Showing papers on "Methacrylic acid published in 2019"

pH-responsive CAP-co-poly(methacrylic acid)-based hydrogel as an efficient platform for controlled gastrointestinal delivery: fabrication, characterization, in vitro and in vivo toxicity evaluation

Abstract: Cellulose acetate phthalate-based pH-responsive hydrogel was synthesized for fabrication of polymeric matrix tablets for gastro-protective delivery of loxoprofen sodium. Cellulose acetate phthalate (CAP) was cross-linked with methacrylic acid (MAA) using free radical polymerization technique. Fourier transform infrared (FTIR) spectra confirmed the formation of cross-linked structure of CAP-co-poly(methacrylic acid). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the thermal stability of polymeric networks, and scanning electron microscopy (SEM) and energy-dispersive X-ray spectrum (EDS) images unveiled that the prepared formulations were porous in nature and thus the developed formulations had shown better diffusibility. Swelling and in vitro drug release was performed at various pHs and maximum swelling and release was obtained at pH 7.4, while swelling and release rate was very low at pH 1.2 which confirmed the pH-responsive behavior of CAP-co-poly(MAA). CAP-co-poly(MAA) copolymer prevents the release of loxoprofen sodium into the stomach due to reduced swelling at gastric pH while showing significant swelling and drug release in the colon. Cytotoxicity studies revealed higher biocompatibility of fabricated hydrogel. Acute oral toxicity studies were performed for the evaluation and preliminary screening of safety profile of the developed hydrogels. Matrix tablets were evaluated for release behavior at simulated body pH. The investigations performed for analysis of hydrogels and fabricated matrix tablets indicated the controlled drug release and gastro-protective drug delivery of CAP-co-poly(MAA) hydrogels and pH-sensitive matrix tablets for targeted delivery of gastro-sensitive/irritative agents.

β-Cyclodextrin based pH and thermo-responsive biopolymeric hydrogel as a dual drug carrier

Abstract: Herein, a novel biocompatible and stimuli-responsive network gel has been developed by grafting and crosslinking poly(N-isopropyl acrylamide) and poly(methacrylic acid) on cyclic oligosaccharide β-cyclodextrin [β-CD-cl-(PNIPAm-co-PMAc)]. Various characterizations (such as NMR spectroscopy, CHN analysis, LCST measurement, and FESEM analysis) have been performed to confirm the formation of copolymer. Swelling characteristics reveal that the developed hydrogel demonstrates dual responsive behaviour (pH and thermo-responsive). The copolymer shows viscoelastic properties and is characterized with excellent yield stress as well as compressive stress. The network hydrogel displays a non-cytotoxic nature towards MG-63 cell lines. The simultaneous in vitro release of metronidazole and ofloxacin from the gel endorses that it released both the colonic drugs simultaneously at the preferred pH (colonic pH 7.4) and body temperature (37 °C) at a desired rate. Finally, the β-CD-cl-(PNIPAm-co-PMAc) gel is probable to be promising for targeted and sustained release of metronidazole and ofloxacin as is obvious from in vivo analysis.

Structure-property relationships for polycarboxylate ether superplasticizers by means of RAFT polymerization.

Abstract: Hypothesis Polycarboxylate ether (PCE) comb-copolymers are widely used as water reducing agents in the concrete industry while maintaining a high fluidity via the polymer adsorption to the cement particles. PCE copolymers with a broad range of structures are well established by Free radical polymerization, however, understanding the structure-property relationship is still complex due to the high polydispersity of PCE copolymers prepared by conventional polymerization. The influence of different structural parameters using well-defined polymeric structures is yet to be explored. Experiments In this study, two different types of comb-like random copolymers, namely polycarboxylate ether (PCE; poly(oligo(ethylene glycol) methyl ether methacrylate/methacrylic acid)) and polysulfonate ether (PSE; poly(oligo(ethylene glycol) methyl ether acrylate/sodium 4-styrenesulfonate)), were synthesized by RAFT polymerization to enable the synthesis of polymers with controlled features. The effect of charge types and side chain lengths on the adsorption, rheology, and dispersing ability of cement pastes have been studied. Findings RAFT polymerization could be used to prepare PCE random copolymers with good control over the polymer molecular weight and narrow polydispersity (Đ

Development the sorption behavior of nanocomposite Mg/Al LDH by chelating with different monomers

Abstract: Methacrylic acid, acetonitrile, dimethylsulfoxide and 1,4 dioxane intercalated Mg–Al layered double hydroxide (LDH) was made by the use of coprecipitation and the chelation techniques. The elimination of strontium, nitrate, and borate in polluted solution was scrutinized. The adsorption of Sr2+, NO3−, and B4O72− on methacrylate intercalated Mg–Al LDH (methacrylic acid (MAA)-Mg-Al LDH) proved that the adsorption process was spontaneous and increased randomness in the system. The equipped LDHs were performed by HNMR, scanning electron microscopy (SEM), thermogravemitric analysis (TGA), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS). It was established that different monomer types could intercalate inside an interlayer of the Mg–Al LDH. Methacrylic acid-intercalated Mg–Al LDH can effectively adsorb strontium, nitrate, and borate in aqueous solutions more effectively than other prepared LDHs. The dependability of the (MAA)-Mg-Al LDH was premeditated by iterating consecutive adsorption/desorption cycle.

Molecularly Imprinted Polymers with Dual Template and Bifunctional Monomers for Selective and Simultaneous Solid-Phase Extraction and Gas Chromatographic Determination of Four Plant Growth Regulators in Plant-Derived Tissues and Foods

Abstract: A highly selective and sensitive molecularly imprinted polymer (MIP)-based solid-phase extraction (SPE) combined with gas chromatographic (GC) detection method was developed for the simultaneous isolation and determination of four plant growth regulators (PGRs) including indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), 1-naphthaleneacetic acid (NAA), and 2,4-dichlorophenoxyacetic acid (2,4-D) in plant tissues, fruits, and vegetables. The MIP composites, synthesized by application of dual template molecules (IAA and 2,4-D) and bifunctional monomers β-cyclodextrin (β-CD) and methacrylic acid (MAA), were characterized by FTIR, BET, XRD, SEM, and TGA techniques. The effects of the amount of adsorbent, sample pH, and eluent solvents on the SPE performance were investigated. Under the optimal SPE condition, the β-CD/MAA-MIPs exhibited higher selective capability and greater adsorption capacity toward target PGRs when compared with commercial SPE adsorbents, single template, and functional monomer MIPs. In addition, the stability and reusability studies demonstrated that the synthesized β-CD/MAA-MIPs were capable for reutilization with stable performance in sample pretreatment process. Finally, the proposed β-CD/MAA-MIPs-SPE-GC technique was successfully applied to analyze the interested PGRs in different plant tissues, fruits, and vegetable samples.

Life Cycle Assessment for the Organocatalytic Synthesis of Glycerol Carbonate Methacrylate.

Abstract: Bifunctional ammonium and phosphonium salts have been identified as potential organocatalysts for the synthesis of glycerol carbonate methacrylate (GCMA). Three of these catalysts showed high efficiency and allowed the conversion of glycidyl methacrylate with CO2 to the desired product in >99 % conversion and selectivity. Subsequently, immobilized analogues of selected catalysts were prepared and tested. A phenol-substituted phosphonium salt on a silica support proved to be a promising candidate in recycling experiments. The same catalyst was used in 12 consecutive runs, resulting in GCMA yields of up to 88 %. Furthermore, a life cycle assessment was conducted for the synthesis of GCMA starting from epichlorohydrin (EPH) and methacrylic acid (MAA). For the functional unit of 1 kg GCMA, 15 wt % was attributed to the incorporation of CO2 , which led to a reduction of the global warming potential of 3 % for the overall process.

Fabrication and binding characterization of ion imprinted polymers for highly selective Co2+ ions in an aqueous medium

Abstract: A new sorbent material for cobalt ion extraction was synthesized using molecular imprinting technology for determination of cobalt ions in an aqueous medium. Two types of imprinted polymers were synthesized using different functional monomers (methacrylic acid and 4-vinylpyridine) in the presence of dipicolinic acid for complex forming with cobalt ion. The imprinted polymers were cross-linked by ethylene glycol dimethacrylate via bulk polymerization procedure. Simultaneously, the non-imprinted polymers were prepared as controlled samples. The effects of sample dosage and time taken were investigated through an adsorption isotherm study. The affinity of Co2+ ions for the imprinted polymer based on methacrylic acid monomer was stronger than 4-vinylpyridine monomer as proven by higher adsorption capacity and increased selectivity toward Co2+ ions over the competing metal ions. Therefore, the coordinate mode of cobalt-dipicolinic acid, along with the functionality of monomers, led to the production of highly selective recognition toward the cobalt ions. This synergistic effect seems logical as each component contributed to the overall imprinting process. The adsorption isotherm experiment indicated that the Freundlich isotherm model yields a better fit toward the equilibrium adsorption data, while the Pseudo-second-order equation is the appropriate model describing the kinetic sorption behavior of the polymers.

Selective catalytic decarboxylation of biomass-derived carboxylic acids to bio-based methacrylic acid over hexaaluminate catalysts

Abstract: Methacrylic acid (MAA) is a polymer molecular constituent in related plastics industry, presently produced from supplied fossil-based resources. This scientific paper reports an environmentally-benign catalytic process for the production of MAA via the decarboxylation of carboxylic groups. Various hexaaluminate catalysts were synthetized examined and tested to achieve the maximum amount yield of MAA from biomass derived carboxylic acids. Active phases on catalyst surfaces were characterized with numerous microscopic, spectroscopic and chemi-/physi-sorption techniques. Among hexaaluminate catalysts, the highest selectivity towards MAA (50%) was accomplished over barium hexa-aluminate at relatively mild reaction conditions (3 h, 250 °C and 20 bar). In addition, the catalyst could be reused four times without the loss of activity. A plausible pathway mechanism was also hypothesized. The high catalytic activity of BHA catalyst compared to the other tested catalysts believed to be associated with its peculiar layered structure, surface defect sites, moderate basicity and high surface area. The newly developed catalyst and corresponding process avoid the use of expensive noble or transition metals and corrosive alkalis. Overall, the development of catalysis presents a step forward in the synthesis of a sustainable structural constituent.

Film formation of high Tg latex using hydroplasticization: Explanations from NMR relaxometry

Abstract: The film formation of acrylic latex dispersions, containing different amounts of carboxylic acid functional groups by the incorporation of methacrylic acid (MAA), was studied with GARField 1H NMR at various relative humidities (RH). Polymer particles with glass-transition temperatures in the range from 26 to 50 °C formed films at room temperature because of hydroplasticization. It was found that with an increased drying rate due to lower RH, the evaporation flux of water was limited by the latex polymer. Only in the second stage of drying this phenomenon was more obvious with increasing MAA content. 1H NMR relaxometry was used to study the change of hydrogen mobilities during film formation and hardening of the films. This showed that the drying rate itself had no impact on the hydrogen mobility in the latex films as measured via the T2 relaxation time. Hydrogen mobilities of water and the mobile polymer phase only significantly decrease after most water has evaporated. This implies that the rigidity of the polymers increases with the evaporation of water that otherwise plasticizes the polymer through hydrogen bonding with the carboxylic acid groups. This hardening of the polymer phase is essential for applications in a coating. The hydrogen mobilities were affected by the MAA concentration. Densities of mobile hydrogens increase with increasing MAA content. This is expected if the mobile protons are contained in the MAA groups. The result thus confirms the role of carboxylic acid groups in hydrogen bonding and plasticization of the copolymers. Hydrogen mobilities, however, decrease with increasing MAA content, which is hypothesized to be caused by the formation of dimers of carboxylic acid groups that still hold water. They still enable short-range polymer hydrogen mobility due to hydroplasticization but limit long-range polymer mobility due to interaction between the carboxylic acid groups.

Esterification of Methacrylic Acid with Methanol: Process Optimization, Kinetic Modeling, and Reactive Distillation

Abstract: The esterification of methacrylic acid with methanol catalyzed by NKC-9 resin (a cation-exchange resin with sulfonate groups) was conducted in a stainless stirred batch reactor. The effects of cata...

Unusual Radical Copolymerization of Suprabulky Methacrylate with N-Hydroxysuccinmide Acrylate: Facile Syntheses of Alternating-Rich Copolymers of Methacrylic Acid and N-Alkyl Acrylamide

Abstract: In this work, we provide a facile methodology to synthesize AB alternating-rich copolymers made of methacrylic acid (MAA) and alkyl acrylamide units. An extremely bulky tert-alkyl methacrylate carr...

Effect of a Competitive Solvent on Binding Enthalpy and Chain Intermixing in Hydrogen-Bonded Layer-by-Layer Films

Abstract: This work is focused on the effect of a small-molecule/hydrogen-bonding competitor on the heat of complexation of hydrogen-bonding polymers in aqueous solutions, as well as on deposition of these molecules within layer-by-layer (LbL) films. Specifically, binding between poly(methacrylic acid) (PMAA) and poly(vinylpyrrolidone) (PVP) under acidic conditions in the presence of dimethyl sulfoxide (DMSO) has been explored. Isothermal titration calorimetry showed that with increasing concentration of DMSO in aqueous solution, the positive enthalpy of formation of PMAA/PVP complexes decreased and switched sign at ∼25 vol % DMSO. This change is interpreted as a transition from endothermal association between PMAA and PVP in water, driven by release of solvation water molecules, to exothermic association driven by the enthalpy of interpolymer hydrogen bonding. This switch is interpreted as destruction of polymer hydration shells by DMSO molecules. The content of DMSO also strongly impacted the growth of LbL films....

Ultra-Strong and Fast Response Gel by Solvent Exchange and Its Shape Memory Applications

Abstract: Solvent response gels were synthesized by copolymerization of hydrophobic butyl methacrylate (BMA) and hydrophilic methacrylic acid (MAA) with cross-linker N,N′-methylenebis(acrylamide) (BIS) in a ...

Development and in vitro evaluation of (β-cyclodextrin-g-methacrylic acid)/Na + -montmorillonite nanocomposite hydrogels for controlled delivery of lovastatin

Abstract: Background: Hyperlipidemia is the elevation of low density lipoprotein levels resulting in fat deposites in arteries and their hardening and blockage. It is the leading cause of several life threatening pathological conditions like hypertension, cardiovascular diseases, diabetes etc. Purpose: The objective of this study was to prepare and optimize nontoxic, biocompatible β-CD-g-MAA/Na+-MMT nanocomposite hydrogels with varying content of polymer, monomer and montmorillonite. Moreover, lipid lowering potentials were determined and compared with other approaches. Methods: β-CD-g-MAA/Na+-MMT nanocomposite hydrogels (BM-1 to BM9) were prepared through free radical polymerization by using β-CD as polymer, MAA as monomer, MBA as crosslinker and montmorillonite as clay. Developed networks were evaluated for FTIR, DSC, TGA, PXRD, SEM, sol-gel fraction (%), swelling studies, antihyperlipidemic studies and toxicity studies. Results: Optimum swelling (94.24%) and release (93.16%) were obtained at higher pH values. Based on R2 and "n" value LVT release followed zero order kinetics with Super Case II transport release mechanism, respectively. Tensile strength and elongation at break were found to be 0.0283MPa and 94.68%, respectively. Gel fraction was between 80.55 - 98.16%. Antihyperlipidemic studies revealed that LDL levels were markedly reduced from 522.24 ± 21.88mg/dl to 147.63 ± 31.5mg/dl. Toxicity studies assured the safety of developed network. Conclusion: A novel pH responsive crosslinked network containing β-CD - g - poly (methacrylic acid) polymer and MMT was developed and optimized with excellent mechanical, swelling and release properties and lipid lowering potentials.