Effect Of Monomer Composition Research Articles

Effect of monomer composition and filler fraction on surface microhardness and depth of cure of experimental resin composites.

This study evaluated microhardness profiles and calculated depths of cure at 80% of the surface microhardness of experimental dental resin composites having different base monomer compositions and different filler fractions. Composites were prepared using four different base monomers (bisphenol A-glycidyl methacrylate [Bis-GMA], urethane dimethacrylate [UDMA], ethoxylated bisphenol-A dimethacrylate [Bis-EMA], and Fit-852) with triethylene glycol dimethacrylate (TEGDMA) used as a co-monomer at three filler:resin matrix weight percent fractions (50:50, 60:40, and 70:30). Uncured material was placed in 3D printed molds and light cured for 40 s from the top surface only. Knoop microhardness was measured at the top of the specimen, and at every 0.5mm up to 4mm in depth. Microhardness at the surface increased in all experimental composites as the filler fraction increased. When comparing base monomers, microhardness was the highest in UDMA-based composites, while Bis-GMA-based composites showed the lowest values. When comparing depth of cure as a function of base monomer type, both Bis-GMA and Bis-EMA showed significantly lower values than UDMA or Fit-852. Composites having 50wt% filler showed a significantly higher depth of cure than those with 60 and 70wt% filler. Base monomer and filler fraction significantly influence microhardness and depth of cure in these experimental composites.

Effect of monomer composition on thermal, mechanical, and self-healing properties of thermosets containing Diels-Alder adduct moieties and disulfide bonds

The Diels-Alder (DA) and thiol-maleimide reactions of difurfuryl disulfide (DFDS), 1,4-bismaleimidodiphenylmethane (BMI), pentaerythritol tetrakis(3-mercaptopropionate) (PETMP), and thiol-terminated disulfide-containing polyether (LP) at various feed monomer ratios produced polymer networks containing both DA adduct moieties and disulfide bonds. Fourier transform infrared spectral analysis revealed that the DA and thiol-maleimide reactions occurred for all the cured products. A differential thermal analysis revealed that all the cured products exhibited an endothermal peak due to the retro-DA reaction at 115–124 °C. The tensile moduli and strengths of the cured products increased with increasing DFDS (or DA) and PETMP fractions. The elongations at break increased with increasing LP (or disulfide) fraction. Most of the cured products exhibited self-healing ability by annealing at 60 °C for 24 h, and/or at 120 °C for 1 h followed by additional annealing at 60 °C for 24 h. The cured product with a higher LP (or disulfide) fraction exhibited a better healing ability at 60 °C for 24 h by the disulfide metathesis. Also, the cured product with a higher DFDS fraction exhibited a better healing ability at 120 °C for 1 h and 60 °C for 24 h by the DA/retro-DA reaction.

Proton Conductive Membranes from Covalently Cross‐Linked Poly(Acrylate)/Silica Interpenetrating Networks

Frontispiece: In article number 2000776, Andriy Horechyy, Iryna Yevchuk, Andreas Fery, and co-workers present a series of hybrid proton conducting membranes composed of covalently cross-linked interpenetrating polymeric and silica networks. The effects of monomer composition, sol–gel composition and sol–gel fraction on performance of hybrid proton conducting membranes are investigated and discussed. These novel hybrid membranes hold promise for the application in direct methanol fuel cells (DMFC).

Effects of monomer composition on physical properties and enzymatic hydrolyzability of poly(butylene succinate‐co‐hexamethylene succinate)s

AbstractIn this study, various biodegradable materials, including poly(butylene succinate) (PBS), poly(hexamethylene succinate) (PHS), and poly(butylene succinate‐co‐hexamethylene succinate)s (P[BS‐co‐HS]s) containing different hexamethylene succinate (HS) contents, were prepared. The compositions, thermal properties, mechanical properties, hydrophilicity, and enzymatic hydrolyzability of the materials were investigated by various techniques. The results showed that the composition of the copolyesters was similar to the feeding ratio of the reactants. The melting and crystallization temperatures, thermal stability, and degree of crystallinity of the copolyesters decreased for low HS content and increased for high HS content. P(BS‐co‐HS)s containing 52 mol% HS exhibited low crystallization temperature (Tc), melting temperature (Tm), degree of crystallinity (Xc), and high hydrophilicity, elongation at break and enzymatic hydrolyzability. We also observed that low degree of crystallinity and high crystal defects, hydrophilicity, and high elongation at break could improve the enzymatic hydrolyzability of the materials.

Novel poly (ionic liquid)-based anion exchange membranes for efficient and rapid acid recovery from industrial waste

Owing to the less energy consumption, positive impact on the environment, and prospect of providing clean water resources, anion exchange membranes (AEMs) are promising materials for acid recovery from various industrial wastewater/effluent. Based on the diffusion dialysis process, AEMs selectively allow rapid proton permeation while efficiently retaining metal ions. To enhance the efficiency of the acid recovery process, precise control of macromolecular architecture and chemical composition that enables high hydrophilicity, proton conductivity through the membrane, and ion exchange capacity is required. In this direction, we report on the one-step fabrication of novel poly (ionic liquids)-based AEMs by the free radical polymerization of 1-butyl-3-vinyl imidazolium bromide, acrylic acid, styrene, and acrylonitrile under sunlight. The effect of monomer composition in an AEM matrix on the structural, physicochemical, surface, thermal, and proton conductivity is investigated. The experimentally determined acid dialysis coefficient (UH+) obtained with synthesized poly (ionic liquid) based membranes PILM-1 and PILM-2 were 7.3 ± 2 and 9.2 ± 2 mh−1 at room temperature (25 °C), while separation factors (SF) were 88.9 ± 3 and 50.1 ± 2, respectively. Both the UH+ (>700 times) and SF (>4 times) are significantly values higher compared to the commercial AEM DF-120 (0.009 mh−1 and 18.8 for UH+ and SF, respectively). Thus, this study demonstrates the potential of the prepared AEMs as an alternate to deliver cost-effective, scalable, and rapid acid recovery compared to the currently existing technology.

Effect of Monomer Composition on the Performance of Polymer‐Stabilized Liquid Crystals with Two‐Step Photopolymerization

ABSTRACTPolymer‐stabilized cholesteric liquid crystal (PSCLC) films with broadband reflection based on two‐step photopolymerization are fabricated. Owing to the helical twisting power (HTP) value of the chiral dopant (CD) decreasing with increasing temperature, PSCLC films with broadband reflection are obtained by two‐step polymerization anchoring helical pitch of different length at two different temperature points. The effect of monomer composition on the PSCLC reflection properties before and after polymerization was studied. The results show that the free‐radical monomers with appropriate concentration and cationic monomers with sufficient concentration are vital for the formation of PSCLC films with broadband reflection. In addition, the experiments show that the increase in the functionality and rigidity of the cationic monomer has a positive effect on the broadening of the reflection band. This study can provide guidance and reference for the selection of monomer species and concentration in PSCLC preparation. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1126–1132

Sorption and desorption properties of random copolymer hydrogels of N‐isopropylacrylamide and N‐ethylacrylamide: Effect of monomer composition

ABSTRACTRandom copolymer hydrogels of N‐isopropylacrylamide and N‐ethylacrylamide (NEAM) were prepared using different monomer compositions in 1:1 methanol–water mixtures. The samples were characterized by cononsolvency study in methanol‐water mixtures at various temperatures, swelling properties measurements, scanning electron microscopy. With changing ratio of the monomers in the reaction mixture, the thermal, morphological and swelling properties, varied significantly. The change in the properties with monomer composition variation are interpreted based on the different thermoresponsive characteristics and interactions of gels of N‐isopropylacrylamide and NEAM (homo‐ and copolymer gels) in water and different methanol‐water mixtures, their variable compositions in the synthesis mixtures, and their morphologies. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45176.

Waterborne paints containing nano-sized crystalline domains formed by comb-like polymers

Semicrystalline, waterborne copolymer latexes of stearyl acrylate-co-short chain (meth)acrylate (a mixture of methyl metacrylate, n-butyl acrylate, acrylic acid and acrylamide) have been synthesized by using different 2-step polymerization strategies. The effect of monomer composition and polymerization strategies on the crystallinity and mechanical properties of polymer films were investigated. These semi-crystalline latexes were successfully used as binders in paint formulations and the effect of crystallinity and copolymer microstructure on the mechanical properties (e.g. hardness, scrub resistance, etc.) and hydrophobicity of the paint films was studied.

Antibacterial Activity of Silver Nanoparticle-Loaded Soft Contact Lens Materials: The Effect of Monomer Composition

ABSTRACTPurpose: In the present work, the effect of monomer composition on silver nanoparticles’ (SNPs) binding capacity of hydrogels was investigated and their antibacterial efficacy was evaluated.Materials and methods: Three series of poly-hydroxyethyl methacrylate (HEMA) hydrogels were prepared using methacrylic acid (MAA), methacrylamide (MAAM), and 4-vinylpyridine (4VP) as co-monomers, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. SNPs binding capacity of hydrogels was evaluated in different concentrations (2, 10, and 20 ppm). In vitro antibacterial activity of SNP-loaded hydrogels was studied against Pseudomonas aeruginosa (P. aeruginosa) isolated from patients’ eyes. Then, inhibitory effect of hydrogels in biofilm formation was evaluated in the presence of Staphylococcus epidermidis (S. epidermidis) (DSMZ 3270).Results: Our data indicated that poly(HEMA-co-MAA-co-EGDMA) had superior binding affinity for SNPs in comparison with other hydrogels. All SNP-loaded hydrogels demonstrated excellent antimicrobial effects at all times against P. aeruginosa and S. epidermidis after soaking in 10 and 20 ppm SNP suspensions. Scanning electron microscope (SEM) images revealed excellent inhibitory effect of SNPs against biofilm formation on the surface of the hydrogels.Conclusions: This study indicated the effect of monomer compositions in SNP loading capacity of poly(HEMA) hydrogels and antibacterial efficacy of SNP-loaded hydrogels against P. aeruginosa and S. epidermidis, but further in vivo evaluation is necessary.

Sulfonated polyaniline‐graphene oxide hybrids: Synthesis and effect of monomer composition on the electrochemical signal for direct DNA detection

ABSTRACTA variety of sulfonated polyaniline‐graphene oxide (SPAN‐GNO) nanocomposites based on GNO, aniline (ANI) and m‐aminobenzenesulfonic acid (ABSA) are prepared via changing the mole ratio of ANI to ABSA for the comparison of DNA sensing behavior. Self‐signals of SPAN‐GNO are employed for estimating the effect of preparation conditions [component, monomer composition (mole ratio of ANI to ABSA), and reaction time] on DNA immobilization and hybridization detection. Then, we find herein that the mole ratio of ANI to ABSA plays a lead role over other factors on hybridization efficiency. Meanwhile, the parallel experiments using methylene blue as the classic indicator verifies this conclusion. The results show that, by comparison with other mole ratio SPAN‐GNO nanocomposites‐modified electrodes, the mole ratio (2:3) exhibits the widest dynamic detection range from 1.0 × 10−14 to 1.0 × 10−6 M, as well as the lowest detection limit (3.06 × 10−15 M). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1762–1773

Formation of Hyperbranched Amphiphilic Terpolymers and Unimolecular Micelles in One-Pot Copolymerization

Utilizing self-assembled structures made of small molecular surfactants or linear amphiphilic copolymers to encapsulate hydrophobic chemicals generally faces a dilution challenge due to their critical micelle concentrations. In this study, we designed a one-pot self-condensing vinyl terpolymerization of poly(ethylene glycol) methyl ether methacrylate (PEG) and methacrylic acid (MAA) in n-butyl acetate by using a vinyl-functionalized chain transfer agent (C12-raft). In the presence of hydrophobic epoxiconazole (EP) as a model chemical that can complex with MAA, the resultant amphiphilic hyperbranched terpolymer chains can form unimolecular micelles with EP encapsulated inside. The effects of monomer composition and EP content on the stability of the resultant dispersions in both n-butyl acetate and redispersing water were studied by combining static and dynamic laser light scattering, transmission electron microscopy, and ultraviolet–visible spectroscopy. We found the optimal encapsulation and stabilizatio...

Encapsulation of Curcumin and Curcumin Derivative in Polymeric Nanospheres

Curcumin and curcumin derivative were loaded on biocompatible methyl methacrylate–hydroxyethyl methacrylate copolymeric nanospheres via in situ microemulsion polymerization. The effect of monomer composition and the emulsifier concentration on the entrapment efficiency, the particle size, and zeta potential of the drug loaded-polymeric nanospheres have been studied. The hydrophilic curcumin derivative was loaded with a high value which reached to about (92 ± 0.5%) against (85 ± 0.8%) recorded for the hydrophobic curcumin. In vitro release of curcumin and its derivative loaded in polymeric nanospheres showed slow and a sustained release pattern.

Preparation of porous polyester composites via emulsion templating: Investigation of the morphological, mechanical, and thermal properties

Open porous polyester composites were prepared by the crosslinking of unsaturated polyester resin and divinylbenzene in water‐in‐oil concentrated emulsion templates with the presence of a conventional surface modified montmorillonite nanoclay. Medium and high internal phase emulsions with either 55 or 80 wt% of internal phase were used as templates. The effect of monomer composition, emulsifier concentration, and internal phase amount on the emulsion stability and the morphology of the resulting porous composites were investigated. Moreover, the morphological properties of the resulting composites were determined depending on the amount of nanoclay loading. It was found that the morphological features, namely surface area and cell diameter, were altered dramatically with the amount of nanoclay loading. An important part of the research was focused on the variation of mechanical and thermal properties with the incorporation of nanoclay particles. The mechanical properties were improved both with the nanoclay incorporation and the use of medium internal phase emulsions. However, the used nanoclay did not have a significant effect on the thermal stability of the resulting composites. POLYM. COMPOS., 37:1531–1538, 2016. © 2014 Society of Plastics Engineers

Fast drying and film formation of latex dispersions studied with FTIR spectroscopic imaging.

Drying of thin latex films (∼20 μm) at high drying speeds (of the order of seconds) has been studied by fast chemical imaging. ATR-FTIR spectroscopic imaging combined with a fast "kinetic" mode was used to acquire spectral images without coaddition, enabling the amount of water and homogeneity of the drying film to be studied over time. Drying profiles, constructed from analyzing the water content in each image, show two stages of drying, a fast and a slow region. The formulation of latex dispersions affects the onset of slow drying and the volume fraction of water remaining at the onset of slow drying. In this work, the effect of physical properties, film thickness and glass transition temperature (Tg), were investigated, as well as the effect of monomer composition where two monomoers, 2-ethylhexyl acrylate and n-butyl acrylate, and the amount of hydrophilic comonomer, methyl methacrylate (MMA), were varied. It was found that thicker films produced slower overall drying and that the formulation with a Tg above the minimum film formation temperature did not dry evenly, exhibiting cracking. However, the drying kinetics of high and low Tg films were similar, highlighting the advantage of using a spatially-resolved spectroscopic approach. Formulations containing more MMA dried faster than those with less. This was due to the hydrophilicity of MMA and the increase in Tg of the dispersion from the addition of MMA. Overall, FTIR spectroscopic imaging was shown to be a suitable approach in measuring film drying at high speeds as both chemical changes and chemical distribution could be analyzed over time.

Processing behavior and mechanical properties of autopolymerizing hypoallergenic denture base polymers

ABSTRACTDriven by the phenomenon of increasing irritations and allergic reactions of dental prosthesis carriers preferably due to residual methyl methacrylate monomer in conventional dental materials, autopolymerizing hypoallergenic denture base polymers were prepared as two‐component materials in the shape of paste/paste‐ or powder/liquid systems. The processing behavior of these materials was investigated regarding the processing and solidification times also in dependence on the polymerization catalyst concentration, whereas the whole processing and curing characteristics and the final polymer properties were evaluated by dynamic mechanical analysis in shear mode in the temperature range from −145°C to 200°C. The mechanical properties of the hypoallergenic denture base polymers were validated regarding stiffness (flexural modulus E') and fracture toughness (maximum factor of loading intensity , total work of fracture ) and the effects of monomer composition, kind of resin powder, impact modification by the liquid component, and water immersion on these properties were investigated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41378.

Effect of monomer composition on structural properties of poly(ethylene-co-propylene) nanofiber by Monte Carlo simulation

Structural properties at the bond and molecular level of poly(ethylene-co-atactic propylene) copolymer nanofiber were studied by lattice Monte Carlo simulation. The simulation was performed with a coarse-grained model of these random copolymer chains with the density in the range of 0.753–0.760 g/cm3 at 473 K. The properties of nanofiber were characterized at different monomer fraction. When the ethylene fraction was increased, the relative bead density of nanofibers was increased in the bulk region near the fiber (X) axis and dramatically decreased in the region toward the surface along the radial direction. The interfacial widths of these radial bead density profiles were increased for copolymer with higher ethylene content. End beads of polymer chains became more abundant in the region closer to the vacuum side and the bonds near the surface were more oriented in a parallel direction to the surface with an increase of ethylene content. Molecular size as represented by the radius of gyration (R g ) in the X-component became smaller along the radical direction, while the R g in the Y-Z component was relatively unchanged. There were significant changes in molecular shape (acylindricity) and the size of copolymer (components of the radius of gyration) as a function of ethylene content. Similarly, the largest molecular axis was oriented in a parallel direction to the fiber axis, and changed toward random orientation when the ethylene content was decreased. Open image in new window

5-Fluorouracil delivery from a novel three-dimensional micro-device: in vitro and in vivo evaluation

A novel three-dimensional biodegradable micro-device using microelectromechanical systems technology was developed for implantable controlled drug delivery. In order to evaluate the effect of monomer composition and molecular weight of poly(lactic-co-glycolic acid) (PLGA) on the drug release, three 5-Fluorouracil loaded micro-devices, made of 50/50, 27kDa; 50/50, 40kDa and 75/25 27kDa PLGA, were prepared and characterized by in vitro and in vivo methods. The in vitro drug release from three micro-devices followed zero-order kinetics, and PLGA micro-device with the higher molecular weight and lactide/glycolide ratio tended to a longer sustained release period. The in vivo release results agreed with the in vitro results and drug release in vivo was faster than that in vitro for each of micro-devices. And three micro-devices showed different tumor inhibition effect in the tumor bearing mice. In addition, the SEM and weight loss experiments showed that PLGA micro-devices with lower molecular weight and lactide/glycolide ratio had faster degradation. These data provided the information for the optimization of the novel three-dimensional biodegradable micro-device to obtain more suitable systems for controlled release and to meet release requirements of different drugs.

Synthesis and expansion characteristics of expandable styrene/methyl methacrylate copolymer beads: The effects of monomer composition and cell structure modifying aid

Parts cast of metals such as iron, using expandable polystyrene foams, may have an unacceptable amount of surface defects, such as lustrous carbon. The use of foams made of styrene/methyl methacrylate copolymers can improve the quality of foam molds and metal parts made using such molds. In this work, expandable copolymers were synthesized by suspension copolymerization of styrene and methyl methacrylate in the presence of blowing agents (pentane isomers). When the surrounding temperature was high enough to vaporize the blowing agent and soften the polymer shell, the beads were expanded. The effects of monomer composition and cell structure modifying aid (polyethylene wax) on the particle size, average molecular weight and molecular weight distribution of synthesized copolymer, pentane content and expansion properties (density, residual pentane of pre-expanded particles and cell structure) were investigated. The results showed that monomer composition had a significant effect on the copolymerization kinetic and the copolymer molecular weight. In addition, cell structure, cell size and cell size distribution of the pre-expanded particles were strongly influenced by cell structure modifying aid concentration. The effects of comonomer composition and copolymer particle size on pentane content of expandable particles were also studied.

Study on Structure and Tanning Properties of Copolymer of Resorcinol and 3,5-Dihydroxyl Benzoic Acid

The radical copolymerization of resorcinol (RSC) and 3,5-dihydroxyl benzoic (DHBA) was carried out in water by the initiator of horseradish (HRP)/H2O2. It was discussed that the effects of monomer composition on the properties of the copolymer. The best monomer mass ratio of RSC:DHBA was 60:40 and the shrink temperature can reached to 88.5oC. The tanning result indicated that the copolymer of RSC and DHPA has particularly excellent tanning properties and can be served as leather tannage substitute for chrome tanning materials. And also the mechanism of the HRP initiated copolymerization was proposed. The structure and molecular weight of the copolymer was characterized by Fourier Transform Infrared spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR) and Gel Permeation Chromatography (GPC). The copolymer can be as tannage and retannage in making leather process. The results showed that it has excellent tanning properties and retanning effects.

Study on Synthesis and Properties of Phenols Polymer Syntan Catalyzed by Enzyme

A phenolic copolymer was synthesized from resorcinol (RSC) and 3,5-dihydroxy benzoic acid (DBA) using horseradish peroxidase (HRP)/H2O2 as the radical copolymerization’s initiateor. It was discussed that the effects of monomer composition on the properties of the copolymer. The best molar ratio was 1:1. The structure and properties of the copolymer was characterized by Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (HNMR), Molecular weight (MW) was determined by gel permeation chromatography (GPC). The result shows that the average molecular weight of the copolymer is about 40000. The effect of dosage of HRP on the properties of the copolymer was investigated. And the mechanism of polymerization of RSC and DBA was advanced. The copolymer was used as tanning agent, applied results show that it has excellent retanning properties. It was realized the applicatiom of HRP on the phenols syntan.