Weight Ratio Of Monomers Research Articles

Synthesis of Hydrogel Based on Poly (Acrylic Acid–Co‐Vinyl Acetate) Grafted on Modified Recycled Cellulose for Use in Fertilizer Slow‐Release System

The aim of this work is a synthesis of suitable hydrogel to produce slow‐release fertilizer using recycled cellulose which is obtained from waste paper. For this purpose, initially, we extracted alpha cellulose from waste paper and modified it to obtain carboxymethyl cellulose (CMC). Then, the CMC was converted to a suitable hydrogel through in situ graft copolymerization of acrylic acid and vinyl acetate in the presence of methylene bisacrylamide as a crosslinker. The various factors that affect hydrogel synthesis, such as the amounts of CMC, monomers, initiator, and crosslinker, were evaluated. In the optimized formulation, the weight ratio of monomers to CMC is 7, the molar ratio of monomers to each other is 1, and the crosslinker is used as 3 molar percent of monomers. The products were characterized using Fourier transform infrared, thermal gravimetric analysis, and scanning electron microscope analyses. The swelling behavior of the synthesized hydrogels was evaluated in different environments, such as distilled water, tap water, salt water, and different pH levels. The swelling ratio increases with an increase in pH level. Between the synthesized hydrogels, the best one was selected for slow‐release fertilizer production and loaded with 20‐20‐20 fertilizer (NPK), and the release behavior was evaluated. In an alkaline pH, there was a long time for NPK release within a slow‐release medium and even after 361 h, the release process was continued. Also, the performance of the fertilizer‐loaded hydrogel in soil using water holding capacity and water retention ratio tests were evaluated.

Influence of the black seed oil modified epoxy resin/biscycloaliphatic epoxide monomer weight ratio on thermal properties of photocrosslinked coatings

AbstractThe influence of the black seed oil modified epoxy resin (EBSO)/monomer 3,4‐epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate (BCDE) weight ratio in the coatings based on the compounds and photoinitiator triarylsulfonium hexafluoroantimonate (TAS) on thermal properties of photocrosslinked coatings have been studied. The chemical structure of investigated UV‐cured coatings was characterized by IR spectrometric analysis. Their thermogravimetric (TG) and differential scanning calorimetry (DSC) behavior were determined by TG and DSC analysis, respectively. It was shown that the testing atmosphere had almost no effect to the form of TG, DTG curves and little effect on value of weight degradation of investigated coatings. The volatilization of low molecular weight compounds was observed in the range from room temperature to 360oC while the thermal degradation of the coatings occurred in the range from 360 to 455.5oC. The augmentation of the EBSO/BCDE weight ratio from 20/80 to 80/20 led to an increase of the degradation temperatures in the nitrogen atmosphere; extreme character of weight loss variation as well as the reduction of glass transition temperatures of the coatings from 79.8oC (Tg1) and 83oC (Tg2) to 36.8 (Tg1) and 38.9oC (Tg2), correspondingly.

Vat Polymerization by Three-Dimensional Printing and Curing of Antibacterial Zinc Oxide Nanoparticles Embedded in Poly(ethylene glycol) Diacrylate for Biomedical Applications.

Digital light processing (DLP) is a vat photopolymerization 3D printing technique with increasingly broad application prospects, particularly in personalized medicine, such as the creation of medical devices. Different resins and printing parameters affect the functionality of these devices. One of the many problems that biomedical implants encounter is inflammation and bacteria growth. For this reason, many studies turn to the addition of antibacterial agents to either the bulk material or as a coating. Zinc oxide nanoparticles (ZnO NPs) have shown desirable properties, including antibacterial activity with negligible toxicity to the human body, allowing their use in a wide range of applications. In this project, we developed a resin of poly(ethylene glycol) diacrylate (PEGDA), a cross-linker known for its excellent mechanical properties and high biocompatibility in a 4:1 weight ratio of monomers to water. The material's mechanical properties (Young's modulus, maximum elongation, and ultimate tensile strength) were found similar to those of human cartilage. Furthermore, the ZnO NPs embedding matrix showed strong antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S.A.). As the ZnO NPs ratio was changed, only a minor effect on the mechanical properties of the material was observed, whereas strong antibacterial properties against both bacteria were achieved in the case of 1.5 wt.% NPs.

Optimization of Cationic Polymerization of Vinyl Ether Monomers

In this study, the optimization of the cationic polymerization of vinyl ether monomers was carried out. The aim is to maximize the conversion of the monomers. A factorial design was used to evaluate the effects and interactions of three factors: photoinitiator concentration, the weight ratio of monomer and oligomer and alcohol concentration on the conversion of monomers. The optimal conditions from the desirable response are initiator concentration 5%, monomer/oligomer 1/1, and alcohol concentration 1.45%. Under these conditions, the conversion of 86.5% is obtained. The polymerization prepared under the optimized conditions verified the statistical experimental strategies' validity

Atomic force microscopy investigation of smart superabsorbent hydrogels based on carboxymethyl guar gum: Surface topography and swelling properties

Atomic force Microscopy (AFM) is commonly used to study various mechanical, functional, and electrical properties of materials at the nanoscale, as well as for characterizing the topography and surface properties. Up to our knowledge, this is the first investigation to study the surface properties of some carboxymethyl guar gum-based smart superabsorbent hydrogels before and after swelling. In this regard, three sets of modified carboxymethyl guar gum (CMGG) hydrogels were prepared via reaction with different weight ratios of acrylate monomers. The chemical composition of these hydrogels was assured via the IR spectroscopy and the morphology of the dry and swelled gels was studied via the ESEM. The swelling data were correlated with the chemical composition of the prepared hydrogels together with a detailed AFM study of their maps. The chemical modifications were also confirmed by a recent model of AFM. The data reveal that the highest swelling was achieved by C2 in which the weight ratio of acrylate monomers is twice that of guar gum (Qmax = 676 g g after 150 min) It was also found that the swelling capacity of all the prepared hydrogels decreases slightly from the first to the third swelling cycle. For instance, the swelling performance for C2 is as following: 767, 750 and 734 g g for the first, second and third cycles respectively. The data extracted from the AFM showed that surface roughness increases from 15.62 nm to 22.47 and the height rises from 11.2 nm to 43.9 nm as a result of chemical modification for guar gum into carboxymethyl guar gum.

Investigation into the role of the polymer in enhancing microwave-induced in situ amorphization

Microwave-induced in situ amorphization is an emerging technology to tackle the persistent stability issue of amorphous solid dispersions (ASDs) during manufacture and storage. The aim of this study was to introduce new effective polymeric carriers with diverse properties to microwave-induced in situ amorphization and to better understand their functions in relation to the final dissolution performance of microwaved tablets. Tablets composed of indomethacin (IND) and different polymers were compacted, stored at 75% relative humidity for at least 1 week and microwaved at 1000 W to induce amorphization. A series of polymers, polyvinylpyrrolidone/vinyl acetate copolymers (PVP/VA) of different monomer weight ratios displaying varyingproperties in functional groupratio, hygroscopicity, molecular weight (Mw), and glass transition temperature (Tg) of the polymer were used as model carriers. The results suggested that more than 90% of IND was amorphized after 20 mins microwaving in all 20% (w/w) drug loaded tablets except for IND:PVAc tablets presenting approx. 36% residual crystallinity. Among them, tablets composed of PVP/VA I-335 and PVP K30 achieved complete in situ amorphization upon microwaving. Further analysis indicated that the influencing factors, polymer Mw and Tg of moisture-plasticized polymer, played a major role in microwave-induced in situ amorphization. In in vitro dissolution study, ASDs containing PVP/VA I-535 with moderate hydrophilicity and 0.96 ± 1.92% IND residual crystallinity showed the most rapid and complete drug release among all formulations, presenting the most promising dissolution performance. Further study on the chemical stability of such formulation showed a statistically insignificant decrease of drug content after pre-conditioning and microwaving (P = 0.288 > 0.05).

Alkylacrylic-carboxyalkylacrylic random bipolymers as demulsifiers for heavy crude oils

This paper explains and analyses the process where two series of acrylic random bipolymers, based on alkyl acrylate/carboxyalkyl acrylate (KC) and alkyl acrylate/acrylic acid (KA), were prepared by means of emulsion polymerization technique. In both, the bipolymers’ monomers ratio was varied, while holding the more hydrophobic monomer in majority. The KC and KA bipolymers were characterized by nuclear magnetic resonance (NMR), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and size exclusion chromatography (SEC). Afterwards, demulsifying activity of the KC and KA bipolymers in two heavy crude oils was evaluated through bottle tests. According to the obtained results, the selection and determination of weight ratio of monomers have an important impact on the bipolymers efficiency to destabilize the water/crude oil emulsion. In both crude oils, KC bipolymer with a monomer ratio of K/C = 80/20 w/w showed the best demulsifying performance in comparison with KA bipolymer at the same weight ratio. Structure-activity parameters including partition coefficient (Log P), hydration energy (HE), molar refractivity (MR), and polarizability (α) were calculated for both bipolymers. The destabilization effectiveness of bipolymers of the water/crude oil interface was found to be related to the partition coefficient (Log P), which indicated a strong diffusion capacity of the bipolymer to traverse through the oil phase and destabilize the water/oil interface. Furthermore, higher values of molar refractivity and polarizability are preferable for higher water removal efficiency (WRE). Moreover, the structure–activity parameters, as well as the quantum parameters, specific characteristics of acrylic bipolymers and some physicochemical properties of the crude oil were deployed in the process to predict the water removal efficiency. E2 equation which accomplished the external validation acted as the resultant of the two equations, E1 and E2, that fulfilled the restriction for the internal validation of Q2 > 0.6. Predictive squared correlation coefficients (QF12,QF22, and QF32) and external validation metric parameter (rm2) were calculated based on E2. Consequently, the new alkylacrylic-carboxyalkylacrylic bipolymers, insusceptible to acid environment, showed significantly improved properties as emulsion breakers, drop coalescers, and clarifiers.

Relating the performance of sulfonated thin-film composite nanofiltration membranes to structural properties of macrovoid-free polyethersulfone/sulfonated polysulfone/O-MWCNT supports

Sulfonated thin-film composite nanofiltration (TFC NF) membranes were produced on macrovoid-free polyethersulfone/sulfonated polysulfone/oxidised multi-walled carbon nanotube (PES/SPSf/O-MWCNT) supports via an interfacial polymerisation method. The aqueous phase solution consisted of a mixture of piperazine (PIP) and 2,4-diaminobenzene sulfonic acid (2,4-DABSA) and the organic phase solution consisted of trimesoyl chloride (TMC). The TFC NF membranes fabricated on the PES/SPSf/O-MWCNT supports showed a 35% improvement in pure water flux with comparable salt rejections from those prepared on PES/SPSf supports. The presence of hydrophilic O-MWCNTs in the PES/SPSf supports resulted in the formation of a thin polyamide film on the surface of the support with enhanced water permeability and salt rejection. The addition of low monomer weight ratio of 2,4-DABSA in the diamine aqueous mixture led to the generation of sulfonated TFC NF membranes with superior membrane performance in terms of pure water permeability (30.2 L/m2·h·bar), monovalent/bivalent salt selectivity (αNaCl/Na2SO4 = 25.0) at low operating pressures (3 bar) and at salt concentrations in the range of brackish waters. Moreover, the fabricated sulfonated TFC NF membranes exhibited good antifouling properties against bovine serum albumin, with a flux recovery ratio of 96.4% obtainable after three cycles of fouling and cleaning. The performance of the sulfonated TFC NF membranes remained fairly stable over a 10-day period of pure water flux and Na2SO4 salt rejection testing. The fabricated sulfonated TFC NF membranes displayed promising features for use as pre-treatment membranes for lower-pressure water softening and desalination of brackish water.

Synthesis of organic‐inorganic hybrid nanocomposites based on the acrylate monomers and investigation of scratch resistance of these nanocomposites

AbstractOrganic‐inorganic hybrid nanocomposites can be used as polymer coatings in order to improve their scratch resistance. These nanocomposites consist of a polymer matrix that provides flexibility and lightweight, and inorganic nanoparticles that are responsible for high thermal stability and improving scratch resistance. In this study, the polymer matrix, methyl methacrylate‐butyl acrylate (MMA‐BA) copolymer, was synthesized by conventional emulsion polymerization. To get the highest conversion percentage of the copolymer, various parameters, including reaction temperature, weight ratio of monomers, mechanical stirrer speed, type and amount of initiator, total amounts, and weight ratio of emulsifiers were investigated. For the synthesis of nanocomposites, nanoparticles of titanium dioxide, iron oxide, silver sulfide, and modified and unmodified nanosilica were added to the copolymer with the highest conversion percentage. According to the data, the best conditions for the synthesis of a copolymer with the highest conversion percentage were as follows: weight ratio of MMA:BA = 60:40 with a total amount of 10 g monomers, mechanical stirrer speed of 250 rpm, thermal initiator water‐soluble ammonium persulfate with amount of 0.12 g, emulsifiers such as sodium dodecyl sulfate and Triton X‐100 with a weight ratio of 1:3 and a total value of 1 g, and the reaction temperature of 80°C. According to the results of thermal gravimetric analysis, the samples with the highest thermal stability were selected for nanoscratch test. Nanoscratch test results suggested that Ag2S nanocomposite including 0.03 g AgNO3 and 0.0072 g thiourea had the highest scratch resistance with the lowest coefficient friction (0.48) and the lowest coefficient scratch (0.113 μN–1/2). Chemical structures of synthesized compounds were confirmed by Fourier transform infrared spectroscopy. The morphology of synthesized Ag2S nanocomposite was investigated by scanning electron microscopy and energy dispersive X‐ray spectroscopy analyses.

Water compatible molecularly imprinted polymer for controlled release of riboflavin as drug delivery system

In this study, facile and green method for synthesis of imprinted material was introduced which subsequently applied for efficient delivery of Riboflavin (vitamin B2). Characterization of the prepared polymer was carried out by the Fourier Transform Infrared (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). The weight ratio of functional monomer to template over 5–20 W/W% was evaluated in order to find the best loading condition and subsequent release into synthetic biomimetic media namely simulated body fluid (SBF) and media including 1% NaCl solution, simulated gastric fluid (SGF) solution at pH 1.5 and the solution of 1% W/W Na2SO4. Under optimized condition, the highest value of released riboflavin was achieved at 1:20 ratio of riboflavin to polymer in NaCl (55.07%) media which providing that the body requirement about 5 days of this vitamin between minimum effective concentration (MEC) and maximum safe concentration (MSC) of Riboflavin in short release time (45 min). Moreover, the experimental data were fitted to Higuchi model in order to calculate Higuchi solubility constant.

Green synthesis of titanium dioxide/acrylamide-based hydrogel composite, self degradation and environmental applications

A green polymerization using TiO2 as an inorganic photoinitiator to synthesize titanium dioxide/poly[acrylamide-co-(acrylic acid)] hydrogel composite was successfully achieved. FTIR and SEM/EDXS characterizations indicated that the hydrogel composites were the crosslinked copolymer composed of acrylamide and acrylic acid in TiO2 particles. TiO2 hydrogel composites could adsorb up to 90% of 5 ppm methylene blue dye solution. Decolorization of methylene blue by the hydrogel composites was evaluated by colorimetry in term of K/S value. Approximately 83% of methylene blue was decolorized in 8 h by 5% TiO2 hydrogel composite and 90% decolorization in 8 h for 10% TiO2 hydrogel composites. The maximum color fading of methylene blue in the hydrogel composites at various UV irradiation times was observed by the slope of the linear region at different amounts of TiO2. It reveals that AMAA5050T10C1 gave the highest methylene blue fading of 91.6% with an R2 of 0.9999. The slope of 5 ppm Congo red in AM-T20-C1 adsorbent obeying a Pseudo-first order gave the highest dye removal of 44.8% with an R2 of 0.9572. This technique meets the criteria of green chemistry because the reaction does not need any organic photoinitiator or co-photoinitiator and the reaction takes place at room temperature. Congo red in polyacrylamide hydrogel composite containing 20% TiO2 obeyed a Pseudo-first order kinetics giving qe,exp = 2.22 mg g−1 (qe,cal = 2.24 mg g−1) while methylene blue in poly[acrylamide-co-(acrylic acid)] hydrogel composite at 50:50 monomer weight ratio containing 5% TiO2 followed a Pseudo-second order kinetics having qe,exp = 4.86 mg g−1 (qe,cal = 4.73 mg g−1). The rheological measurement of the TiO2/poly[arylamide-co-(acrylic acid)] hydrogel composites revealed a strong gel-like material and the self-degradation of the hydrogel composites evolved under UVA irradiation. TiO2/poly[(acrylamide)-co-(acrylic acid)] hydrogel composites synthesized in current work can be used as a model for both green synthesis of the hydrogel composites using an ionic photocatalyst, TiO2, and for degradation of organic dyes and self-degradation of the composites upon UV irradiation.

Accurately controlling the shell thickness in the core–shell microspheres with single silica core and poly (butyl acrylate) rubber shell via emulsion polymerization

The shell thickness of core–shell microspheres with a rigid core and soft rubber shell has been accurately controlled through the emulsion polymerization. When the amount of BA monomer and SiO2 is fixed, the morphology of core–shell microspheres with SiO2 core (Φ = 280 nm) and poly (butyl acrylate) (PBA) shell varies along with the emulsifier concentration (Ce). If Ce is lower than a low critical value Cel, aggregated micelles with multiple SiO2 cores are formed. And while Ce is higher than an upper critical value Ceu, isolated PBA micelles without SiO2 core appear in the system. For a given amount of BA monomer and SiO2 core, core–shell particles with single SiO2 core can only be obtained at Cel Ʃ > ƩLC), the rubber shell thicknesses of core–shell particles with single SiO2 core can vary from 8 to 57 nm along with the weight ratio of BA monomer to SiO2 that increases from 1:10 to 1:1.

Preparation of microencapsulated phase change materials (MEPCM) for thermal energy storage

Microencapsulated phase change materials (MEPCM) could be used for energy saving applications in buildings due to their relatively high energy storage capacities at constant temperature, which could passively reduce peak cooling loads in summer. In this study, poly(methyl methacrylate-co-methacrylic acid) (PMMA-MAA) was used as a shell material to fabricate MEPCM by crosslinking methyl methacrylate (MMA) and methacrylic acid (MAA) through in-situ suspension-like polymerization method. The effects of initiator weight percentage and the ratio of shell monomers for the preparation of MEPCM were also investigated. The experimental results showed that the best MEPCM sample was achieved with a shell monomer weight ratio of 80% MMA : 20% MAA and thermal initiator of 1 wt%. Differential scanning calorimetric (DSC) analysis also showed a latent heat value for the best sample as 170 kJ/kg with a melting temperature of 23.68°C which makes these materials suitable for application in residential buildings. Meanwhile, the core material contents and encapsulation efficiencies were calculated according to the measured results of the DSC. Finally the thermogravimetric (TG) analysis on the samples showed very good thermal stability behaviours ranging between 162.3°C and 204.4°C and therefore satisfies the environmental requirements for most applications.

Micelle or polymersome formation by PCL-PEG-PCL copolymers as drug delivery systems

Poly(ε-caprolactone)-b-poly(ethylene glycol)-b-poly(ε-caprolactone) (PCL-b-PEG-b-PCL, PCEC) triblock copolymers have been widely investigated in last several decades. Here, by altering the weight ratio of monomers in ring-opening polymerization, a series of PCEC triblock copolymers with varying hydrophobicity were synthesized, which were characterized by FTIR, 1H NMR, GPC and DSC. When PCEC copolymers with different weight ratios of PCL/PEG were dispersed in different aqueous solutions, they could self-assemble and form two distinctive nanoparticular structures: micelles or polymersomes. We then chose paclitaxel (PTX) as the model drug and encapsulate PTX into PCEC polymeric micelles and polymersomes. The physicochemical characterizations of the nanoparticles such as morphology, the size and distribution, zeta potential, drug loading content, and encapsulation efficiency were also performed. Our results showed that polymeric micelles or polymersomes from PCEC both displayed narrow size distributions and could achieve high drug loading efficiencies. In vitro cellular uptake results suggested that Nile Red loaded polymeric micelles or polymersomes displayed more internalization after 24h incubation than those after 4h incubation. These findings suggest that polymeric micelles and polymersomes based on PCL-b-PEG-b-PCL copolymers have great potential to effectively delivery hydrophobic drugs.

Graft copolymerization and characterization of styrene with chitosan via radical polymerization

In this study, styrene was successfully grafted onto chitosan by conventional free radical polymerization technique, using potassium persulphate (KPS) as the initiator. The effect of various reaction conditions including chitosan:monomer weight ratio, polymerization temperature, reaction time and concentration of initiator were studied. The highest percentage grafting (G %) 180% was found at 1:4 chitosan:styrene weight ratio, 0.4 g KPS and 70 o C reaction temperature. Fourier transform infrared spectroscopy (FTIR) results showed the presence of polystyrene peaks, indicating the success of the grafting procedure. Thermogravimetric analyses (TGA) revealed that the thermal stability of the prepared copolymer is higher than that of chitosan alone. M w and M n of the isolated polystyrene from the graft copolymer were found to be 9.5249 × 10 4 g/mol and 3.0755 × 10 4 g/mol, respectively, with a polydispersity index of 3.1 Keywords: Biomaterials, Chitosan, Grafting, Polymers, Polystyrene, Potassium persulphate

Removal of metal ions from aqueous solutions by chitosan-g-itaconic acid/hydrophilic nanoclay nanocomposites

In this work, chitosan-g-itaconic acid copolymer nanocomposites containing nanoclay (1–5%, weight ratio) were synthesized using cerium (IV) ammonium nitrate as initiator. The optimum reaction conditions were identified as chitosan/itaconic acid monomer weight ratio of 3/9 and initiator concentratio n of 0.003 mol/L. These reaction conditions were used as preparation of chitosan-g-itaconic acid copolymer nanocomposites. XRD analysis and grafting percentage determination were used for characterization of nanocomposites. XRD patterns of nanocomposites indicate that clay sheets are exfoliated. Grafting percentages of chitosan-g-itaconic acid copolymers were determined as about 30%. Chitosan-g-itaconic acid nanocomposites were used for the removal of heavy metal ions from aqueous solutions. The results showed that the second-order kinetic model was suitable for the adsorption of Cu(II) and Pb(II) onto chitosan-g-itaconic acid nanocomposites. The equilibrium adsorption data have been evaluated using Langmuir, Freundlich, Temkin, Dubinin-Raduskevich and Redlich–Peterson models. Langmuir isotherm model (Type 1) and Redlich–Peterson isotherms are the best-fit models forthe adsorption process in this study.

Effect of Acrylic Content on the Properties of the Polyurethane/Polyacrylate Composite Emulsion

A polyurethane/polyacrylate (PUA) composite emulsion was synthesized by using polyurethane (PU) as seeds with soap-free emulsion polymerization, in which methyl methacrylate (MMA) and butyl acrylate (BA) were used as main acrylic monomers. The effect of acrylic contents and “stiff” and “soft” weight ratio of acrylic monomers on the properties of the films were investigated. The Fourier transform infrared (FTIR) results showed that acrylic monomers were involved in the emulsion copolymerization. The optimum composition of PUA composite formation was obtained when the polyacrylate (PA) content was 20%, in which the weight ratio of MMA and BA was 2/1. With the increment of PA content, the decomposition temperature increased.

Nitrogen-doped carbon with mesoporous structure as high surface area catalyst support for methanol oxidation reaction

Mesoporous nitrogen-doped carbon (MNC) with a high surface area has been synthesized via carbonizing polyaniline using silica nanoparticles as template. The more silica nanoparticles, the smaller the micropore surface area is and the larger the mesoporous surface area is. Moreover, with an increase in the amount of silica nanoparticles, the electrocatalytic activity of Pt/MNC catalysts shows a downward trend after an intimal increase, and the Pt/MNC-1/6 (with the weight ratio of aniline monomer to silica nanoparticles of 1/6) catalyst has the highest activity, ascribed to the optimal Pt nanoparticles size, which is closely related to the pore structure of the support. In addition, the electrocatalytic activity and stability of Pt/MNC-1/6 catalyst are significantly superior to that of Pt/nitrogen-doped carbon (Pt/CNx) catalyst. For the same electrocatalytic activity, the Pt loading of Pt/MNC-1/6 catalyst is reduced by 33.3% compared to the Pt/CNx catalyst. The high electrocatalytic activity originates from the introduction of mesoporous structures that can facilitate mass transfer and improve the dispersion of Pt nanoparticles. Furthermore, the Ostwald ripening behavior of Pt nanoparticles is limited in the mesoporous structure of MNC-1/6, which weakens the aggregation effect of Pt nanoparticles during the electrocatalytic processes, thus enhancing the electrocatalytic stability of the catalyst.

Synthesis of versatile poly(PMMA‐b‐VI) macromonomer‐based hydrogels via infrared laser ignited frontal polymerization

ABSTRACTIn this work, poly((PMMA‐b‐VI)‐co‐AA) (MMA = methyl methacrylate; VI = 1‐vinylimidazole; AA = acrylic acid) hydrogels and poly((PMMA‐b‐VI)‐co‐AA)/TPU (TPU = thermoplastic polyurethane) IPN (interpenetrating polymer networks) hydrogels have been fabricated via versatile infrared laser ignited frontal polymerization by using poly(PMMA‐b‐VI) macromonomer as the mononer. The frontal velocity and Tmax (the highest temperature that the laser beam detected at a fixed point) can be adjusted by varying monomer weight ratios, the concentration of BPO (BPO = benzoyl peroxide) and the amount of TPU. Moreover, the addition of TPU enhances the reactant viscosity to suppress the “fingering” of frontal polymerization (FP) and decrease Tmax of the reaction, providing a new inert carrier (TPU) to assist FP. Through the characterization of Fourier transform‐infrared spectroscopy (FT‐IR), scanning electron microscope (SEM), and differential scanning calorimetry (DSC), the desired structure can be proved to exist in the IPN hydrogels. Furthermore, poly((PMMA‐b‐VI)‐co‐AA)/TPU IPN hydrogels possesses more excellent mechanical behaviors than hydrogels without IPN structure. Besides, the poly((PMMA‐b‐VI)‐co‐AA) hydrogels present splendid sensitive properties toward substances of different flavor including sourness (CA, citric acid or GA, gluconic acid), umami (SG, sodium glutamate), saltiness (SC, sodium chloride), sweetness (GLU, glucose), enabling their potential as artificial tongue‐like sensing materials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1210–1221

Development of Green Dual Polymers for Antibacterial Applications

In this article, we report on the antibacterial properties of a novel antimicrobial poly(citric acid-co-curcumin) polymer system that was prepared by a catalyst–free polyesterification process. The dual polymer of poly(citric acid-co-curcumin) was synthesized by varying the weight ratio of citric acid and curcumin monomers. Details of the synthesis, spectral (Fourier transform infrared, ultraviolet), thermal stability (Thermogravimetric analyses), and the morphological (Scanning electron microscopy/energy dispersive spectroscopy) characterization of dual polymers are presented in this scientific article. The UV–visible spectrometry was used to confirm the copolymerization of curcumin dispersion in the dual polymer systems. The presence of functional groups of copolymers was confirmed by Fourier transform infrared spectroscopy. The thermogravimetric analysis results indicated that poly(citric acid-co-curcumin) have a thermal stability up to 225°C. The ratios used were 1:0.25, 1:0.5, 1:0.75, and 1:1 and their antibacterial properties were studied with respect to their activity on gram-positive and gram-negative bacteria. This dual polymer was inoculated onto a Petri dish and its ability to inhibit the growth of Escherichia coli, Staphylococcus, Bacillus subtilis, Candida albicans (fungus), and Micrococcus luteus was evaluated using the bacterial disc method. Results indicated inhibition properties to increase with increasing curcumin content and the dual polymer with highest curcumin content showed excellent antimicrobial activities against both gram-negative and gram-positive microorganisms. Hence, it was clear that the developed dual polymers may be effectively used for antibacterial applications such as wound dressing.