Acrylonitrile-methacrylic Acid Research Articles

Characterization and in vitro drug release properties of core–shell hydrogel prepared by gamma irradiation

ABSTRACTA hydrogel system was prepared based on core–shell approach for the delivery of trifluoperazine. Acrylonitrile (AN) core and methacrylic acid (MAA) shell copolymer were performed using gamma irradiation. The resulted system has been characterized by FTIR, TGA, TEM, and SEM techniques. The in vitro release study showed that the maximum drug released was 6.11 mg g−1 for AN–MAA copolymer through 120 min and 22.34 mg g−1 for AN-core–MAAc shell through 240 min. The results demonstrated that AN-core–MAAc had better properties than AN–MAA copolymer which means the preparation technique highly affects the properties of the system.

Effect of comonomer on the viscoelastic behavior of co-poly (acrylonitrile) solutions

Three copolymers of acrylonitrile-methacrylic acid [P(AN-co-MAA)], acrylonitrile-ammonium salt of methacrylic acid [P(AN-co-AMA)], acrylonitrile-methacrylamide-itaconic acid [P(AN-MAM-IA)] and PAN homopolymer were synthesized by aqueous dispersion polymerization technique. The polymerization conditions were adjusted in such a way to produce polymers with similar composition and molecular weight. The influence of comonomer nature on the viscoelastic behavior and spinnability of copolymer/dimethylsulfoxide (DMSO) solutions were investigated. It was found that incorporation of these comonomers into PAN chains led to intense decrease in zero-shear viscosity to lower value as well as appearance of distinct plateau in comparison with PAN homopolymer. However, comparing the results of complex viscosity and shear viscosity of each PAN polymer showed different shear-thinning behavior, typical deviation from Cox-Merz rule at high deformation rates. Amongst these copolymer solutions, P(AN-co-AMA) exhibited the longest relaxation time (λ) at low and medium frequencies. The lower values of frequency dependence of G′ (n′) and cross over frequency (ωc) of storage modulus (G′) and loss modulus (G″) indicated that P(AN-co-AMA) was more elastic than other PAN copolymer solutions. The log-log plots of tan δ versus ω demonstrated that the comonomer nature affects the sol-gel transition behavior and elastic character of copolymer solutions. On average, based upon the slope of logGʹ versus logGʺ data, the incorporation of comonomers inside PAN chains led to ~50 % increase in the homogeneity of solutions compared to PAN homopolymer.

Preparation and properties of foamed materials based on acrylonitrile-methacrylic acid copolymers

The physicomechanical properties of foamed polymethacrylimides formed by heat treatment of acrylonitrile-methacrylic acid copolymers were studied in relation to the kind of the foaming agent and to the concentrations of the foaming agent and acrylamide.

Preparation of foamed polymethacrylimide structural materials from cross-linked copolymers of acrylonitrile and methacyrlic acid

A study of the influence exerted by the structure and concentration of cross-linking monomers on the structure and physicomechanical properties of polymethacrylimide foamed plastics formed by heat treatment of acrylonitrile-methacrylic acid copolymers showed that the use of allyl methacrylate, ethylene glycol dimethacrylate, or triallyl isocyanurate as cross-linking monomers allows preparation of foamed materials with the density in the range 90–180 kg m−3 and with enhanced strength. A study by differential scanning calorimetry showed that the foamed plastics based on the cross-linked copolymers remain stable on heating to 200–210°C. This fact allows these materials to be used as thermal adhesives in multilayered items.

Mathematical Modeling of Hyperbranched Water‐soluble Polymers with Applications in Drug Delivery

AbstractAlthough the method of moments has been used to determine the properties of copolymerizations, accounting for branching has either been ignored or required multiple dimensions to simulate. In this work, we extend our previous modeling efforts to account for hyperbranching, a form of polymerization that is particularly useful in the synthesis of targeted delivery vehicles capable of encapsulating drugs for localized therapeutics, without invoking higher dimension moment treatments. Specifically, the case of RAFT polymerization with a polymerizable double bond incorporated into the RAFT agent is modeled. This gives a very highly‐branched material without the complexity of dendrimer synthesis. The model is then used to simulate three copolymerizations that illustrate the power of this model to accurately predict the copolymer properties and illustrate the polydispersity of the individual segments of the hyperbranched polymer, and the overall hyperbranched polymer. This paper models three different hyperbranched copolymer blends: acrylamide–acrylic acid, acrylonitrile–methacrylic acid, and ethylene–styrene. The first case is of specific interest in the development of hyperbranched polymers for drug delivery. The other two are included in order to explore the effects of specific kinetics on branching. magnified image

Cloth filter for recovery of uranium from radioactive waste

A cloth filter incorporated with amidoxime/carboxyl groups was synthesized for recovery of uranium from radioactive waste obtained from nuclear fuel fabrication laboratories. The cloth filter was synthesized by radiation-induced grafting of acrylonitrile/methacrylic acid (AN/MA) onto a cotton cloth and followed by amidoximation reaction at a weight ratio of AN to MA of 80/20. The effect of comonomer composition on the grafting ratio and AN composition in the graft chain was studied. The reactivity of AN for grafting into the cotton cloth was found to be less than that of the MA acid. The incorporation of the functional groups was confirmed by FT–IR spectra. The cloth filter possessed good mechanical properties and thermal and chemical stability suitable for practical use. The uranium uptake ratio reached 95% at 298K and pH 9–9.5.

Development of acrylonitrile copolymers for scale control in cooling water systems

The formation of calcium sulphate and carbonate scale has been prevented by using acrylonitrile-acrylic acid (AN-AA) and acrylonitrile-methacrylic acid (AN-MAA) copolymers over a temperature range of 50–80°C at different pHs from 7.0 to 8.5. The efficiency of the antiscalants was assessed by various techniques such as a chemical screening test, constant potential electrolysis and impedance measurements. The change in crystal habits by the addition of antiscalant was seen using XRD spectrum and SEM photographs. The effectiveness of polymers on microorganisms and forming gelation with calcium ion and iron-dispersing ability were also studied. The amount of scale deposition increased with increase in temperature and pH. The polymers acted as good antiscalants at low temperature and pH ranges. They also acted as good flocculants under some special conditions. For example, at a higher pH of 8.5 and temperature 80°C with 20 ppm dosage level of the AN-AA polymer, 100% was achieved. Further, they had good iron dispersibility and can gelate with Ca 2+ ions.

Effect of reaction medium on radical copolymerization of acrylonitrile with vinyl acids

Radical polymerization of acrylonitrile (AN) with methacrylic acid (MAA) and itaconic acid (IA) was carried out in a mixture of dimethylformamide (DMF) and water at 70°C using α, α′-azobisisobutyronitrile (AIBN) as an initiator. Monomer feed in the polymerization vessel was 98:2 (AN:MAA/IA) in the molar ratio, and the DMF:H2O ratio was varied between 20:80 and 80:20 (w/w). Copolymers were characterized by FTIR, carbon, hydrogen, nitrogen elemental CHN analysis, 1H- and 13C-NMR, and viscometry. The rate of polymerization (Rp) was found to decrease with an increase in DMF concentration in the reaction medium, that is, in 20% DMF for AN–MAA system, the Rp is 1.23% min−1 in 1 h of polymerization, while in 80% DMF, Rp is reduced to 0.37% min−1. The nature of the vinyl acid also affects the Rp. It has been shown that the rate of polymerization is higher for an AN–MAA system as compared to an AN–IA system (Rp = 1.0% min−1) and the methacrylic or itaconic acid content in the copolymer increases with an increase in the DMF concentration. The MAA content in the poly(AN–MAA) polymer produced in 20% DMF is 3.2 mol %, which increases to 6.1 mol % (calculated through FTIR spectra) when DMF is increased to 80% in the reaction medium. The intrinsic viscosity [η] of the poly(AN–IA) and poly(AN–MAA) copolymers in DMF was found to be in the range of 0.67–2.90 dLg−1 depending on the reaction medium. In determining the intrinsic viscosity, a definite deviation from rectilinearity of the concentration dependence in the high-dilution region is observed, thereby demonstrating the polyelectrolyte behavior of these polymers. Through FTIR and NMR spectral studies, PAN homopolymer and other copolymers have shown the formation of a small quantity of acrylamide units. In addition copolymer P10, which contains 10.1 mol % IA, has shown anhydride formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1640–1652, 2001

Mechanism and Kinetics of Stabilization Reactions of Polyacrylonitrile and Related Copolymers IV. Effects of Atmosphere on Isothermal DSC Thermograms and FT-IR Spectral Changes during Stabilization Reaction of Acrylonitrile/Methacrylic Acid Copolymer

Structure formation during the stabilization reactions of the acrylonitrile/methacrylic acid (AN/MAA) copolymer under air, O2 and N2 was studied by an organized combination of isothermal DSC thermograms and FT-IR spectra. Under the oxidative atmosphere evolved heat was very large and the conjugated cyclic structure was formed as a stable structure. Particularly in pure O2 gas the stabilization reaction attained to the most advanced state. Under N2 the evolved heat was smallest and the resulted structure was thought to be a non-conjugated cyclic imine-enamine tautomerism structure.

Mechanism and Kinetics of Stabilization Reactions of Polyacrylonitrile and Related Copolymers III. Comparison among the Various Types of Copolymers as Viewed from Isothermal DSC Thermograms and FT-IR Spectral Changes

Relationship between thermal behavior and structural change was studied by an organized combination of isothermal DSC thermograms and FT-IR spectra so as to investigate the stabilization reactions of acrylonitrile/acrylamide (AN/AAM) copolymer in comparison with those of acrylonitrile/methacrylic acid (AN/MAA) copolymer and polyacrylonitrile (PAN). The isothermal DSC exothermic thermogram of the AN/AAM copolymer was broader than that of the AN/MAA copolymer and a little sharper than that of PAN, indicating that structural changes during stabilization proceed in the AN/AAM sample more slowly than that in the AN/MAA copolymer and more rapidly than PAN homopolymer.

Mechanism and Kinetics of Stabilization Reaction of Polyacrylonitrile and Related Copolymers II. Relationships between Isothermal DSC Thermograms and FT-IR Spectral Changes of Polyacrylonitrile in Comparison with the Case of Acrylonitrile/Methacrylic Acid Copolymer

The relationship between thermal behavior and structural change has been studied by an organized combination of isothermal DSC thermograms and FT-IR spectra measured for the stabilization reaction of polyacrylonitrile (PAN) in comparison with the case of acrylonitrile/methacrylic acid (AN/MAA) copolymer. The isothermal DSC exothermic thermogram of PAN is much broader and the structural changes proceed much more slowly than the case of AN/MAA copolymer. On the stabilization of PAN, at first, some nitrile groups change into amide groups, which initiate the dehydrogenation and cyclization reactions. This dehydrogenation reaction proceeds rather faster than the cyclization. The comonomer MAA was considered to accelerate the dehydrogenation reaction more effectively than the cyclization reaction.

Solution polymerization of acrylonitrile with vinyl acids in dimethylformamide

Solution copolymerization of acrylonitrile (AN) with various vinyl acids, i.e., acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA), was carried out in DMF at 70°C using α,α′-azobisisobutyronitrile (AIBN) as an initiator with an acidic monomer of 0.012–0.092 mol %. Copolymers were characterized by FTIR, CHN analysis, 1H-and 13C-NMR, and viscometry. The reactivity ratios were calculated using Fineman–Ross and Kelen–Tüdos methods. In all three systems, the value of r1 (AN) is much less than the value of r2. However, the r2 (MAA) is higher than r2 of (AA) and (IA). The reactivity ratios were calculated using Q and e schemes also. The results are in good agreement with experimentally calcualted data. The tacticity and sequence length distribution of these copolymers were calculated using 13C-NMR from CN and CH signals. It was observed that the isotacticity of acrylonitrile–itaconic acid copolymer P(AN–IA) with 8.2 mol % of a comonomer is lower than that of P(AN–MAA) with 10.3 mol % and P(AN–AA) with 7.61 mol %. © 1996 John Wiley & Sons, Inc.

Solution polymerization of acrylonitrile with vinyl acids in dimethylformamide

Solution copolymerization of acrylonitrile (AN) with various vinyl acids, i.e., acrylic acid (AA), methacrylic acid (MAA), and itaconic acid (IA), was carried out in DMF at 70°C using α,α′-azobisisobutyronitrile (AIBN) as an initiator with an acidic monomer of 0.012–0.092 mol %. Copolymers were characterized by FTIR, CHN analysis, 1H-and 13C-NMR, and viscometry. The reactivity ratios were calculated using Fineman–Ross and Kelen–Tudos methods. In all three systems, the value of r1 (AN) is much less than the value of r2. However, the r2 (MAA) is higher than r2 of (AA) and (IA). The reactivity ratios were calculated using Q and e schemes also. The results are in good agreement with experimentally calcualted data. The tacticity and sequence length distribution of these copolymers were calculated using 13C-NMR from CN and CH signals. It was observed that the isotacticity of acrylonitrile–itaconic acid copolymer P(AN–IA) with 8.2 mol % of a comonomer is lower than that of P(AN–MAA) with 10.3 mol % and P(AN–AA) with 7.61 mol %. © 1996 John Wiley & Sons, Inc.

Pyrolysis of acrylonitrile-methacrylic acid copolymers and derivatives

Pyrolyses of acrylonitrile-methacrylic acid copolymers and their sodium salts were studied under inert atmosphere at various heating rates using thermogravimetric analysis coupled with gas liquid chromatography, thermal volatilization analysis, differential scanning calorimetry and flash pyrolysis coupled with GLC and eventually mass spectrometric analysis. The mechanisms of the nitrile oligomerization and subsequent chain scission, giving rise to volatilization, are discussed in connection with the sequence distribution of monomeric units in the copolymers.

Orientation of smoke production in polyacrylonitrile

The introduction of ionic additives, such as KCN, or acidic comonomer units, such as methacrylic acid, which change the nature of the mechanism of nitrile oligomerization reaction from radical to ionic and cause its initiation at lower temperature, allows the level of obscurity and the total amount of smoke production, both in smouldering and flaming conditions to be decreased. An opposite result is obtained if diphenylpicrylhydrayl (DPPH) radicals in polyacrylonitrile is introduced; DPPH retards the initiation of the radical nitrile oligomerization reaction. The acrylonitrile-methacrylic acid copolymers have a limiting oxygen index, which increases with the methacrylic acid content. Owing to the increased amount of NH 3 produced during pyrolysis, the copolymers have a swelling behavior during the combustion test.