Showing papers on "Methacrylic acid published in 2018"

A Tough and Stiff Hydrogel with Tunable Water Content and Mechanical Properties Based on the Synergistic Effect of Hydrogen Bonding and Hydrophobic Interaction

Abstract: Hydrogels are usually recognized as soft and weak materials, the poor mechanical properties of which greatly limit their applications as structural elements. Designing of hydrogels with high strength and high modulus has both fundamental and practical significances. Herein we report a series of tough, stiff, and transparent hydrogels facilely prepared by copolymerization of 1-vinylimidazole and methacrylic acid in dimethyl sulfoxide followed by solvent exchange to water. The equilibrated hydrogels with water content of 50–60 wt % possessed excellent mechanical properties, with tensile breaking stress, breaking strain, Young’s modulus, and tearing fracture energy of 1.3–5.4 MPa, 40–330%, 20–170 MPa, and 600–4500 J/m2, respectively. These tough hydrogels were also stable over a wide pH range (2 ≤ pH ≤ 10), resulting from the formation of dense and robust hydrogen bonds between imidazole and carboxylic acid groups. Moreover, the water content and mechanical properties of one gel can be adjusted over a wide r...

Catalysis for the synthesis of methacrylic acid and methyl methacrylate

Abstract: Methyl methacrylate (MMA) is a specialty monomer for poly methyl methacrylate (PMMA) and the increasing demand for this monomer has motivated industry to develop clean technologies based on renewable resources. The dominant commercial process reacts acetone and hydrogen cyanide to MMA (ACH route) but the intermediates (hydrogen cyanide, and acetone cyanohydrin) are toxic and represent an environmental hazard. Esterification of methacrylic acid (MAA) to MMA is a compelling alternative together with ethylene, propylene, and isobutene/t-butanol as feedstocks. Partially oxidizing isobutane or 2-methyl-1,3-propanediol (2MPDO) over heteropolycompounds to MAA in a single-step is nascent technology to replace current processes. The focus of this review is on catalysts and their role in the development of processes herein described. Indeed, in some cases remarkable catalysts were studied that enabled considerable steps forward in both the advancement of catalysis science and establishing the basis for new technologies. An emblematic example is represented by Keggin-type heteropolycompounds with cesium and vanadium, which are promising catalysts to convert isobutane and 2MPDO to MAA. Renewable sources for the MMA or MAA route include acetone, isobutanol, ethanol, lactic, itaconic, and citric acids. End-of-life PMMA is expected to grow as a future source of MMA.

General Strategy for the Preparation of Stable Luminous Nanocomposite Inks Using Chemically Addressable CsPbX3 Peroskite Nanocrystals

Abstract: The potential optoelectronic applications of perovskite nanocrystals (NCs) are primarily limited by major material instability arising from the ionic nature of the NC lattice. Herein, we introduce a facile and effective strategy to prepare extremely stable CsPbX3 NC–polymer composites. NC surfaces are passivated with reactive methacrylic acid (MA) ligands, resulting in the formation of homogeneous nanocubes (abbreviated as MA-NCs) with a size of 14–17 nm and a photoluminescence quantum yield above 80%. The free double bonds on the surface then serve as chemically addressable synthetic handles, enabling UV-induced radical polymerization. Critically, a bromide-rich environment is developed to prevent NC sintering. The composites obtained from copolymerizing MA-NCs with hydrophobic methyl methacrylate and methacrylisobutyl polyhedral oligomeric silsesquioxane monomers exhibit enhanced properties compared to previously reported encapsulated NCs, including higher quantum yields, remarkable chemical stability t...

Structural, Optical and Thermal Characterizations of PVA/MAA:EA Polyblend Films

Abstract: Films of polyvinyl alcohol (PVA), Methacrylic Acid - Ethyl Acrylate (MAA:EA) copolymer and their blends PVA:MAA:EA of composition 80:20, 60:40, 50:50, 40:60, 20:80 (wt %) were prepared by using the solution cast technique. The prepared films were investigated by structural, optical and thermal studies. X-ray diffraction (XRD) scans revealed the semicrystalline nature of the blends for lower concentrations of PVA up to 60 wt % and the amorphous nature for higher ones. Fourier transform infra-red spectroscopy (FTIR) of blend samples indicates that there is a compatibility between PVA and MAA:EA copolymers through the formation of hydrogen-bonding between their polar groups.SEM image of polymer blend suggested the presence structural reorganization of polymer chains. UV-Visible spectral analysis revealed that the intensity of the shoulder around 271 nm decreases with increasing MAA:EA content. In DSC analysis, a single glass transition temperature for each blend was observed, which supports the existence of compatibility of such systems. From the observed results, 50:50 (wt %) PVA/MAA:EA is found to be the optimum blending ratio.

Control of the Alternating Sequence for N‐Isopropylacrylamide (NIPAM) and Methacrylic Acid Units in a Copolymer by Cyclopolymerization and Transformation of the Cyclopendant Group

Abstract: An alternating copolymer of methacrylic acid and N-isopropyl acrylamide (NIPAM) was synthesized by selective cyclopolymerization of a special divinyl monomer and transformation of repeating cyclo-units in the resultant cyclopolymer. Crucial to the breakthrough is the monomer design in view of two types of cleavable bonds (3° ester and activated ester) in the pendant group of the monomer and the lower reactivity ratio of the two double bonds (methacrylate and electron-poor acrylate) for the polymerizable groups. The thus-obtained cyclopolymer was transformed into the alternating copolymer by transformation of the activated ester into amide by isopropyl amine and cleavage of the 3° ester by trifluoroacetic acid. The resultant copolymer showed thermal and pH response in aqueous solution that was different from the 1:1 random copolymer as well as the homopolymers.

Synthesis and Characterization of Biodegradable Hydrogels for Oral Delivery of 5-Fluorouracil Targeted to Colon: Screening with Preliminary In Vivo Studies

Abstract: In this communication, we developed a thermally stable, biocompatible, and colonically degradable hydrogel-based device [pectin-co-poly(MAA)] for oral delivery of 5-fluorouracil (5-FU) to treat colon cancer with minimal upper gastrointestinal invasion. Toward this end, ethylene glycol dimethacrylate (EGDMA) cross-linked hydrogels of pectin were synthesized. Methacrylic acid (MAA) was grafted to impart pH-responsive character, whereas benzoyl peroxide (BPO) was applied for simultaneous grafting and cross-linking polymerization. The hydrogels were characterized by Fourier transform infrared , thermogravimetric analysis, differential scanning calorimetry, and X-ray diffractometry. Scanning electron microscopic photographs were taken to analyze the surface morphology. Swelling behavior was analyzed to assess better performance of biodegradable hydrogels for optimized loading and release of the drug targeted to the colon. Gel fraction, swelling ratio, diffusion coefficient, drug loading, and cumulative release increased with an increase of pectin ratio and decreased with an increase of MAA and EGDMA ratio. Strategically, hydrogels with higher amounts of pectin were prepared for complete degradation in the colon. Our investigations indicate that pectin-co-poly(MAA) hydrogel is a suitable delivery system developed for oral delivery of the drug targeted to the colon.

Development and characterization of pH-responsive polyethylene glycol-co-poly(methacrylic acid) polymeric network system for colon target delivery of oxaliplatin: Its acute oral toxicity study

Abstract: An oral route of administration is a most acceptable route for a patient, so we designed chemically cross-linked polyethylene glycol-co-poly(methacrylic acid) oral hydrogels (PEGMA 4000) by free radical polymerization method for pH-responsive colon target delivery of oxaliplatin (OXP) Polyethylene glycol (PEG 4000) was cross-linked chemically with methacrylic acid (MAA) in distilled water Ammonium peroxodisulfate (APS) and N, N-methylene bisacrylamide (MBA) were used as initiator and cross-linker respectively OXP was loaded in prepared hydrogels FTIR, DSC, TGA, SEM, and XRD were conducted for characterization of developed hydrogels which endorsed the formation of new polymeric network The pH-sensitive behavior of hydrogels was observed by swelling dynamics and equilibrium swelling ratio at low (12) and higher pH (74) Toxicity study was also conducted on rabbits to evaluate toxicity and biocompatibility of developed carrier system to biological system Hydrogels with higher PEG 4000 concentration showed maximum swelling and higher drug loading at 74 pH Toxicity study confirmed the developed hydrogels as non-toxic and biocompatible for biological system Resultantly, these hydrogels can become an excellent candidates for colon targeting of OXP to treat colorectal cancer with no toxicity

Uptake of heavy metal ions from aqueous media by hydrogels and their conversion to nanoparticles for generation of a catalyst system: two-fold application study

Abstract: Poly(methacrylic acid) (P(MAA)), poly(acrylamide) (P(AAm)) and poly(3-acrylamidopropyltrimethyl ammonium chloride) (P(APTMACl)) were synthesized as anionic, neutral and cationic hydrogels, respectively. The synthesized hydrogels have the ability to be used as absorbents for the removal of selected heavy metal ions such as Cu2+, Co2+, Ni2+ and Zn2+ from aqueous media. Absorption studies revealed that the absorption of metal ions by the hydrogels followed the order Cu2+ > Ni2+ > Co2+ > Zn2+. For the mechanism of absorption, both Freundlich and Langmuir absorption isotherms were applied. Metal ion entrapped hydrogels were treated using an in situ chemical reduction method in order to convert the metal ions into metal nanoparticles for the synthesis of hybrid hydrogels. The synthesis and morphology were confirmed using FT-IR and SEM, while the absorbed metal amounts were measured using TGA and AAS. The hybrid hydrogels were further used as catalysts for the reduction of macro (methylene blue, methyl orange and congo red) and micro (4-nitrophenol and nitrobenzene) pollutants from the aqueous environment. The catalytic performance and re-usability of the hybrid hydrogels were successfully investigated.

Enhanced Water Barrier Properties of Surfactant-Free Polymer Films Obtained by MacroRAFT-Mediated Emulsion Polymerization

Abstract: The presence of low molar mass surfactants in latex films results in detrimental effects on their water permeability, gloss and adhesion. For applications as coatings, there is a need to develop formulations that do not contain surfactants and that have better water barrier properties. Having previously reported the synthesis of surfactant-free latex particles in water using low amounts (< 2 wt%) of controlled radical polymer chains (Lesage de la Haye et al. Macromolecules 2017, 50, 9315−9328), here we study the water barrier properties of films made from these particles and their application in anti-corrosion coatings. When films cast from aqueous dispersions of acrylate copolymer particles stabilized with poly(sodium 4-styrenesulfonate) (PSSNa) were immersed in water for three days, they sorbed only 4 wt.% water. This uptake is only slightly higher than the value predicted for the pure copolymer, indicating that the negative effects of any particle boundaries and hydrophilic stabilizing molecules are minimal. This sorption of liquid water is five times lower than what is found in films cast from particles stabilized with the same proportion of poly(methacrylic acid) (PMAA), which is more hydrophilic than PSSNa. In water vapor with 90% relative humidity, the PSSNa-based film had an equilibrium sorption of only 4 wt.%. A small increase in the PMAA content has a strong and negative impact on the barrier properties. Nuclear magnetic resonance relaxometry on polymer films after immersion in water shows that water clusters have the smallest size in the films containing PSSNa. Furthermore, these films retain their optical clarity during immersion in liquid water for up to 90 minutes, whereas all other compositions quickly develop opacity (“water whitening”) as a result of light scattering from sorbed water. This implies a remarkably complete coalescence and a very small density of defects, which yields properties matching those of some solvent borne films. The latex stabilized with PSSNa is implemented as the binder in a paint formulation for application as an anti-corrosive barrier coating on steel substrates and evaluated in accelerated weathering and corrosion tests. Our results demonstrate the potential of self-stabilized latex particles for the development of different applications, such as waterborne protective coatings and pressure-sensitive adhesives.

Optimization of the high-throughput synthesis of multiblock copolymer nanoparticles in aqueous media via polymerization-induced self-assembly

Abstract: Over the past fifteen years or so, polymerization-induced self-assembly (PISA) has become widely recognized as a powerful and versatile platform technology for the synthesis of a wide range of block copolymer nanoparticles of controlled size, shape and surface chemistry. In the present study, we report that PISA formulations are sufficiently robust to enable high-throughput experiments using a commercial synthesis robot (Chemspeed Autoplant A100). More specifically, we use reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerization of either n-butyl methacrylate and/or benzyl methacrylate to prepare various examples of methacrylic multiblock copolymer nanoparticles using a poly(methacrylic acid) stabilizer block. Adequate stirring is essential to generate sufficiently small monomer droplets for such heterogeneous polymerizations to proceed efficiently. Good reproducibility can be achieved under such conditions, with well-defined spherical morphologies being obtained at up to 45% w/w solids. GPC studies indicate high blocking efficiencies but relatively broad molecular weight distributions (Mw/Mn = 1.36–1.85), suggesting well-defined (albeit rather polydisperse) block copolymer chains. These preliminary studies provide a sound basis for high-throughput screening of RAFT-mediated PISA formulations, which is likely to be required for commercialization of this technology. Our results indicate that methacrylic PISA formulations enable the synthesis of diblock and triblock copolymer nanoparticles in high overall yield (94–99%) within 1–3 h at 70 °C. However, tetrablocks suffer from incomplete conversions (87–96% within 5 h) and hence most likely represent the upper limit for this approach.

Temperature and pH-Dual Responsive AIE-Active Core Crosslinked Polyethylene–Poly(methacrylic acid) Multimiktoarm Star Copolymers

Abstract: A series of aggregation-induced emission (AIE) active core crosslinked miktoarm star copolymers, having multi polyethylene (PE) and poly(methacrylic acid) (PMAA) arms, were synthesized and their thermal/pH responsive properties were studied. The procedure involves (a) the synthesis of PE-Br by polyhomologation of dimethylsulfoxonium methylide with triethylborane as initiator, followed by oxidation-hydrolysis/esterification reactions and of poly(tert-butyl methacrylate) (PtBMA-Br) by atom transfer radical polymerization (ATRP) of tert-butyl methacrylate, (b) the synthesis of (PE)n-(PtBMA)m-P(TPE-2St) by ATRP of a double styrene-functionalized tetraphenylethene (TPE-2St) with PE-Br and PtBMA-Br macroinitiators, and (c) the hydrolysis of (PE)n-(PtBMA)m-P(TPE-2St) to afford the amphiphilic miktoarm star copolymers (PE)n-(PMMA)m-P(TPE-2St). Due to their spherical core–shell structure (temperature-responsive) and the presence of hydrophilic PMAA (pH-responsive) and TPE-2St (AIE), these miktoarm star copolymers ...

Rational design of a molecularly imprinted polymer for dinotefuran: theoretical and experimental studies aimed at the development of an efficient adsorbent for microextraction by packed sorbent

Abstract: In this work, we studied theoretically the formation process of a molecularly imprinted polymer (MIP) for dinotefuran (DNF), testing distinct functional monomers (FM) in various solvents through density functional theory calculations. The results revealed that the best conditions for MIP synthesis were established with methacrylic acid (MAA) as FM in a 1 : 4 stoichiometry and with chloroform as the solvent. This protocol showed the most favourable stabilization energies for the pre-polymerization complexes. Furthermore, the formation of the FM/template complex is enthalpy driven and the occurrence of hydrogen bonds between the DNF and MAA plays a major role in the complex stability. To confirm the theoretical results, MIP was experimentally synthesized considering the best conditions found at the molecular level and characterized by scanning electron microscopy and thermogravimetric analysis. After that, the synthesized material was efficiently employed in microextraction by packed sorbent combined with high-performance liquid chromatography in a preliminary study of the recovery of DNF from water and artificial saliva samples.

Development of Acyclovir Loaded β-Cyclodextrin-g-Poly Methacrylic Acid Hydrogel Microparticles: An In Vitro Characterization

Abstract: In this work, successful efforts have been performed for solubility enhancement of acyclovir. pH-sensitive β-Cyclodextrin-g-poly methacrylic acid (MAA) hydrogel microparticles were developed. β-Cyclodextrin, MAA, N,N-methylene bisacrylamide were used as polymer, monomer, and cross-linker, respectively. Nine different formulations (BM-1 to BM-9) were prepared by aqueous free radical polymerization. Developed microparticles were characterized for FTIR, Differential Scanning Calorimetry/Thermo Gravimetric Analysis, PXRD, energy-dispersive x-ray spectroscopy, SEM, TEM, optical microscopy, zeta sizer, percent equilibrium swelling (%ES), solubility studies, and in vitro drug release studies. Higher swelling results (83.68%) were obtained at pH 7.4 in less than 3 h. Porous surfaces with drug were seen in TEM images. Maximum release was observed at pH 7.4 (89.51%). Solubility enhancement was 7.38-fold in water as compared to pure acyclovir. Thermal stability of grafted microparticles was increased up to 440.13°C. A potential approach for solubility enhancement was successfully developed.

Selective Separation of Methacrylic Acid and Acetic Acid from Aqueous Solution Using Carboxyl-Functionalized Ionic Liquids

Abstract: Five kinds of carboxyl-functionalized quaternary ammonium ionic liquids (ILs), tricaprylmethylammonium succinate ([A336]Suc), tricaprylmethylammonium aspartate ([A336]Asp), tricaprylmethylammonium glutamate ([A336]Glu), tricaprylmethylammonium trifluoroacetate ([A336]TFA), and tricaprylmethylammonium phthalate ([A336]Pha), with strong hydrophobicity and hydrogen bond basicity were used to separate methacrylic acid (MAA) and acetic acid (HAc) from an aqueous solution. [A336]Suc shows better extraction performance than the other ILs because of the stronger hydrogen bonding basicity. Even though HAc shows the antagonistic effect on the extraction of MAA, the selectivity of MAA to HAc is achieved 54.70 for [A336]Suc at the optimized extraction conditions. The molecular mechanism of the extraction by IL is revealed by combining FT-IR and quantum chemical calculations. The results indicate that multiple hydrogen bonds are presented in the IL–acid complex which plays an important role in the acid extraction. Mea...