Search results for: methacrylate copolymer

Authors: Jen-Yuan Wang, Min-Chuan Wang, Der-Jun Jan

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Polymer electrolytes can be classified into four major categories, solid polymer electrolytes (SPEs), gel polymer electrolytes (GPEs), polyelectrolytes and composite polymer electrolytes. SPEs suffer from low ionic conductivity at room temperature. The main problems for GPEs are the poor thermal stability and mechanical properties. In this study, a GPE containing PMMA and succinonitrile is prepared to solve the problems mentioned above, and applied to the assembly of a quasi-solid-state electrochromic device (ECD). In the polymer electrolyte, poly(methyl methacrylate) (PMMA) is the polymer matrix and propylene carbonate (PC) is used as the plasticizer. To enhance the mechanical properties of this GPE, succinonitrile (SN) is introduced as the additive. For the electrochromic materials, tungsten oxide (WO3) is used as the cathodic coloring film, which is fabricated by pulsed dc magnetron reactive sputtering. For the anodic coloring material, Prussian blue nanoparticles (PBNPs) are synthesized and coated on the transparent Sn-doped indium oxide (ITO) glass. The thickness of ITO, WO3 and PB film is 110, 170 and 200 nm, respectively. The size of the ECD is 5×5 cm2. The effect of the introduction of SN into the GPEs is discussed by observing the electrochromic behaviors of the WO3-PB ECD. Besides, the composition ratio of PC to SN is also investigated by measuring the ionic conductivity. The optimized ratio of PC to SN is 4:1, and the ionic conductivity under this condition is 6.34x10-5 S∙cm-1, which is higher than that of PMMA/PC (1.35x10-6 S∙cm-1) and PMMA/EC/PC (4.52x10-6 S∙cm-1). This quasi-solid-state ECD fabricated with the PMMA/SN based GPE shows an optical contrast of ca. 53% at 690 nm. The optical transmittance of the ECD can be reversibly modulated from 72% (bleached) to 19% (darkened), by applying potentials of 1.5 and -2.2 V, respectively. During the durability test, the optical contrast of this ECD remains 44.5% after 2400 cycles, which is 83% of the original one.

Keywords: electrochromism, tungsten oxide, prussian blue, poly(methyl methacrylate), succinonitrile

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Authors: Nikola Toshikj, Michel Ramonda, Sylvain Catrouillet, Jean-Jacques Robin, Sebastien Blanquer

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Biodegradable and biocompatible block copolymers have risen as the golden materials in both medical and environmental applications. Moreover, if their architecture is of controlled manner, higher applications can be foreseen. In the meantime, organocatalytic ROP has been promoted as more rapid and immaculate route, compared to the traditional organometallic catalysis, towards efficient synthesis of block copolymer architectures. Therefore, herein we report novel organocatalytic pathway with guanidine molecules (TBD) for supported synthesis of trimethylene carbonate initiated by poly(caprolactone) as pre-polymer. Pristine PTMC-b-PCL-b-PTMC block copolymer structure, without any residual products and clear desired block proportions, was achieved under 1.5 hours at room temperature and verified by NMR spectroscopies and size-exclusion chromatography. Besides, when elaborating block copolymer films, further stability and amelioration of mechanical properties can be achieved via additional reticulation step of precedently methacrylated block copolymers. Subsequently, stimulated by the insufficient studies on the phase-separation/crystallinity relationship in these semi-crystalline block copolymer systems, their intrinsic thermal and morphology properties were investigated by differential scanning calorimetry and atomic force microscopy. Firstly, by DSC measurements, the block copolymers with χABN values superior to 20 presented two distinct glass transition temperatures, close to the ones of the respecting homopolymers, demonstrating an initial indication of a phase-separated system. In the interim, the existence of the crystalline phase was supported by the presence of melting temperature. As expected, the crystallinity driven phase-separated morphology predominated in the AFM analysis of the block copolymers. Neither crosslinking at melted state, hence creation of a dense polymer network, disturbed the crystallinity phenomena. However, the later revealed as sensible to rapid liquid nitrogen quenching directly from the melted state. Therefore, AFM analysis of liquid nitrogen quenched and crosslinked block copolymer films demonstrated a thermodynamically driven phase-separation clearly predominating over the originally crystalline one. These AFM films remained stable with their morphology unchanged even after 4 months at room temperature. However, as demonstrated by DSC analysis once rising the temperature above the melting temperature of the PCL block, neither the crosslinking nor the liquid nitrogen quenching shattered the semi-crystalline network, while the access to thermodynamical phase-separated structures was possible for temperatures under the poly (caprolactone) melting point. Precisely this coexistence of dual crosslinked/crystalline networks in the same copolymer structure allowed us to establish, for the first time, the shape-memory properties in such materials, as verified by thermomechanical analysis. Moreover, the response temperature to the material original shape depended on the block copolymer emplacement, hence PTMC or PCL as end-block. Therefore, it has been possible to reach a block copolymer with transition temperature around 40°C thus opening potential real-life medical applications. In conclusion, the initial study of phase-separation/crystallinity relationship in PTMC-b-PCL-b-PTMC block copolymers lead to the discovery of novel shape memory materials with superior properties, widely demanded in modern-life applications.

Keywords: biodegradable block copolymers, organocatalytic ROP, self-assembly, shape-memory

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Authors: Parvaneh Eskandari, Rachel O'Reilly

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In the last years, controlling the self-assembly behavior of stimuli-responsive nano-objects, including micelles, vesicles, worm-like, etc., at different conditions is considered a pertinent challenge in the polymer community. The aim of the project was to synthesize aggregation-induced emission (AIE)-active stimuli-responsive polymeric nano-objects to control the self-assemblies morphologies of the prepared nano-objects. Two types of nanoobjects, micelle and vesicles, including PDMAEMA-b-P(BzMA-TPEMA) [PDMAEMA: poly(N,Ndimethylaminoethyl methacrylate); P(BzMA-TPEMA): poly[benzyl methacrylate-co- tetraphenylethene methacrylate]] were synthesized by using reversible addition−fragmentation chain-transfer (RAFT)- mediated polymerization-induced self-assembly (PISA), which combines polymerization and self-assembly in a single step. Transmission electron microscope and dynamic light scattering (DLS) analysis were used to confirm the formed self-assemblies morphologies. The controlled self-assemblies were applied as nitrophenolic compounds (NPCs) adsorbents from wastewater, thanks to their CO2-responsive part, PDMAEMA. Moreover, the fluorescence-active part of the prepared nano-objects, P(BzMA-TPEMA), played a key role in the detection of the NPCs at the aqueous solution. The optical properties of the prepared nano-objects were studied by UV/Vis and fluorescence spectroscopies. For responsivity investigations, the hydrodynamic diameter and Zeta-potential (ζ-potential) of the sample's aqueous solution were measured by DLS. In the end, the prepared nano-objects were used for the detection and adsorption of different NPCs.

Keywords: aggregation-induced emission polymers, stimuli-responsive polymers, reversible addition−fragmentation chain-transfer polymerization, polymerization-induced self-assembly, wastewater treatment

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Authors: Mohamed Saad Gad Elzoghby

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Nanomaterials are widely used nowadays for the consolidation of degraded archaeological limestone. It’s one of the most predominant stones in monumental buildings and statuary works. It is exposed to different weathering processes that cause degradation and the presence of deterioration pattern as cracks, fissures, and granular disintegration. Nanomaterials have been applied to limestone consolidation. Among these nanomaterials are nanolimes, i.e., dispersions of lime nanoparticles in alcohols, and nano-silica, i.e., dispersions of silica nanoparticles in water, promising consolidating products for limestone. It was investigated and applied to overcome the disadvantages of traditional consolidation materials such as lime water, water glass, and paraliod. So, researchers investigated and tested the effectiveness of nanomaterials as consolidation materials for limestone. The present study includes an evaluation of some nanomaterials in consolidation limestone stone in comparison with traditional consolidants. These consolidation materials are nano calcium hydroxide nanolime, and nanosilica. The latter is known commercially as Nano Estel and the former Known as Nanorestore compared to traditional consolidants Wacker OH (ethyl silicate) and Paraloid B72 (a copolymer of ethyl methacrylate and methyl acrylate). The study evaluated the consolidation effectiveness of nanomaterials and traditional consolidants by using followed methods, characterization of physical properties of stone, scanning electron microscopy (SEM), X-ray diffractometry, Fourier transforms infrared spectroscopy, and mechanical properties. The study confirmed that nanomaterials were better in the distribution and encapsulation of calcite grains in limestone, and traditional materials were better in improving the physical properties of limestone. It demonstrated that good results could be achieved through mixtures of nanomaterials and traditional consolidants.

Keywords: nanomaterials, limestone, consolidation, evaluation, weathering, nanolime, nanosilica, scanning electron microscope

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Authors: Mohamed Saad Gad Eloghby

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Nanomaterials are widely used nowadays for the consolidation of degraded archaeological limestone. It’s one of the most predominant stones in monumental buildings and statuary works. Exposure to different weathering processes caused degradation and the presence of deterioration pattern as cracks, fissures, and granular disintegration. Nanomaterials have been applied to limestone consolidation. Among these nanomaterials are nanolimes, i.e., dispersions of lime nanoparticles in alcohols and nanosilica, i.e., dispersions of silica nanoparticles in water promising consolidating products for limestone. It was investigated and applied to overcome the disadvantages of traditional consolidation materials such as lime water, water glass and paraliod. So, researchers investigated and tested the effectiveness of nanomaterials as consolidation materials for limestone. The present study includes the evaluation of some nano materials in consolidation limestone stone in comparison with traditional consolidantes. These consolidation materials are nano calcium hydroxide nanolime and nanosilica. The latter is known commercially as Nano Estel and the former is known as Nanorestore compared to traditional consolidantes Wacker OH (ethyl silicate) and Paraloid B72 (a copolymer of ethyl methacrylate and methyl acrylate). The study evaluated the consolidation effectiveness of nanomaterials and traditional consolidantes by using followed methods, Characterization of physical properties of stone, Scanning electron microscopy (SEM), X-ray diffractometry, Fourier transform infrared spectroscopy and Mechanical properties. The study confirmed that nanomaterials were better in the distribution and encapsulation of calcite grains in limestone, and traditional materials were better in improving the physical properties of limestone. It demonstrated that good results can be achieved through mixtures of nanomaterials and traditional consolidants.

Keywords: nanomaterials, limestone, consolidation, evaluation, weathering, nanolime, nanosilica, scanning electron microscope

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Authors: Pemika Ketsuwan, Pitt Supaphol, Manit Nithitanakul

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A typical used of ethylene methyl acrylate (EMA) gasket is in the manufacture of optical lens, and often, they are deteriorated rapidly due to high temperature during the process. The objective of this project is to improve the thermal stability of the EMA copolymer gasket by preparing EMA with cellulose and silica composites. Hydroxy propyl methyl cellulose (HPMC) and Carboxy methyl cellulose (CMC) were used in preparing of EMA/cellulose composites and fumed silica (SiO2) was used in preparing EMA/silica composites with different amounts of filler (3, 5, 7, 10, 15 wt.%), using a twin screw extruder at 160 °C and the test specimens were prepared by the injection molding machine. The morphology and dispersion of fillers in the EMA matrix were investigated by field emission scanning electron microscopy (FESEM). The thermal stability of the composite was determined by thermal gravimetric analysis (TGA), and differential scanning calorimeter (DSC). Mechanical properties were evaluated by tensile testing. The developed composites were found to enhance thermal and mechanical properties when compared to that of the EMA copolymer alone.

Keywords: ethylene methyl acrylate, HPMC, Silica, Thermal stability

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Authors: Rajani Kant Rai, Jayakrishnan Athipet

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There have been several attempts to prepare polymers with antimicrobial properties by doping with various N-halamines. Hydantoins (Cyclic N-halamine) is of importance due to their stability rechargeable chloroamide function, broad-spectrum anti-microbial action and ability to prevent resistance to the organisms. Polymerizable hydantoins are synthesized by tethering vinyl moieties to 5,5,-dialkyl hydantoin sacrificing the imide hydrogen in the molecule thereby restricting the halogen capture only to the amide nitrogen that results in compromised antibacterial activity. In order to increase the activity of the antimicrobial polymer, we have developed a scheme to maximize the attachment of chlorine to the amide and the imide moieties of hydantoin. Vinyl hydantoin monomer, (Z)-5-(4-((3-methylbuta-1,3-dien-2-yl)oxy)benzylidene)imidazolidine-2,4-dione (MBBID) was synthesized and copolymerized with a commercially available monomer, methyl methacrylate, by free radical polymerization. The antimicrobial activity of hydantoin is strongly dependent on their surface area and hence their microbial activity increases when incorporated in microspheres or nanoparticles as compared to their bulk counterpart. In this regard, smooth and rough surface microsphere of the vinyl monomer (MBBID) with commercial monomer was synthesized. The oxidative chlorine content of the copolymer ranged from 1.5 to 2.45 %. Further, to demonstrate the water purification potential, the thin column was packed with smooth or rough microspheres and challenged with simulated contaminated water that exhibited 6 log kill (total kill) of the bacteria in 20 minutes of exposure with smooth (25 mg/ml) and rough microsphere (15.0 mg/ml).

Keywords: cyclic N-halamine, vinyl hydantoin monomer, rough surface microsphere, simulated contaminated water

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Authors: Robert Kimutai Tewo, Hilary Limo Rutto, Tumisang Seodigeng

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The rheological and morphological properties of paraffin wax, linear low-density polyethylene (LLDPE), and poly (methyl methacrylate) (PMMA) microbeads formulations were prepared via an extrusion process. The blends were characterized by rheometry, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the viscosity of the blends increased as compared to that of neat wax. SEM confirmed that LLDPE alters the wax crystal habit at higher concentrations. The rheological experimental data fitted with predicted data using the modified Krieger and Dougherty expression. The SEM micrograph of wax/LLDPE/PMMA revealed a near-perfect spherical nature for the filler particles in the wax/EVA polymer matrix. The FT-IR spectra show the deformation vibrations stretch of a long-chain aliphatic hydrocarbon (C-H) and also the presence of carbonyls absorption group denoted by -C=O- stretch.

Keywords: investment casting pattern, paraffin wax, LLDPE, PMMA, rheological properties, modified Krieger and Dougherty expression

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Authors: Ramita Vongrat, Pornsri Sapsrithong, Manit Nithitanakul

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In this work, blends of polyamide 6 (PA6) and polybutylene terephthalate (PBT) were successfully prepared. The effect of epoxidized natural rubber (ENR-25) and n butyl acrylate glycidyl methacrylate ethylene (EBa-GMA) as a compatibilizer on properties of PA6/PBT blends was also investigated by varying amount of ENR-50 and EBa-GMA, i.e., 0, 0.1, 0.5, 5 and 10 phr. All blends were prepared and shaped by using twin-screw extruder at 230 °C and injection molding machine, respectively. All test specimens were characterized by phase morphology, impact strength, tensile, flexural properties, and hardness. The results exhibited that phase morphology of PA6/PBT blend without compatibilizer was incompatible. This could be attributed to poor interfacial adhesion between the two polymers. SEM micrographs showed that the addition of ENR-25 and EBa-GMA improved the compatibility of PA6/PBT blends. With the addition of ENR-50 as a compatibilizer, the uniformity and the maximum reduction of dispersed phase size were observed. Additionally, the results indicate that, as the amount of ENR-25 increased, and EBa-GMA increased, the mechanical properties, including stress at the peak, tensile modulus, and izod impact strength, were also improved.

Keywords: EBa-GMA, epoxidized natural rubber-25, polyamide 6, polybutylene terephthalate

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Authors: Jorge Prada, Christina Cordes, Carsten Harms, Walter Lang

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The development of microfluidic-based biosensors over the last years has shown an increasing employ of thermoplastic polymers as constitutive material. Their low-cost production, high replication fidelity, biocompatibility and optical-mechanical properties are sought after for the implementation of disposable albeit functional lab-on-chip solutions. Among the range of thermoplastic materials on use, the Cyclo-Olefin Copolymer (COC) stands out due to its optical transparency, which makes it a frequent choice as manufacturing material for fluorescence-based biosensors. Moreover, several processing techniques to complete a closed COC microfluidic biosensor have been discussed in the literature. The reported techniques differ however in their implementation, and therefore potentially add more or less complexity when using it in a mass production process. This work introduces and reports results on the application of a purely thermal bonding process between COC substrates, which were produced by the hot-embossing process, and COC foils containing screen-printed circuits. The proposed procedure takes advantage of the transition temperature difference between two COC grades foils to accomplish the sealing of the microfluidic channels. Patterned heat injection to the COC foil through the COC substrate is applied, resulting in consistent channel geometry uniformity. Measurements on bond strength and bursting pressure are shown, suggesting that this purely thermal bonding process potentially renders a technique which can be easily adapted into the thermoplastic microfluidic chip production workflow, while enables a low-cost as well as high-quality COC biosensor manufacturing process.

Keywords: biosensor, cyclo-olefin copolymer, hot embossing, thermal bonding, thermoplastics

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Authors: Naima Boudieb, Mohamed Loucif Seaid, Imad Rati, Imane Benammane

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The aim of this study is to synthesis of a copolymer PANI/PEDOT:PSS by electrochemical means to apply in supercapacitors. Polyaniline (PANI) is a conductive polymer; it was synthesized by electrochemical polymerization. It exhibits very stable properties in different environments, whereas PEDOT:PSS is a conductive polymer based on poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(styrene sulfonate)(PSS). It is commonly used with polyaniline to improve its electrical conductivity. Several physicochemical and electrochemical techniques were used for the characterization of PANI/PEDOT:PSS: cyclic voltammetry (VC), electrochemical impedance spectroscopy (EIS), open circuit potential, SEM, X-ray diffraction, etc. The results showed that the PANI/PEDOT:PSS composite is a promising material for supercapacitors due to its high electrical conductivity and high porosity. Electrochemical and physicochemical characterization tests have shown that the composite has high electrical and structural performances, making it a material of choice for high-performance energy storage applications.

Keywords: energy storage, supercapacitors, SIE, VC, PANI, poly(3, 4-ethylenedioxythiophene, PEDOT, polystyrene sulfonate

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Authors: Paula C Arroyo, Norma A Sánchez, Mikhail Tlenkopatchev

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The continuous growth in population has resulted in an increment in road construction. The road construction requires more lasting and resistant pavements. Among the different applications of polymers, the reinforcement of pavements throw the modification of asphalt has demonstrated to be an area of special interest for new polymers. The modified asphalt should exhibit a considerable good performance, good elastic properties and an increment in the performance grade (PG). Some of the current polymers used in asphalt are styrene butadiene styrene (SBS), poly(n-butyl methacrylate)-(glycidyl methacrylate) and ethylene-vinyl acetate EVA. The goal of this study was to synthesize low molecular weight (2,000 – 150,000 D) telechelic polymers to be applied at low concentrations in asphalt in order to modify its rheological properties and make it more resistant and durable. The telechelic polymers were obtained from different molar relationships between tensioned and functionalized olefins by ring opening metathesis polymerization (ROMP) and cross metathesis (CR). The synthesis was carried out under inert conditions with Grubbs second generation catalyst. The reaction efficiency was superior to 96% and telechelic polymers were characterized. The telechelic polymers were used to modify asphalt and the rheological properties of the modified asphalt were evaluated finding that at low concentrations (1%) the PG increased in one or two degrees.

Keywords: asphalt polymers, metathesis polymers, telechelic polymers, modified asphalt

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Authors: A. Aslihan Gokaltun, Martin L. Yarmush, Ayse Asatekin, O. Berk Usta

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In the last decade microfabrication processes including rapid prototyping techniques have advanced rapidly and achieved a fairly matured stage. These advances encouraged and enabled the use of microfluidic devices by a wider range of users with applications in biological separations, and cell and organoid cultures. Accordingly, a significant current challenge in the field is controlling biomolecular interactions at interfaces and the development of novel biomaterials to satisfy the unique needs of the biomedical applications. Poly(dimethylsiloxane) (PDMS) is by far the most preferred material in the fabrication of microfluidic devices. This can be attributed its favorable properties, including: (1) simple fabrication by replica molding, (2) good mechanical properties, (3) excellent optical transparency from 240 to 1100 nm, (4) biocompatibility and non-toxicity, and (5) high gas permeability. However, high hydrophobicity (water contact angle ~108°±7°) of PDMS often limits its applications where solutions containing biological samples are concerned. In our study, we created a simple, easy method for modifying the surface chemistry of PDMS microfluidic devices through the addition of surface-segregating additives during manufacture. In this method, a surface segregating copolymer is added to precursors for silicone and the desired device is manufactured following the usual methods. When the device surface is in contact with an aqueous solution, the copolymer self-organizes to expose its hydrophilic segments to the surface, making the surface of the silicone device more hydrophilic. This can lead to several improved performance criteria including lower fouling, lower non-specific adsorption, and better wettability. Specifically, this approach is expected to be useful for the manufacture of microfluidic devices. It is also likely to be useful for manufacturing silicone tubing and other materials, biomaterial applications, and surface coatings.

Keywords: microfluidics, non-specific protein adsorption, PDMS, PEG, copolymer

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Authors: Van Tran Thi Thuy, Cheol Won Lim, Dukjoon Kim

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A series of biodegradable copolymers based on polyaspartamide (PASPAM) were synthesized by grafting hydrophilic O-(2-aminoethyl)-O'-methylpoly(ethylene glycol) (MPEG), hydrophobic cholic acid (CA), and pH-sensitive hydrazine (Hyd) segments on a PASPAM backbone. The hydrazine group was effectively cleaved to release doxorubicin (DOX) conjugated on PASPAM in an acidic environment. The chemical structure of the polymer and the degree of substitution of each graft segment were analyzed using FT-IR and 1H-NMR spectroscopy. The size of the MPEG/Hyd/CA-g-PASPAM copolymer self-aggregates was examined by dynamic light scattering (DLS) and transmission electron microscope (TEM). The mean diameter of the self - aggregates increased from 125 to 200 nm at pH 7.4, as the degree of substitution of CA increased from 10 to 20 %. The release kinetics of DOX was strongly affected by the pH of the releasing medium. While less than 30% of the DOX-loaded was released in about 30 h at pH 7.4, more than 60% was released at pH 5.0 within the same time. The viability tests of human breast cancer cells (MCF-7) and human embryonic kidney cells (293T) show the potential application of MPEG/Hyd/CA-g-PASPAM copolymer self-aggregates in the controlled intracellular delivery for cancer treatments.

Keywords: pH-sensitive, drug delivery, polyaspartamide, self-assembly, nano-aggregates

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Authors: M. S. Mrudula, M. R. Gopinathan Nair

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In order to utilize the natural rubber for developing new green polymeric materials for specialty applications, we have prepared natural rubber and polyethylene oxide based polymeric networks by two shot method. The polymeric networks thus formed have been used as chelating exchanger for metal ion binding. Chelating exchangers are, in general, coordinating copolymers containing one or more electron donor atoms such as N, S, O, and P that can form coordinate bonds with metals. Hydrogels are water- swollen network of hydrophilic homopolymer or copolymers. They acquire a great interest due to the facility of the incorporation of different chelating groups into the polymeric networks. Such polymeric hydrogels are promising materials in the field of hydrometallurgical applications and water purification due to their chemical stability. The current study discusses the swelling response of the polymeric networks as a function of time, temperature, pH and [NaCl] and sorption studies. Equilibrium swelling has been observed to depend on both structural aspects of the polymers and environmental factors. Metal ion sorption shows that these polymeric networks can be used for removal, separation, and enrichment of metal ions from aqueous solutions and can play an important role for environmental remediation of municipal and industrial wastewater.

Keywords: block copolymer, adsorption, chelating exchanger, swelling study, polymer, metal complexes

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Authors: A. Sezai Sarac

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Acrylonitrile (AN) copolymers with typical comonomers of vinyl acetate (VAc) or methyl acrylate (MA) exhibit better mechanical behaviors than its homopolymer. To increase processability of conjugated polymer, and to obtain a hybrid nano-structure multi-stepped emulsion polymerization was applied. Such products could be used in, i.e., drug-delivery systems, biosensors, gas-sensors, electronic compounds, etc. Incorporation of a number of flexible comonomers weakens the dipolar interactions among CN and thereby decreases melting point or increases decomposition temperatures of the PAN based copolymers. Hence, it is important to consider the effect of comonomer on the properties of PAN-based copolymers. Acrylonitrile vinylacetate (AN–VAc ) copolymers have the significant effect to their thermal behavior and are also of interest as precursors in the production of high strength carbon fibers. AN is copolymerized with one or two comonomers, particularly with vinyl acetate The copolymer of AN and VAc can be used either as a plastic (VAc > 15 wt %) or as microfibers (VAc < 15 wt %). AN provides the copolymer with good processability, electrochemical and thermal stability; VAc provides the mechanical stability. The free radical copolymerization of AN and VAc copolymer and core Shell structure of polyprrole composites,and nanofibers of poly(m-anthranilic acid)/polyacrylonitrile blends were recently studied. Free radical copolymerization of acrylonitrile (AN) – with different comonomers, i.e. acrylates, and styrene was realized using ammonium persulfate (APS) in the presence of a surfactant and in-situ polymerization of conjugated polymers was performed in this reaction medium to obtain core-shell nano particles. Nanofibers of such nanoparticles were obtained by electrospinning. Morphological properties of nanofibers are investigated by scanning electron microscopy (SEM) and atomic force spectroscopy (AFM). Nanofibers are characterized using Fourier Transform Infrared - Attenuated Total Reflectance spectrometer (FTIR-ATR), Nuclear Magnetic Resonance Spectroscopy (1H-NMR), differential scanning calorimeter (DSC), thermal gravimetric analysis (TGA), and Electrochemical Impedance Spectroscopy. The electrochemical Impedance results of the nanofibers were fitted to an equivalent curcuit by modelling (ECM).

Keywords: core shell nanoparticles, nanofibers, ascrylonitile copolymers, hybrid nanostructures

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Authors: Ashish Kumar, T. Venkatappa Rao, Subhendu Ray Chowdhury, S. V. S. Ramana Reddy

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The main objective of this work is to determine the influence of electron beam irradiation on thermal and mechanical properties of Poly (lactic acid) (PLA)/Poly (ethylene-co-glycidyle methacrylate) (PEGM)/Hexagonal boron nitride (HBN) blend-composites. To reduce the brittleness and improve the toughness of PLA, the PLA/PEGM blend is prepared by using twin-screw Micro compounder. However, the heat deflection temperature (HDT) and other tensile properties were reduced. The HBN has been incorporated into the PLA/PEGM blend as part per hundred i.e. 5 phr and 10phr to improve the HDT. The prepared specimens of blend and blend-composites were irradiated to high energy (4.5 MeV) electron beam (E-beam) at different radiation doses to introduce the cross linking among the polymer chains and uniform dispersion of HBN particles in the PLA/PEGM/HBN blend-composites. The further improvement in the notched impact strength and HDT have been achieved in the case of PLA/PEGM/HBN blend-composites. The irradiated PLA/PEGM/HBN 5phr blend composite shows high notched impact strength and HDT as compared to other unirradiated and E-beam irradiated blend and blend-composites. The improvements in the yield strength and tensile modulus have also been noticed in the case of E-beam irradiated PLA/PEGM/HBN blend-composites as compared to unirradiated blend-composites.

Keywords: blend-composite, e-beam, HDT, PEGM, PLA

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Authors: Hiroyuki Aoki

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Polymeric materials are often used in a form of thin film such as food wrap and surface coating. In such the applications, polymer films thinner than 100 nm have been often used. The thickness of such the ultra-thin film is less than the unperturbed size of a polymer chain; therefore, the polymer chain in an ultra-thin film is strongly constrained. However, the details on the constrained dynamics of polymer molecules in ultra-thin films are still unclear. In the current study, the segmental dynamics of single polymer chain was directly investigated by fluorescence microscopy. The individual chains of poly(alkyl methacrylate) labeled by a perylenediimide dye molecule were observed by a highly sensitive fluorescence microscope in a defocus condition. The translational and rotational diffusion of the center segment in a single polymer chain was directly analyzed. The segmental motion in a thin film with a thickness of 10 nm was found to be suppressed compared to that in a bulk state. The detailed analysis of the molecular motion revealed that the diffusion rate of the in-plane rotation was similar to the thin film and the bulk; on the other hand, the out-of-plane motion was restricted in a thin film. This result indicates that the spatial restriction in an ultra-thin film thinner than the unperturbed chain dimension alters the dynamics of individual molecules in a polymer system.

Keywords: polymer materials, single molecule, molecular motion, fluorescence microscopy, super-resolution techniques

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Authors: Vishal Kumar Gupta

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Purpose: This study has been undertaken to develop novel pH sensitive interpenetrating network hydrogel beads. Methods: The pH sensitive PAAM-g-Guar gum copolymer was synthesized by free radical polymerization followed by alkaline hydrolysis. Beads of guar gum-grafted-polyacrylamide and sodium Carboxy methyl cellulose (Na CMC) loaded with Pantoprazole sodium were prepared and evaluated for pH sensitivity, swelling properties, drug entrapment efficiency and in vitro drug release characteristics. Seven formulations were prepared for the drug with varying polymer and cross linker concentrations. Results: The grafting and alkaline hydrolysis reactions were confirmed by FT-IR spectroscopy. Differential scanning calorimetry was carried out to know the compatibility of encapsulated drug with the polymers. Scanning electron microscopic study revealed that the IPN beads were spherical. The entrapment efficiency was found to be in the range of 85-92%. Particle size analysis was carried out by optical microscopy. As the pH of the medium was changed from 1.2 to 7.4, a considerable increase in swelling was observed for all beads. Increase in the copolymer concentration showed sustained the drug release up to 12 hrs. Drug release from the beads followed super case II transport mechanism. Conclusion: It was concluded that guar gum-acrylamide beads, cross-linked with aluminum chloride offer an opportunity for controlled drug release of pantoprazole sodium.

Keywords: IPN, hydrogels, DSC, SEM

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Authors: Asli Beyler Çi̇ği̇l, Memet Vezi̇r Kahraman

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Organic–inorganic hybrids have become an effective source of advanced materials because they combine the advantages of both the organic moiety such as flexibility, low dielectric constant, and processability, and inorganic moiety as rigidity, strength, durability, and thermal stability. By incorporating cross-linkable side chains, the hybrid materials can be made photosensitive and UV curable, which offers many advantages including low processing temperature, low equipment cost and compatibility. In this study, uv-curable organic-inorganic hybrid material, which was contained surface modified polyaniline particles (PANI), was prepared. PANI surface photografted with hydroxy ethyl methacrylate (HEMA) to produce hydroxyl groups. Hydroxyl functionalized PANI/HEMA was acrylated using isocyanato ethyl methacrylate (IEM) in order to improve the dispersion and interfacial interaction in composites. UV-curable formulation was prepared by mixing the surface modified PANI, polyethylene glycol diacrylate (PEGDA), trimethylolpropane triacrylate (TMPTA), hydrolized 3- methacryloxypropyltrimethoxysilane (hyd. MEMO) and photoinitiator. Chemical structure of nano-hybrid material was characterized by FTIR. FTIR spectra showed that the photografting of PANI was prepared successfully. Thermal properties of the nano-hybrid material were determined by thermogravimetric analysis (TGA). The morphology of the nano-hybrid material was performed by scanning electron microscopy (SEM).

Keywords: polyaniline, photograft, sol-gel, uv-curable polymer

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Authors: Florin Leon, Silvia Curteanu

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Developing complete mechanistic models for polymerization reactors is not easy, because complex reactions occur simultaneously; there is a large number of kinetic parameters involved and sometimes the chemical and physical phenomena for mixtures involving polymers are poorly understood. To overcome these difficulties, empirical models based on sampled data can be used instead, namely regression methods typical of machine learning field. They have the ability to learn the trends of a process without any knowledge about its particular physical and chemical laws. Therefore, they are useful for modeling complex processes, such as the free radical polymerization of methyl methacrylate achieved in a batch bulk process. The goal is to generate accurate predictions of monomer conversion, numerical average molecular weight and gravimetrical average molecular weight. This process is associated with non-linear gel and glass effects. For this purpose, an adaptive sampling technique is presented, which can select more samples around the regions where the values have a higher variation. Several machine learning methods are used for the modeling and their performance is compared: support vector machines, k-nearest neighbor, k-nearest neighbor and random forest, as well as an original algorithm, large margin nearest neighbor regression. The suggested method provides very good results compared to the other well-known regression algorithms.

Keywords: batch bulk methyl methacrylate polymerization, adaptive sampling, machine learning, large margin nearest neighbor regression

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Authors: S. M. Anisuzzaman, Sariah Abang, Awang Bono, D. Krishnaiah, N. M. Ismail, G. B. Sandrison

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Wax and asphaltene are high molecular weighted compounds that contribute to the stability of crude oil at a dispersed state. Transportation of crude oil along pipelines from the oil rig to the refineries causes fluctuation of temperature which will lead to the coagulation of wax and flocculation of asphaltenes. This paper focuses on the prevention of wax and asphaltene precipitate deposition on the inner surface of the pipelines by using a wax inhibitor and an asphaltene dispersant. The novelty of this prevention method is the combination of three substances; a wax inhibitor dissolved in a wax inhibitor solvent and an asphaltene solvent, namely, ethylene-vinyl acetate (EVA) copolymer dissolved in methylcyclohexane (MCH) and toluene (TOL) to inhibit the precipitation and deposition of wax and asphaltene. The objective of this paper was to optimize the percentage composition of each component in this inhibitor which can maximize the viscosity reduction of crude oil. The optimization was divided into two stages which are the laboratory experimental stage in which the viscosity of crude oil samples containing inhibitor of different component compositions is tested at decreasing temperatures and the data optimization stage using response surface methodology (RSM) to design an optimizing model. The results of experiment proved that the combination of 50% EVA + 25% MCH + 25% TOL gave a maximum viscosity reduction of 67% while the RSM model proved that the combination of 57% EVA + 20.5% MCH + 22.5% TOL gave a maximum viscosity reduction of up to 61%.

Keywords: asphaltene, ethylene-vinyl acetate, methylcyclohexane, toluene, wax

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Authors: Muhammad Naeem, Juho Lee, Jin-Wook Yoo

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In this study, we hypothesized that prolonged gastrointestinal transit at the inflamed colon conferred by a pH-triggered mucoadhesive smart nanoparticulate drug delivery system aids in achieving selective and sustained levels of the drug within the inflamed colon for the treatment of ulcerative colitis. We developed budesonide-loaded pH-sensitive charge-reversal solid lipid nanoparticles (SLNs) using a hot homogenization method. Polyetylenimine (PEI) was used to render SLNs cationic (PEI-SLNs). Eudragit S100 (ES) was coated on PEI-SLNs for pH-trigger charge-reversal SLNs (ES-PEI-SLNs). Therapeutic potential of the prepared SNLs formulation was evaluated in ulcerative colitis in mice. The transmission electron microscopy, zeta size and zeta potential data showed the successful formation of SLNs formulations. SLNs and PEI-SLNs showed burst drug release in acidic pH condition mimicking stomach and early small intestine environment which limiting their application as oral delivery systems. However, ES-PEI-SLNs prevented a burst drug release in acidic pH conditions and showed sustained release at a colonic pH. Most importantly, the surface charge of ES-PEI-SLNs switched from negative to positive in colonic conditions by pH-triggered removal of ES coating and accumulated selectively in inflamed colon. Furthermore, a charge reversal ES-PEI-SLNs showed a superior mitigation of dextran sulfate sodium (DSS)-induced acute colitis in mice as compared to SLNs and PEI-SLNs treated groups. Moreover, histopathological analysis of distal colon sections stained with hematoxylin/eosin and E-cadherin immunostaining revealed attenuated inflammation in an ES-PEI-SLNs-treated group. We also found that ES-PEI-SLNs markedly reduced the myeloperoxidase level and expression of TNF-alpha in colon tissue. Our results suggest that the pH-triggered charge reversal SLNs presented in this study would be a promising approach for ulcerative colitis therapy.

Keywords: solid lipid nanoparticles, stimuli-triggered charge-reversal, ulcerative colitis, methacrylate copolymer, budesonide

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Authors: Sameh A. S. Thabit Alariqi

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Our previous studies aimed to investigate the biodegradation of γ-sterilized polyolefins in composting and microbial culture environments at different doses and γ-dose rates. It was concluded from the previous studies that the pretreatment of γ-irradiation can accelerate the biodegradation of neat polymer matrix in biotic conditions significantly. A similar work was carried out to study the stabilization of γ-sterilized polyolefins using different mixtures of stabilizers which are approved for food-contact applications. Ethylene-propylene (EP) copolymer has been melt-mixed with hindered amine stabilizers (HAS), phenolic antioxidants and hydroperoxide decomposers. Results were discussed by comparing the stabilizing efficiency, combination and consumption of stabilizers and the synergistic and antagonistic effects was explained through the interaction between the stabilizers. In this attempt, we have aimed to study the influence of the synergistic and antagonistic mixtures of oligomeric stabilizers on the biodegradation of the γ-irradiated polyolefins in composting and microbial culture. Neat and stabilized films of EP copolymer irradiated under γ-radiation and incubated in compost and fungal culture environments. The changes in functional groups, surface morphology, mechanical properties and intrinsic viscosity in polymer chains were characterized by FT-IR spectroscopy, SEM, instron, and viscometric measurements respectively. Results were discussed by comparing the effect of different stabilizers, stabilizers mixtures on the biodegradation of the γ-irradiated polyolefins. It was found that the biodegradation significantly depends on the components of stabilization system, mobility, interaction, and consumption of stabilizers.

Keywords: biodegradation, γ-irradiation, polyolefins, stabilization

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Authors: Udayakumar Vee, Franck Quero

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Zwitterionic polymers generally have been viewed as a new class of antimicrobial and non-fouling materials. They offer a broad versatility for chemical modification and hence great freedom for accurate molecular design, which bear an equimolar number of homogenously distributed anionic and cationic groups along their polymer chains. This study explores the effectiveness of the auxetic zwitterion carboxylate/sulfonate hydrogel in the diabetic-induced mouse model. A series of silver metal-doped auxetic zwitterion carboxylate/sulfonate/vinylaniline copolymer hydrogels is designed via a 3D printer. Zwitterion monomers have been characterized by FT-IR and NMR techniques. The effect of changing the monomers and different loading ratios of Ag over zwitterion on the final hydrogel materials' antimicrobial properties and biocompatibility will be investigated in detail. The synthesized auxetic hydrogel has been characterized using a wide range of techniques to help establish the relationship between molecular level and macroscopic properties of these materials, including mechanical and antibacterial and biocompatibility and wound healing ability. This work's comparative studies and results provide new insights and guide us in choosing a better auxetic structured material for a broad spectrum of wound healing applications in the animal model. We expect this approach to provide a versatile and robust platform for biomaterial design that could lead to promising treatments for wound healing applications.

Keywords: auxetic, zwitterion, carboxylate, sulfonate, polymer, wound healing

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Authors: Udayakumar Veerabagu, Franck Quero

Abstract:

Zwitterion carboxylate and sulfonate polymers generally have been viewed as a new class of antimicrobial and non-fouling materials. They offer a broad versatility for chemical modification and hence great freedom for accurate molecular design, which bear an equimolar number of homogenously distributed anionic and cationic groups along their polymer chains. This study explores the effectiveness of the auxetic zwitterion carboxylate/sulfonate hydrogel in the diabetic-induced mouse model. A series of silver metal-doped auxetic zwitterion carboxylate/sulfonate/vinylaniline copolymer hydrogels is designed via a 3D printer. Zwitterion monomers have been characterized by FT-IR and NMR techniques. The effect of changing the monomers and different loading ratios of Ag over zwitterion on the final hydrogel materials' antimicrobial properties and biocompatibility will be investigated in detail. The synthesized auxetic hydrogel has been characterized using a wide range of techniques to help establish the relationship between molecular level and macroscopic properties of these materials, including mechanical and antibacterial and biocompatibility and wound healing ability. This work's comparative studies and results provide new insights and guide us in choosing a better auxetic structured material for a broad spectrum of wound healing applications in the animal model. We expect this approach to provide a versatile and robust platform for biomaterial design that could lead to promising treatments for wound healing applications.

Keywords: auxetic, zwitterion, carboxylate, sulfonate, polymer, wound healing

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Authors: Bo Keun Lee, Doo Yeon Kwon, Ji Hoon Park, Gun Hee Lee, Ji Hye Baek, Heung Jae Chun, Young Joo Koh, Moon Suk Kim

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Thermo-responsive materials are viscoelastic materials that undergo a sol-to-gel phase transition at a specific temperature and many materials have been developed. MPEG-b-PCL (MPC) as a thermo-responsive material contained hydrophilic and hydrophobic segments and it formed an ordered crystalline structure of hydrophobic PCL segments in aqueous solutions. The ordered crystalline structure packed tightly or aggregated and finally induced an aggregated gel through intra- and inter-molecular interactions as a function of temperature. Thus, we introduced anionic and cationic groups into the end positions of the PCL chain to alter the hydrophobicity of the PCL segment. Introducing anionic and cationic groups into the PCL end position altered their solubility by changing the crystallinity and hydrophobicity of the PCL block domains. These results indicated that the properties of the end group in the hydrophobic PCL blockand the balance between hydrophobicity and hydrophilicity affect thermo-responsivebehavior of the copolymers in aqueous solutions. Thus, we concluded that determinant of the temperature-dependent thermo-responsive behavior of MPC depend on the ionic end group in the PCL block. So, we introduced zwitterionic end groups to investigate the thermo-responsive behavior of MPC. Methoxypoly(ethylene oxide) and ε-caprolactone (CL) were randomly copolymerized that introduced varying hydrophobic PCL lengths and an MPC featuring a zwitterionic sulfobetaine (MPC-ZW) at the chain end of the PCL segment. The MPC and MPC-ZW copolymers were obtained formed sol-state at room temperature when prepared as 20-wt% aqueous solutions. The solubility of MPC decreased when the PCL block was increased from molecular weight. The solubilization time of MPC-2.4k was around 20 min and MPC-2.8k, MPC-3.0k increased to 30 min and 1 h, respectively. MPC-3.6k was not solubilized. In case of MPC-ZW 3.6k, However, the zwitterion-modified MPC copolymers were solubilized in 3–5 min. This result indicates that the zwitterionic end group of the MPC-ZW diblock copolymer increased the aqueous solubility of the diblock copolymer even when the length of the hydrophobic PCL segment was increased. MPC and MPC-ZW diblock copolymers that featuring zwitterionic end groups were synthesized successfully. The sol-to-gel phase-transition was formed that specific temperature depend on the length of the PCL hydrophobic segments introduced and on the zwitterion groups attached to the MPC chain end. This result indicated that the zwitterionic end groups reduced the hydrophobicity in the PCL block and changed the solubilization. The MPC-ZW diblock copolymer can be utilized as a potential injectable drug and cell carrier.

Keywords: thermo-responsive material, zwitterionic, hydrophobic, crystallization, phase transition

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Authors: Eda Cagli, Irem Erel Goktepe

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Externally triggered and effective release of therapeutics from polymer nanoplatforms is one of the key issues in cancer treatment. In this study, we aim to prepare polymer multilayer films which are stable at physiological conditions (little or no drug release) but release drug molecules at acidic pH and via application of AC magnetic field. First, novel stimuli responsive diblock copolymers composed of pH- and temperature-responsive blocks were synthesized. Then, block copolymer micelles with pH-responsive core and temperature responsive coronae will be obtained via pH-induced self-assembly of these block copolymers in aqueous environment. A model anticancer drug, e.g. Doxorubicin will be loaded in the micellar cores. Second, superparamagnetic nanoparticles will be synthesized. Magnetic nanoparticles and drug loaded block copolymer micelles will be used as building blocks to construct the multilayers. To mimic the acidic nature of the tumor tissues, Doxorubicin release from the micellar cores will be induced at acidic conditions. Moreover, Doxorubicin release from the multilayers will be facilitated via magnetothermal trigger. Application of AC magnetic field will induce the heating of magnetic nanoparticles resulting in an increase in the temperature of the polymer platform. This increase in temperature is expected to trigger conformational changes on the temperature-responsive micelle coronae and facilitate the release of Doxorubicin from the surface. Such polymer platform may find use in biomedical applications.

Keywords: layer-by-layer films, magnetothermal trigger, smart polymers, stimuli responsive

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Authors: Yihenew Simegniew Birhan, Hsieh Chih Tsai

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The recent advancements in synthetic chemistry and nanotechnology fostered the development of different nanocarriers for enhanced intracellular delivery of pharmaceutical agents to tumor cells. Polymeric micelles (PMs), characterized by small size, appreciable drug loading capacity (DLC), better accumulation in tumor tissue via enhanced permeability and retention (EPR) effect, and the ability to avoid detection and subsequent clearance by the mononuclear phagocyte (MNP) system, are convenient to improve the poor solubility, slow absorption and non-selective biodistribution of payloads embedded in their hydrophobic cores and hence, enhance the therapeutic efficacy of chemotherapeutic agents. Recently, redox-responsive polymeric micelles have gained significant attention for the delivery and controlled release of anticancer drugs in tumor cells. In this study, we synthesized redox-responsive diselenide bond containing amphiphilic polymer, Bi(mPEG-PLGA)-Se₂ from mPEG-PLGA, and 3,3'-diselanediyldipropanoic acid (DSeDPA) using DCC/DMAP as coupling agents. The successful synthesis of the copolymers was verified by different spectroscopic techniques. Above the critical micelle concentration, the amphiphilic copolymer, Bi(mPEG-PLGA)-Se₂, self-assembled into stable micelles. The DLS data indicated that the hydrodynamic diameter of the micelles (123.9 ± 0.85 nm) was suitable for extravasation into the tumor cells through the EPR effect. The drug loading content (DLC) and encapsulation efficiency (EE) of DOX-loaded micelles were found to be 6.61 wt% and 54.9%, respectively. The DOX-loaded micelles showed initial burst release accompanied by sustained release trend where 73.94% and 69.54% of encapsulated DOX was released upon treatment with 6mM GSH and 0.1% H₂O₂, respectively. The biocompatible nature of Bi(mPEG-PLGA)-Se₂ copolymer was confirmed by the cell viability study. In addition, the DOX-loaded micelles exhibited significant inhibition against HeLa cells (44.46%), at a maximum dose of 7.5 µg/mL. The fluorescent microscope images of HeLa cells treated with 3 µg/mL (equivalent DOX concentration) revealed efficient internalization and accumulation of DOX-loaded Bi(mPEG-PLGA)-Se₂ micelles in the cytosol of cancer cells. In conclusion, the intelligent, biocompatible, and the redox stimuli-responsive behavior of Bi(mPEG-PLGA)-Se₂ copolymer marked the potential applications of diselenide-linked mPEG-PLGA micelles for the delivery and on-demand release of chemotherapeutic agents in cancer cells.

Keywords: anticancer drug delivery, diselenide bond, polymeric micelles, redox-responsive

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Authors: Pixiang Wang, Shaoyang Liu, Yucheng Peng

Abstract:

Polypropylene (PP) is an essential material of numerous applications in different industrial sectors, including packaging, construction, and automotive. Because the application of homopolypropylene (HPP) is limited by its relatively low impact strength and high embrittlement temperature, various types of impact copolymer PP (ICPP) that incorporate elastomers/rubbers into HPP to increase impact strength have been successfully commercialized. Crystallization kinetics of an isotactic HPP, an ICPP, and their composites were studied in this work understand the composites’ behaviors better. The Avrami-Jeziorny model was used to describe the crystallization process. For most samples, the Avrami exponent, n, was greater than 3, indicating the crystal grew in three dimensions with spherical geometry. However, the n value could drop below 3 when the ICPP content was 80 wt.% or higher and the cooling rate was 7.5°C/min or lower, implying that the crystals could grow in two dimensions and some lamella structures could be formed under those conditions. The nucleation activity increased with the increase of the ICPP content, demonstrating that the rubber phase in the ICPP acted as a nucleation agent and facilitated the nucleation process. The decrease in crystallization rate after the ICPP content exceeded 60 wt.% might be caused by the excessive amount of crystal nuclei induced by the high ICPP content, which caused strong crystal-crystal interactions and limited the crystal growth space. The nucleation activity and the n value showed high correlations to the mechanical and thermal properties of the materials. The quantitative study of the kinetics of crystallization in this work could be a helpful reference for manufacturing ICPP and HPP/ICPP mixtures.

Keywords: polypropylene, crystallization kinetics, Avrami-Jeziorny model, crystallization activation energy, Nucleation activity

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