rapidly from 29.8 MPa to 52.3 MPa, measured by microbond test. Therefore, it can be concluded that such a diblock copolymer can effectively both release the thermal stress and improve the interfacial adhesion. Moreover, it proves that the length of PnBA block has great influence on the interfacial properties of carbon fiber/epoxy composite.