Acrylate Mixture Research Articles

Electrostatic Self-Assembly of Composite Nanofiber Yarn.

Electrospinning polymer fibers is a well-understood process primarily resulting in random mats or single strands. More recent systems and methods have produced nanofiber yarns (NFY) for ease of use in textiles. This paper presents a method of NFY manufacture using a simplified dry electrospinning system to produce self-assembling functional NFY capable of conducting electrical charge. The polymer is a mixture of cellulose nanocrystals (CNC), polyvinyl acrylate (PVA) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). When treated with ethylene glycol (EG) to enhance conductivity, fibers touching the collector plate align to the applied electrostatic field and grow by twisting additional nanofiber polymers injected by the jet into the NFY bundle. The longer the electrospinning continues, the longer and more uniformly twisted the NFY becomes. This process has the added benefit of reducing the electric field required for NFY production from >2.43 kV cm−1 to 1.875 kV cm−1.

Investigations on the Processing of Ceramic Filled Inks for 3D InkJet Printing.

3D inkjet printing is moving from a technology of rapid prototyping to rapid manufacturing. The introduction of ultraviolet curable composites filled with functional ceramics could expand the possibilities of this technology. In this work, a simple and scalable process was investigated as a template for the production of inkjet printable functional ceramics. Pyrogenic alumina particles with an average size of 13 nm, 35 nm and 100 nm were used as fillers in an acrylate mixture. The physical coating of the ceramics with 2-[2-(2-methoxyethoxy)ethoxy] acetic acid results in a low-viscosity dispersion with a ceramic content of up to 2 vol%, Newtonian behavior and surface tension within the limits allowed for inkjet printing. The material has sufficient stability for printing tensile specimens. Tensile tests have shown that modulus of elasticity, tensile strength and toughness can be kept constant despite the light scatter caused by the particles. The final production steps could be reduced to grinding and drying of the powders, their resuspension in the organic matrix and inkjet printing. The process can be used in an industrial-scale production of materials for abrasion-resistant components with adapted tribology.

Preparation and properties of ultraviolet/thermal dual-curable polyurethane acrylate

Ultraviolet (UV)/thermal dual-curable polyurethane acrylate (PUA) mixtures were prepared using a PUA oligomer, tripropylene glycol diacrylate (TPGDA), benzoyl peroxide (BPO), 2,4,6-trimethylbenzoyldiphenyl phosphine oxide (TPO), and cobalt isooctanoate. For purposes of comparison, a UV-curable PUA mixture was prepared by mixing the PUA oligomer, TPGDA, and TPO. When placed under a UV lamp (400 W, 50 mW/cm2), the surface drying time of each curable mixture was approximately 2 s. The content of volatiles during UV curing (the intensity of the lamp was 100 mW/cm2) was less than 0.3 wt%, and the content of potential volatiles (the test condition was heating at 110 °C for 1 h after UV curing) was below 1.0 wt%. Compared with the UV-cured sample, the UV/thermal dual-cured sample containing cobalt isooctanoate had more favorable properties, that is: (1) better acid and alkali resistance; and (2) better thermal stability and higher gel content. The temperature at 5 wt% weight loss (T5wt.%) and the gel fraction of the UV-cured sample (the curing condition was 1 min of UV irradiation) were 269.4 °C and 94.6%, respectively. The T5wt.% and the gel fraction of the UV/thermal dual-cured sample (cured at 100 °C for 10 min after 1 min of UV irradiation) were 318.2 °C and 99.8%, respectively. BPO and cobalt isooctanoate had little effect on the surface drying rate of the curable mixtures, and the performance of the cured samples was improved by thermal treatment following irradiation with UV. Considering the dyeing effect of BPO, this system provides a more practical approach to the complete curing of colored UV-curable resins.

Water soluble polymeric photoinitiator for dual-curing of acrylates and methacrylates

A novel water soluble polymeric (photo)initiator is designed for efficient dual curing of mixtures of acrylates and methacrylates. The initiator (PAATX) functionalized with thioxanthone (10 wt %) was synthesized from the aza-Michael addition reaction of a poly(amido amine) (prepared from the reactions of 1,4-diamino butane with N,N’-methylene bisacrylamide) to 9-oxo-9H-thioxanthen-2-yl acrylate. It was used for polymerization of a mixture of 2-hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) diacrylate (PEGDA, Mn = 575 D). The first curing stage is the aza-Michael addition between PEGDA and the amines of PAATX; and the second is visible-light-initiated radical polymerization (PAATX has an absorption maximum in the near UV–vis region, ∼400 nm) of HEMA and remaining acrylates. The kinetics of the curing reactions were investigated using FTIR and photo-DSC. The steady state photolysis results show that PAATX/bis-(4-tert-butylphenyl)-iodonium hexafluorophosphate (Iod) system has the highest photolysis rate which signifies that PAATX forms radicals more efficiently by a photooxidation mechanism. The excited state reactivity has been studied by steady state photolysis, time resolved and steady state fluorescence as well as laser flash photolysis experiments. Remarkably, contrary to the usual behavior of thioxanthone derivatives, the new reported structure exhibits a singlet state reactivity.

Polymeric Biomaterials with Complimentary Role in Joint Endoprosthesis. II. Compositional and morpho-structural analysis

Successfully used in bone surgery for more than 65 years, self-hardening organic cements (CCOs), in particular acrylic cements, are today, the most advanced complementary biomaterials used in articular endoprosthesis. One of the strategies for obtaining of performing anchorage of artificial implants is to develop new acrylic cements with improved physical, chemical and biomechanical characteristics. The aim of this paper was to identify the compositional and morpho-structural changes of acrylic cements induced by the composition of the liquid phase of the material. Such changes influence the potential to generate the physical bonds responsible for fixation and stabilization of endoprosthesis. The samples studied had different compositions due to the mixture of acrylic monomers, methyl methacrylate (MMA) and butyl acrylate (BuA) in the liquid component of cement. The MMA / BuA ratio varied between 1/0 v / v and 1/4 v / v. Changes in the composition and morphology of cement samples have been highlighted by ESCA (Electron Spectroscopy for Chemical Analysis), EDX (Energy-Dispersive X-ray Spectroscopy), IR spectroscopy and SEM images. The obtained data show that minor changes in cement composition can significantly influence morpho-structural characteristics such as pore size and their distribution in the mass of fixing material.

Use of Infrared Spectroscopy for Evaluating the Quality of Fiber Mixing

The application of infrared spectral analysis in the study of fibers is examined. The major absorption intensity peaks of wool and acrylic fiber are determined. An analysis is given for a three-component wool-dyed acrylic fiber-undyed acrylic fiber mixture.

Influence of Al₂O₃ Nanoparticle Addition on a UV Cured Polyacrylate for 3D Inkjet Printing.

The brittleness of acrylic photopolymers, frequently used in 3D Inkjet printing, limits their utilization in structural applications. In this study, a process was developed for the production and characterization of an alumina-enhanced nanocomposite with improved mechanical properties for Inkjet printing. Ceramic nanoparticles with an average primary particle size (APPS) of 16 nm and 31 nm, which was assessed via high-resolution scanning electron microscopy (HRSEM), were functionalized with 3.43 and 5.59 mg/m2 3-(trimethoxysilyl)propyl methacrylate (MPS), respectively, while being ground in a ball mill. The suspensions of the modified fillers in a newly formulated acrylic mixture showed viscosities of 14 and 7 mPa∙s at the printing temperature of 60 °C. Ink-jetting tests were conducted successfully without clogging the printing nozzles. Tensile tests of casted specimens showed an improvement of the tensile strength and elongation at break in composites filled with 31 nm by 10.7% and 74.9%, respectively, relative to the unfilled polymer.

Analysis of Network Structures in Thiol-Ene UV Curing System Using Reworkable Resins.

An analysis of the network structures in thiol-ene UV curing resins was carried out using reworkable resins composed of di(meth)acrylate monomers having tertiary ester linkages. The effect of the functionality of the thiols, the functional ratio of the thiol and ene functions, their conversions and curing atmosphere on the chain lengths was discussed. A mixture of (meth)acrylates, thiol compounds, a photoradical initiator, and a photoacid generator was cured by irradiation at 365 nm. The cured samples were degraded by heating after irradiation at 254 nm. Size exclusion chromatography (SEC) and 1H NMR analyses of the degraded samples were carried out after the methylation. The crosslinking conditions strongly affected the network structures. The degraded samples have molecular weights between 250 and 2700. The molecular weights of the degraded resins increased with the functionality of the thiol compounds. The chain length dependence suggests that thiol compounds with a high functionality have a low reactivity due to steric hindrance. The chain lengths of the degraded networks were nearly proportional to the concentration of the (meth)acrylate monomers. The addition of reactive diluents enhanced the reactivity and increased the chain length.

Fast switchable field-induced optical birefringence in highly transparent polymer-liquid crystal composite

A liquid crystal device with optically isotropic liquid crystal (OILC) phase induced from polymerization-induced phase separation exhibit a fast response time and a proper dark state. Its electro-optic performances are highly influenced by a kind of materials and processing conditions. Here, the effect of materials and phase-separation on the electro-optic performance of OILC device has been investigated by utilizing the acrylate and the thiol-ene monomer mixtures. The optically isotropic phase was analyzed with scattering theory, and it was revealed that a novel polymer network structure of acrylate mixture is free of scattering and yields a higher on-state transmittance, enhanced by ~50%. By tuning the monomer ratio and UV intensity, an excellent transparent film was obtained and, in addition, the response time was improved by ~40%. The excellent black state and its flexibility can be applied to flexible liquid crystal photonic and display devices.

IMMEDIATE HYPERSENSITIVITY TO A DENTAL APPLIANCE CONTAINING NICKEL AND METHYL METHACRYLATE

Introduction Type IV delayed hypersensitivity reactions causing allergic contact dermatitis secondary to nickel and acrylates are commonly reported. Immediate hypersensitivity from both of these materials is a rare presentation that should be taken into consideration from allergic reactions to dental appliances. Case Description A 50-year old man with obstructive sleep apnea was referred by his dentist after an acute allergic reaction resulted in an emergency room (ER) visit after wearing a dental appliance for the first time. The patient describes symptoms began within 2 hours of wearing a mandibular advancement oral device. He developed redness and burning sensation in his legs, angioedema involving his face and tongue, metallic taste, and palpitations. In the ER, he was treated with epinephrine, as well as diphenhydramine, famotidine and methylprednisolone. His symptoms resolved within minutes of epinephrine administration. Upon further investigation, it was determined that the mandibular advancement device contained both alloy containing nickel and a mixture of acrylates. Both skin prick testing and patch testing are scheduled to be performed to determine either immediate or delayed hypersensitivity to nickel and acrylates. Discussion While nickel and acrylates have previously been reported to cause delayed hypersensitivity reactions manifesting as allergic contact dermatitis, there are only a few published cases of type I hypersensitivity to nickel allergy manifesting as urticaria or angioedema. This case is a rare example of either nickel or acrylate potentially causing an immediate hypersensitivity reaction and should be further investigated as a cause of angioedema after initial use of a dental appliance.

In situ formation and immobilization of silver nanoparticles using thermo-responsive microgel particles and their cytotoxicity evaluation

In this study, a simple environmentally greener “in situ” chemical synthesis has been developed to prepare silver nanoparticles (Ag NPs) from chemically reduced AgNO3 in an aqueous media of thermo-responsive microgel, using glucose as a reducing agent and by adopting a microwave irradiation technique. The thermo-responsive microgel poly-N-isopropylacrylamide-co-2-hydroxyethyl acrylate, poly (NIPAM-co-HEA) 200 nm in size was prepared by surfactant free emulsion polymerisation of a selected mixture of N-isopropylacrylamide, methylene-bis-acrylamide and 2-hydroxyethyl acrylate. This microgel acts as a mere support to immobilize Ag NPs. The formation of Ag NPs and the thermo-responsive properties of the mixture were studied using UV–visible Spectroscopy. Their structures were characterised by FE-SEM and TEM. The Ag NPs prepared by this approach appear to be monodispersed with sizes which are <15 nm. Excellent biocompatibility, cell viability and environmentally responsive properties suggested that as-prepared composite particles are ideal candidate for antibacterial, biosensors and drug delivery applications.

Silk fibres grafted with 2-hydroxyethyl methacrylate (HEMA) and 4-hydroxybutyl acrylate (HBA) for biomedical applications

Silk fibroin may be chemically modified by grafting, with the purpose of improving its properties according to the desired function. In this study, silk fabrics from Bombyx mori silk fibres were grafted with 2-hydroxyethyl methacrylate (HEMA), as well as a binary mixture of HEMA and 4-hydroxybutyl acrylate (HBA). The samples were then electrospun from trifluoroacetic acid and treated with aqueous methanol. The% weight gains ascribable to HEMA and HBA were successfully determined through Raman spectroscopy. PolyHEMA made the fibres more hydrophilic and hindered crystallization into β-sheet only upon electrospinning and treatment with aqueous methanol; the presence of the HBA component in the grafting mixture did not further decrease the ability of silk fibroin to rearrange into β-sheet, due to its low contents (below 5%) under the used experimental conditions. Fibrillation partially occurred in the grafted fabrics; the electrospun samples maintained their nanostructured morphology. The surface of the substrates under investigation was compatible with cell attachment and growth, which were higher for the nanofibres. Cell adhesion and proliferation may be modulated by varying the surface chemistry and topography of the fabrics; grafting improved the surface properties of silk fibroin for enhanced functional performance in view of biomedical applications.

Hydrophobically modified polyacrylates (hmPAAs) with long alkyl chains – Self-assembly in aqueous solution

Hydrophobically modified polyacrylates (hmPAAs) obtained by Atomic Transfer Radical Copolymerisation (ATRP) of mixtures of different alkyl acrylates and t-butyl acrylate and subsequent hydrolysis of the t-butyl acrylate to polyacrylic acid (PAA), were studied with respect to their aggregation behaviour in aqueous solution. The hydrophobic modifications were long alkyl chains that were varied systematically from dodecyl to stearyl, thereby expecting a strong propensity for hydrophobic aggregation. Their structure in aqueous solution was investigated comprehensively by small-angle neutron scattering (SANS) and complemented by dynamic light scattering (DLS) experiments. In these random copolymers the degree of amphiphilicity and hydrophobicity was varied by the percentage of alkyl chains and pH. Due to the length of the alkyl chain all these copolymers have a tendency for microphase separation, but this tendency and the structure of the formed hydrophobic domains depend in a systematic fashion on the precise molecular composition. The domain size scales with the length of the hydrophobic alkyl modification and, for chains of C16 and longer, there is apparently a tendency for elongation. Another interesting observation is that for 20 mol% hydrophobic modification rather self-contained and isolated hydrophobic micellar domains are formed. In contrast, the copolymers with 10 mol% alkyl modification contain interconnected hydrophobic domains as evidenced from the low-q scattering seen in SANS and confirmed by DLS observations. This tendency is further enhanced when fully charging the copolymers. In summary, the molecular design of such random amphiphilic copolymers allows in a nice way to control the aggregation state in solution.

Combining stereolithography and replica molding: On the way to superhydrophobic polymeric devices for photovoltaics

A strategy combining stereolithography (SL) and soft-lithography for the straightforward fabrication of superhydrophobic bulk devices is reported. Microtextured masters are rapidly prototyped by SL and passivated with a perfluorosilane. Such surface treatment enables the faultless fabrication of negative microstructured polydimethylsiloxane molds ultimately utilized to obtain bulk polymeric micropatterned structures by replica molding. As illustrative proof of concept, this approach is employed in the field of photovoltaics to realize the first example of superhydrophobic luminescent solar concentrators (LSCs) showing superior self-cleaning properties. Following our strategy, a new dye-doped acrylate mixture is developed and optimized to ensure complete wetting of the hollow microstructures present on the mold. By judiciously tailoring the photoinitiator concentration and by implementing a tailored double-step UV-irradiation process, complete UV-photopolymerization is achieved despite the significant thickness of the target samples. The high fidelity replication of the original SL-printed features on the daughter replicas as well as their super water-repellency are successfully demonstrated. The performance of the resulting superhydrophobic LSCs is investigated at varying device dimensions and found to be comparable with state-of-the-art systems. This study demonstrates the potential of high-resolution SL-printing in combination with replication techniques as a versatile tool to reproducibly fabricate microstructured superhydrophobic polymeric bulk devices in a straightforward fashion.

Preparation and characterisation of acrylic–polyurethane-based waterborne anticorrosion coating on galvanised steel

Four water-based organic composite coating solutions were prepared and applied on galvanised sheet samples producing a transparent film of about 5-µm thickness. Their corrosion performances were examined by Tafel polarisation, EIS, salt spray and cyclic corrosion tests. The primary coating formulation contained an acrylic emulsion and polyurethane dispersion mixture together with additives. The corrosion resistance properties of the primary formulation were enhanced by adding nano-ZnO particles, and further improved by adding corrosion inhibitors such as zinc phosphate and sodium phosphate. The final formulation on galvanised samples showed 720 h of salt spray resistance and 90 cycles of cyclic corrosion resistance, SAE J2334. The Tafel and EIS studies indicate that the coating possesses barrier protection properties. The electrolyte penetrates through the coating within 24 h but progress of corrosion depends upon the coating adhesion and its compactness, that is improved significantly by adding nano-ZnO and corrosion inhibitor to the coating formulation.

Development and characterization of adjustable refractive index scattering epoxy acrylate polymer layers

Several polymer films for improved optical properties in optoelectronic devices are presented. In such optical applications, it is sometimes important to have a film with an adjusted refractive index, scattering properties, and a low surface roughness. These diffusing films can be used to increase the efficiency of optoelectronic components, such as organic light-emitting diodes. Three different epoxy acrylate mixtures containing Syntholux 291 EA, bisphenol A glycerolate dimethacrylate, and Sartomer SR 348 L are characterized and optimized with different additives. The adjustable refractive index of the material is achieved by chemical doping using 9-vinylcarbazole. Titanium nanoparticles in the mixtures generate light scattering and increase the refractive index additionally. A high-power stirrer is used to mix and disperse all chemical substances together to a homogenous mixture. The viscosity behavior of the mixtures is an important property for the selection of the production method and, therefore, the viscosity measurement results are presented. After the mixing, the monomer mixture is applied on glass substrates by screen printing. To initiate polymerization, the produced films are irradiated for 10 min with ultraviolet radiation and heat. Transmission measurements of the polymer matrix and roughness measurements complement the characterization.

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.

Design of Particle Morphology for Redox‐Initiated Spray Polymerization of Acrylic Acid and Sodium Acrylate by Investigating Levitated Single Droplet

SummaryIn order to optimize the spray polymerization of acrylic acid and sodium acrylate, an acoustic levitator was efficiently utilized to model the system. The acoustic levitator simulates the fall of a droplet in a spray tower. A particle morphology map of SEM images was designed to reproduce certain particle surfaces by varying the drying conditions and the initiator system, which were adjusted for a polymerization. Thus, a droplet of an aqueous monomer mixture of acrylic acid and sodium acrylate was positioned in an acoustic levitator and the polymerizations were initiated with two redox systems, one with ammonium peroxodisulfate and the other one with potassium peroxodisulfate, and were compared to each other. The redox system can beneficially initiate the polymerization at low temperature (&gt;40 °C). By means of a camera and a light source, shadowgraphy was used to analyze the droplet drying kinetics.

The Effect of Silica and Prepolymer Nanoparticles on the Mechanical Properties of Denture Base Acrylic Resin.

To evaluate how hydrophobic nanoparticle silica and prepolymer affect the flexural strength, surface hardness, surface roughness, and resilience of a denture base acrylic resin. A total of 40 denture base acrylic resin specimens with dimensions 65×10×3 mm3 were fabricated in this study. Specimens were divided into five experimental groups (n = 8) according to surface-treated silica and prepolymer concentration incorporated into the acrylic resin (weight %) prior to polymerization: G1 acted as control, no fillers were used in this group. G2: 1 wt% 12 nm silica nanoparticles; G3: 5 wt% 12 nm silica nanoparticles; G4: 1 wt% 12 nm prepolymer nanoparticles; G5: 5 wt% 12 nm prepolymer nanoparticles were added into the acrylic mixture. Acrylic specimens were polymerized according to the manufacturer's instructions. Three-point bending test was performed to evaluate the flexural strength and the resilience of the specimens. Then, a digital profilometer was used to determine the surface roughness of the specimens. Surface hardness was conducted by a digital Shore D hardness testing machine. Surface analysis of one specimen in each group was performed with a scanning electron microscopy (SEM) to observe the fracture surfaces of specimens. ANOVA and Tukey tests were used for the statistical analysis (p<0.05). Statistical analysis revealed significant differences among the groups. All groups showed poor flexural strength as compared with the control (p<0.05). Regarding resilience, silica 5% showed the highest value whereas silica 1% showed the lowest value. Regarding Shore D hardness, silica 1% had the lowest hardness whereas polymer addition did not significantly influence the hardness of the acrylic resin (p<0.05). Furthermore, silica 1% presented the highest roughness as compared with the other groups (p<0.05). SEM images indicated some porosity and voids on fracture surfaces. Both the silica and prepolymer incorporation into acrylic resin adversely affected the flexural strength of the acrylic resin compared to control group. In all concentrations, prepolymer incorporation resulted in increased flexural strength of acrylic resins compared to silica addition. The greater concentrations of the fillers resulted in increased mechanical properties of the acrylic resin.

Synthesis of Covalently Cross-Linked Colloidosomes from Peroxidized Pickering Emulsions

A new approach to the formation of cross-linked colloidosomes was developed on the basis of Pickering emulsions that were stabilized exclusively by peroxidized colloidal particles. Free radical polymerization and a soft template technique were used to convert droplets of a Pickering emulsion into colloidosomes. The peroxidized latex particles were synthesized in the emulsion polymerization process using amphiphilic polyperoxide copolymers poly(2-tert-butylperoxy-2-methyl-5-hexen-3-ine-co-maleic acid) (PM-1-MAc) or poly[N-(tert-butylperoxymethyl)acrylamide]-co-maleic acid (PM-2-MAc), which were applied as both initiators and surfactants (inisurfs). The polymerization in the presence of the inisurfs results in latexes with a controllable amount of peroxide and carboxyl groups at the particle surface. Peroxidized polystyrene latex particles with a covalently grafted layer of inisurf PM-1-MAc or PM-2-MAc were used as Pickering stabilizers to form Pickering emulsions. A mixture of styrene and/or butyl acrylate with divinylbenzene and hexadecane was applied as a template for the synthesis of colloidosomes. Peroxidized latex particles located at the interface are involved in the radical reactions of colloidosomes formation. As a result, covalently cross-linked colloidosomes were obtained. It was demonstrated that the structure of the synthesized (using peroxidized latex particles) colloidosomes depends on the amount of functional groups and pH during the synthesis. Therefore, the size and morphology of colloidosomes can be controlled by latex particle surface properties.