Acrylic System Research Articles

The electro-optical characteristics and applicability evaluation of a photo-induced vertical alignment negative-type liquid crystal/photo-curable acrylic pre-polymer mixture system mixed with chiral smectic A phase liquid crystal

In this study, we have investigated newly synthesised chiral smectic A (SmA*) liquid crystals (LCs) with a lactic acid structure with polarised optical microscopy (POM). We started cooling from the clear point until a SmA* phase emerged as the temperature dropped to the range 55.7–88.6°C. At this point, the alignment of the LC molecules resulted in a homeotropic texture. To take advantage of this characteristic, we then mixed the SmA* LC into a negative dielectric anisotropy nematic-type liquid crystal (NLC)/photo-curable acrylic pre-polymer mixture system (the NLC mixture system) with photo-induced vertical alignment, to realise the vertical alignment effect among the NLC molecules. This multi-component LC mixture system gave rise to a special, unknown twist grain boundary AX (TGB AX *) phase with rather broad temperature range, which maintained its helix structure even after crystallisation. In addition, we also utilised the electrical field induced molecular tilt effect (the electroclinic effect) within the SmA* LC to improve the response time of the LC device and gray-scale capability of the NLC mixture system. We further observed this multi-component LC mixture system after ultraviolet light irradiation treatment with POM, to investigate the alignment of the LC molecules, device display and electro-optical properties.

A New Liposomal-Drug-in-Adhesive Patch for Transdermal Delivery of Sodium Diclofenac

Liposomes are known to have considerable potential as drug carriers such as liposomal suspension, freeze dried and cream-based systems among many other liposomal formulations. In this study a new drug-in-adhesive patch was fabricated using liposome-based nanocarrier. Transfersomes as ultra-deformable liposomes are based on phosphatidylcholin 95% (phospholipon 90G) and phosphatidylcholin 50% (phosal 50PG) were prepared and further optimized in a final acrylic patch system for effective adhesion. The prepared liposomes were added to an acrylic adhesive to obtain a new hybrid transdermal patch termed as “lipo-drug-in-adhesive” patch system. The sodium diclofenac was selected as a model drug and the permeation of the drug across rat skin was evaluated (P > 0.05), using the lipo-drug-in-adhesive patch system with various percentages of transfersomes (4% - 8%w/w) and constant concentration of the drug (2% w/w). The peel strength and tack value of samples were also examined and quantified. The maximum flux of sodium diclofenac was observed in samples containing 8% (w/w) phosphatidylcholin 50%. The peel strength and tack value in samples containing phosphatidylcholin 50% were lower than those samples containing phosphatidylcholin 95%. It was observed that with increased amount of liposome in drug-in-adhesive patch system, the rate of skin permeation of the drug was also increased. It can be concluded that the developed lipo-drug-in-adhesive patch system enhances the drug release potential of transdermal delivering systems.

Hyperbranched alternating block copolymers using thiol–yne chemistry: materials with tuneable properties

Alternating-block hyperbranched polymers were synthesized using the highly versatile thiol-yne reaction. Dimethyl acrylamide-styrene and tert-butyl acrylate-styrene polymers were prepared, with subsequent hydrolysis of the tert-butyl ester to acrylic acid. The dimethyl acrylamide-styrene hyperbranched polymers self-assembled into large aggregates, as did the acrylic acid-styrene system at low pH. However, high pH triggers the formation of very well defined small particles in the latter system.

Biobased-Chemical Toner Prepared from Palm oil Derivatives

One of major challenge in bio-toner making was how to increase the amount of bio content. Palm oil based alkyd polyester was synthesized through step growth polymerization, mixed with styrene monomer (Sty) and butyl-acrylate (Ac) as co-monomer to produce the hybrid latex. Different levels of alkyd polyester incorporation were studied. Flocculation process was carried out using the hybrid latex with different alkyd resin percentage mixed with other additives like coagulant, wax, charge control agent, and pigment to produce bio-chemical toner, Palmotone™ CPT. The increasing intensity of OH stretching peak from pure Sty-Ac latex (standard) to highest alkyd polyester containing latex showed alkyd resin was well incorporated into styrene acrylic system. Besides, bio-based content analysis (ASTM D6866) revealed that percentage of renewable carbon to total carbon is increasing when alkyd polyester level increased. In addition, it was proven in this paper that the desirable properties in chemical toners are still achievable with the usage of palm oil based alkyd polyester. Furthermore, incorporation of bio-based materials will create a great versatility and hence serves various requirements in chemical toner applications, covering wide range of printers and copiers in the market. Higher level of incorporation is still under further study.

Delayed release film coating applications on oral solid dosage forms of proton pump inhibitors: case studies

Background: Formulation of proton pump inhibitors (PPIs) into oral solid dosage forms is challenging because the drug molecules are acid-labile. The aim of this study is to evaluate different formulation strategies (monolithic and multiparticulates) for three PPI drugs, that is, rabeprazole sodium, lansoprazole, and esomeprazole magnesium, using delayed release film coating applications. Method: The core tablets of rabeprazole sodium were prepared using organic wet granulation method. Multiparticulates of lansoprazole and esomeprazole magnesium were prepared through drug layering of sugar spheres, using powder layering and suspension layering methods, respectively. Tablets and drug-layered multiparticulates were seal-coated, followed by delayed release film coating application, using Acryl-EZE®, aqueous acrylic enteric system. Multiparticulates were then filled into capsules. The final dosage forms were evaluated for physical properties, as well as in vitro dissolution testing in both compendial acid phase, 0.1N HCl (pH 1.2), and intermediate pH, acetate buffer (pH 4.5), followed by phosphate buffer, pH 6.8. The stability of the delayed release dosage forms was evaluated upon storage in accelerated conditions [40°C/75% relative humidity] for 3 months. Results: All dosage forms demonstrated excellent enteric protection in the acid phase, followed by rapid release in their respective buffer media. Moreover, the delayed release dosage forms remained stable under accelerated stability conditions for 3 months. Conclusions: Results showed that Acryl-EZE enteric coating systems provide excellent performance in both media (0.1N HCl and acetate buffer pH 4.5) for monolithic and multiparticulate dosage forms.

Adhesive retention of sodium hyaluronate ophthalmic viscosurgical devices in an acrylic tube model and in porcine-eye corneal endothelium with different irrigation rates

To evaluate the influence of irrigation rates on the adhesive retention of sodium hyaluronate ophthalmic viscosurgical devices (OVDs) by observation in an acrylic tube system designed to model the epithelial wall and in a porcine-eye experiment. Kohseichuo Hospital, Tokyo, Japan. Commercial sodium hyaluronate OVDs differing in molecular weight were visualized with fluorescein powder. Their adhesive and kinetic characteristics at 2 irrigation rates were visually observed in the acrylic tube model and in a porcine eye under phacoemulsification and aspiration. In the acrylic tube model, the mean retention time of the low-molecular-weight sodium hyaluronate increased from 2.3 seconds under 78 mL/min irrigation to 27.9 seconds under 45 mL/min irrigation. In the porcine eye, phacoemulsification retention of the same OVD on the corneal endothelial cells was also longer under the low irrigation rate of a 2.2 mm incision than under the higher rate of a 3.5 mm incision. The stable retention of low-molecular-weight sodium hyaluronate in the acrylic tube model at the low irrigation rate corresponded closely with that observed in the porcine eye. This indicates that low-molecular-weight sodium hyaluronate with the low irrigation rates used in procedures such as microincision cataract surgery may effectively protect corneal endothelial cells against surgical risks.

Characterization of coating systems by scanning acoustic microscopy: Debonding, blistering and surface topology

Scanning acoustic microscopy (SAM) has been applied to different commercial coating systems on steel substrates in order to evaluate the potential of the method for fast non-destructive testing during material development: the focus was on defect detection after and during accelerated weathering and corrosion tests. The possibility of detecting hidden defects (e.g., blisters) in an early stage of weathering or corrosion tests has been evaluated for different commercial coating systems. Using different scanning modes 2K polyurethane systems (solvent- and water-borne) have been examined by SAM. Debonding at the polymer/substrate interface and the interface between base coat and top coat has been studied in samples after simulated weathering. The time dependence of “blister nucleation and growth” has been studied during a salt spray test. Furthermore, the surface topography has been investigated for UV-cured acrylic systems with and without antioxidants after simulated weathering.

Effect of functionalised core–shell microgels prepared by emulsion polymerisation on acrylic coatings properties

The influence of hydroxyl-functionalised acrylic core–shell microgels incorporated into a solvent-borne acrylic binder system on the properties of coatings is described in this paper. Our approach has been to show the usefulness of prepared functionalised microgels as coating modifiers. This subject was shown to be connected with the selection of an appropriate solvent with good affinity for microgels and the film-forming polymer. Therefore the swelling behaviour of microgels in selected solvents as a function of microgel composition is discussed as well. The structured microgels were prepared by first making an aqueous emulsion via the semi-batch emulsion copolymerisation, then dehydrating the system by air drying followed by grinding in a mill. The resulting agglomerates of spherical microgel particles were dispersed in convenient organic solvent media and after that added to the thermosetting solvent-borne acrylic binder system. It was shown that the application of core–shell microgels did not affect the surface appearance and transparency of coatings. Moreover, the presence of microgel network precursors improved corrosion resistance of coatings.

Intermittent curing and its effect on pulsed laser-induced photopolymerization

Different intermittent curing methods were conducted for pulsed laser induced photopolymerization reactions in a TMPTA acrylic system. Two methods of curing were compared, named grouped pulses impingement (GPI) and consecutively pulsed curing (CPC), respectively, in which the total number of the curing pulses were kept same. In GPI, a prominent light diffraction effect was observed in the post curing process, but was absent in the CPC procedure. A condensed but limited sized core of polymeric structure was the cause of the light diffraction. The amount of inhomogeneity in the refractive index for the core was about 90% of the cured background. Simulations based on Fresnel diffraction theory were performed, and the result was in good agreement with the experimental observations.

Development of Enteric Coated Flurbiprofen Tablets using Opadry/acryl-eze System—A Technical Note

Tablet coating is perhaps one of the oldest pharmaceutical processes still in existence (1). It offers many benefits namely: improving the aesthetic qualities of the dosage form, masking unpleasant odour or taste, easing ingestion, improving product stability and modifying the release characteristics of the drug. It is widely used in enteric coating, controlled release system and osmotic pump systems (2). Enteric coated dosage forms are designed to resist the destructive action of the gastric fluid and to disintegrate in the higher pH environment of the intestinal fluid. Polymer for enteric coating can be applied to solid dosage forms (i.e. granules, pellets, or tablets) from aqueous solutions of alkali salts, or organic solvent solutions. The most commonly used pH-sensitive enteric coating polymers today include: cellulose acetate phthalate (CAP), cellulose acetate trimellitate (CAT), hydroxypropyl methyl cellulose phthalate (HPMCP) and methacrylic acid copolymers (3). In recent years, acrylic copolymers have evolved as the most preferred materials for designing enteric coating formulations in terms of performance and global acceptability (1). Aqueous enteric film coatings have been used widely in recent years. Many of these systems are pseudolatex dispersions of polymers such as CAP, latex dispersions of methacrylic acid copolymers and aqueous solutions of alkali salts (4).The advantages of an aqueous based coating system have been recognized. This is derived from the drawbacks of organic solvents including pollution, explosion hazards, and solvent toxicity. Especially there are risks for operators (5). Almost all nonsteroidal anti-inflammatory drugs irritate gastric mucosa and enhance ulceration by blocking protective action of the prostaglandins on gastric mucosa, causing ulcer formation not only in stomach but also in lower part of oesophagus and in duodenum too (6). The most important side effects of flurbiprofen include peptic ulceration, hemorrhage and perforation (7).The aim of current investigation was to develop an enteric coated flurbiprofen tablet formulation to minimize the gastric intolerance caused by flurbiprofen on long term use and to improve patient compliance by utilizing Acryl-Eze. Acryl-Eze is an optimized, one-step, pigmented, aqueous acrylic system for the application of an enteric film coating for oral solid dosage forms. Acryl-Eze combines the benefits and performance of a globally accepted enteric polymer (Eudragit® L100-55) with a fully formulated coating system, providing significant time savings in both development and production. Acryl-Eze has further been optimized for either tablet or multiparticulate applications (8). Eudragit® L100-55 is a copolymer of methacrylic acid and ethyl acrylate (1:1 ratio) which meets the USP definition for Methacrylic Acid Copolymer Type C. L100-55 is a re-dispersible powder produced by spray drying Eudragit® L30-D. Film coatings prepared from such dispersions are resistant to gastric juice but readily dissolve at a pH above 5.5 (9). EudragitL100-55 has been used as a coating polymer in several studies (10,11,12).

Syntheses and Photoreaction Properties of Novel Photopolymer having Styryl Cross Linker

Novel photopolymer having styryl cross linker was synthesized by simple method addition of Vinyl Benzyl Glycidyl Ether (VBGE). Properties of this novel photopolymers were evaluated. As a result, same or higher sensitivity was obtained in comparison with conventional acrylic system by using Oxime compound as photo-initiator. When Acrylic multi-functional monomer was added, styryl cross linker polymers showed high sensitivity without selectivity of initiators. Styryl cross linker polymer is expected as a new excellent material in electrical properties and chemical resistance.

Removal of organic solvents for the purpose of manufacturing of solvent-free pressure-sensitive adhesives

Removal of organic solvents for the purpose of manufacturing of solvent-free pressure-sensitive adhesives The present report reports on the process of the removal of organic solvents in the polymerisation reactor, thin-layer evaporator, and twin-screw extruder for the production of the solvent-free acrylic pressure-sensitive adhesives (PSA). New applications and technical specifications stimulate the continuous development of new methods of manufacturing of non-solvent self-adhesives. The new synthesis of 100% acrylic systems includes solvent polymerisation and finally a removal of volatile organic compounds in a special extruder, polymerisation vessel or an industrial evaporator. The removal process requires controlling such relevant parameters as temperature, pressure and volatile organic compounds concentration.

Preparation of thermo-responsive acrylic hydrogels useful for the application in transdermal drug delivery systems

In this research, hydrogel membranes mainly composed of three kinds of latex particles within carboxymethyl cellulose (CMC) matrix were prepared for the purpose of transdermal drug release. All three latex particles were acrylic systems and synthesized by emulsion polymerization with the addition of an initiator, potassium persulfate, and a crosslinking agent, methylene bisacrylamide. Among them, poly(acrylic acid- co-sodium acrylate) copolymer was applied to increase the swelling ability of hydrogel membrane. Degree of neutralization or the amount of added crosslinking agent was changed to give the optimum properties endowed to the membrane. Poly(acrylic acid- co-2-ethylhexyl acrylate) copolymer latex was used to provide the adhesive ability for the membrane. Finally, to give a thermo-responsive behavior in swelling, poly( N-isopropyl acrylamide) latex and its copolymers were synthesized by polymerization of N-isopropyl acrylamide with different amounts of acrylic acid, in which lower critical solution temperature (LCST) could be modulated. Besides blending these microgel particles with CMC and several other compounds such as tartaric acid and PAA oligomer used to adjust pH value of doping solution, aluminum ion (Al 3+) was applied to give ionic interaction with carboxylate groups distributed in all three latex particles, thus giving interconnected interactions among all microgel particles and in turn a good membrane formability. Morphology, structures and swelling capability of prepared hydrogel membranes were then examined. Caffeine, used as the model drug, was incorporated into membranes and the drug release behavior at different temperatures was evaluated. These prepared hydrogel membranes have potential in the application of transdermal drug delivery system.

Particle Nucleation in High Solids Miniemulsion Polymerization

The nucleation mechanisms in high solids content semicontinuous miniemulsion polymerization was investigated using as case study a silicone−acrylic system. Batch polymerization of the miniemulsion used as initial charge of the reactor was studied. Semicontinuous processes using both miniemulsion feeding and neat monomer feeding were considered. Strategies to maximize the extent of droplet nucleation and to minimize the formation of polymer particles by homogeneous nucleation were discussed.

Detection of Negative Molecular Ions in Acrylic Acid Plasma: Some Implications for Polymerization Mechanisms

There is much scientific and commercial interest in plasma polymers to modify surface chemistry. To date, only neutral and positively charged species have been detected in the commonly applied acrylic acid plasma. Using time-averaged negative ion mass spectrometry, we demonstrate that large, negatively charged species exist in the plasma, contrary to previous studies that detected only neutral and positive species. We briefly outline how negative molecules may contribute to the deposition of plasma polymer in the acrylic acid system.

UV-crosslinked acrylic pressure-sensitive adhesive systems containing unsaturated ethers

A new class of acrylic pressure-sensitive adhesives (PSA), containing oxirane groups [formula (VII)], were developed. PSA systems obtained from butyl acrylate, glycidyl methacrylate and acrylic acid were modified with selected unsaturated allyl, vinyl or 1-propenyl ethers [formulas (I)-(VI)] in amounts of 1.0 to 5.0 wt. %. Then they were cured (using UV lamp) in the presence of 1.0 wt. % of cationic photoinitiator Irganocure 261 at room temperature and air atmosphere for 3 min. The tack, adhesion to glass and cohesion values of the cured PSA samples were measured. The effects of the type and concentration of unsaturated ether monomers used on these properties were evaluated. It was found that vinyl and 1-propenyl ethers were the most UV reactive crosslinking monomers while allyl ethers deteriorated PSA properties. The most advantageous values of adhesion, cohesion and tack were obtained for the samples containing 2 wt. % of vinyl or 1-propenyl ether. The results of investigations showed also that increase in crosslinking time, under UV radiation, caused faster increase in cohesion of the samples modified with vinyl ethers in comparison with those modified with 1-propenyl ones.

Studies on corrosion resistant properties of inhibitive primed IPN coating systems in comparison with epoxy-PU systems

Though blending polymers to obtain high performance materials is an old practice, the new trend in such an approach is the emergence of interpenetrating polymer networks (IPNs) as binders for protective coatings with improved properties. In this study, one ambient curing IPN-type polymer alloy developed out of epoxy and acrylic polyurethane systems as a high performing binder was formulated into paints and evaluated in comparison with the currently used conventional epoxy polyamide and polyurethane systems. A three-coat system consisting of a zinc phosphate primer, a micaceous iron oxide (MIO) undercoat, and a topcoat was formulated out of the IPN along with a similar system of epoxy primer, epoxy undercoat, and a PU topcoat. A two-coat system of the same primer with an IPN clear topcoat and a similar system with epoxy has also been studied. All the systems were studied under accelerated laboratory tests and field tests at a corrosive location. The results are reported and conclusions are drawn in this article.

Application of 2-hydroxyethyl methacrylate polymers in controlled release of 5-aminosalicylic acid as a colon-specific drug

Acrylic type polymeric systems having degradable ester bonds linked to 5-aminosalicylic acid were synthesized and evaluated as materials for drug delivery. 5-Aminosalicylic acid, as an important drug in the treatment of inflammatory bowel diseases, was linked to 2-hydroxyethyl methacrylate by activated ester methodology in two-step and one-pot procedures to obtain methacryloyloxyethyl 5-amino salicylate. The resulting methacrylic derivative of 5-aminosalicylic acid was copolymerized with methacrylamide, 2-hydroxyethyl methacrylate and methyl methacrylate (in 1:3 mole ratio) by free radical polymerization method in N,N-dimethylformamide solution, utilizing α,ά-azoisobutyronitrile as initiator at the temperature range of 65–70 °C. The obtained polymers were characterized by FT-IR, 1H NMR, 13C NMR and elemental analysis. The average molecular weights of the polymers bearing drug units as side substituents of the acrylic backbone were determined by gel permeation chromatography and their polydispersity indices resulted in the range of 1.6–1.8. Release studies of 5-aminosalicylic acid were performed into dialysis bags by hydrolysis in buffered solutions (pH 1, 7 and 8) at 37 °C. Detection of hydrolysis by UV spectroscopy at selected intervals showed that the drug can be released by selective hydrolysis of the ester bond at the side of drug moiety. The release profiles indicated that the hydrolytic behavior of polymeric prodrugs is strongly based on the polymer hydrophilicity and the pH value of the hydrolysis solution. The results suggest that these systems could be useful for preparation of a controlled release formulation of 5-aminosalicylic acid in colon.

Synthesis and cross-linking of acrylic PSA systems

Since their introduction half a century ago, pressure-sensitive acrylic adhesives have been successfully applied in many fields. They are used in self-adhesive tapes, labels and protective films, as well as in dermal dosage systems for pharmaceutical applications, in biomedical electrodes, and in the assembly of automotive parts, toys, electronic circuits and keyboards. Three properties which are useful in characterizing the nature of pressure-sensitive adhesives (PSAs) are tack, adhesion and cohesion. They are determined, to a large degree, by the kind of monomers, solvent nature, initiator type and amount, molecular weight of acrylic co-polymer, polymerization method, and especially by the type and quantity of the cross-linking agent added to the PSA. There are internal and external cross-linking agents. UV technology is well established in the market and allows the production of a wide range of UV-cross-linkable pressure-sensitive adhesives with interesting features.

Effects of Pigment Type and Dispersion on Photodegradation of Epoxy and Acrylic Urethane Films

ABSTRACTThe effects of surface treatment, particle size, and concentration of titanium dioxide (TiO2) and its dispersion on the photodegradation of two resin systems, epoxy and acrylic urethane, were examined. A suite of techniques, including laser scanning confocal microscopy (LSCM) and attenuated total reflectance -Fourier transform infrared spectroscopy (ATR-FTIR), was used to follow the degradation process of TiO2/polymer films as a function UV exposure. LSCM was used to show that both pigment dispersion and durability of the polymer matrix influenced the generation of pits/holes in pigmented polymer film. The type of pigment had a greater influence on the more durable polymer matrix, the acrylic urethane system. The epoxy system showed the greatest extent of degradation regardless of the TiO2 choice. The LCSM results were supported by the ATR-FTIR data.