Presence Of Methylenebisacrylamide Research Articles

Rheological properties of poly(ethylene glycol)/poly(N‐isopropylacrylamide‐co‐2‐acrylamido‐2‐methylpropanesulphonic acid) semi‐interpenetrating networks

AbstractFor the increasing demands of multifunctional materials in applications such as drug delivery system, a pH‐ and temperature‐responsive polyelectrolyte copolymer gel system was studied using rheometry. Rheological properties, determined by plate–plate rheometry in oscillatory shear, of hydrogels formed by free radical initiated copolymerization of N‐isopropylacrylamide (NIPA) and 2‐acrylamido‐2‐methylpropanesulphonic acid (AMPS) in the presence of methylene bisacrylamide (MBAA) as crosslinker are compared with the properties of semi‐interpenetrating network (SIPN) polyelectrolyte gels made by incorporation of poly(ethylene glycol) with molar mass 6000 g mol−1 (PEG6000). Based on our systematic studies for this PEG/SIPN system, the effects of initiator and crosslinker concentration, relative proportions of comonomer units in the main chains, PEG6000 content and temperature on viscoelastic properties, unusual high storage moduli at small strain for the SIPN were discussed. The SIPN gel with characteristics of PEG molecules as well as pH and temperature responsiveness from AMPS and NIPA units has potential application in drug delivery system design. Ice‐like rheological behavior of the PEG/AMPS‐NIPA SIPN gels at low temperature was first time reported and water remains homogeneous without phase separation in PEG/AMPS‐NIPA SIPN hydrogels at low temperature may be considered as an ideal candidate for water storage material. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Modified carrageenan. 6. crosslinked graft copolymer of methacrylic acid and kappa-carrageenan as a novel superabsorbent hydrogel with low salt- and high pH-sensitivity

A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan (κC), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for κC-g-polymethacrylic acid (κC-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were preliminarily investigated. Absorbency in aqueous salt solutions of lithium chloride, sodium chloride, potassium chloride, calcium chloride, and aluminum chloride indicated that the swelling capacity decreased with increased ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. The swelling of superabsorbing hydrogels was measured in solutions with pH ranging from 1 to 13. In addition, the pH reversibility and on-off switching behavior, at pH levels of 3.0 and 8.0, give the synthesized hydrogels great potential as an excellent candidate for the controlled delivery of bioactive agents.

Modified chitosan 4. Superabsorbent hydrogels from poly(acrylic acid-co-acrylamide) grafted chitosan with salt- and pH-responsiveness properties

Graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto chitosan was carried out by using potassium persulfate (KPS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. The effect of reaction variables, such as MBA concentration and AA/AAm ratio on the water absorbency capacity have been investigated. The polymer structures were confirmed by FTIR spectroscopy. Water absorbencies were compared for the hydrogels before and after alkaline hydrolysis. In the non-hydrolyzed hydrogel, enhanced water absorbency was obtained with increasing AA in monomer feed. However, after saponification, the sample with high AAm ratio exhibited more water absorbency. These behaviors were discussed according to structural parameters. The swelling kinetics of the superabsorbing hydrogels was studied as well. The hydrogels exhibited ampholytic and reversible pH-responsiveness characteristics. The swelling variations were explained according to swelling theory based on the hydrogel chemical structure. The hydrogels exhibited salt-sensitivity and cation exchange properties. The pH-reversibility and on–off switching properties of the hydrogels make the intelligent polymers as good candidates for considering as potential carriers for bioactive agents, e.g. drugs.

Preparation of partly hydrophobized, crosslinked polyacrylamide particles by terpolymerization of acrylamide/N,N-methylenebisacrylamide/styrene in inverse microemulsion

Free-radical polymerization of a termonomer system comprising acrylamide (AAm) N,N ′-methylenebisacrylamide (MBAAm) and styrene (S) initiated by water-soluble ammonium peroxodisulphate (APS) or by toluene-soluble dibenzoyl peroxide (DBP) in inverse microemulsion (toluene/S/AOT//water//AAm/MBAAm), leads to the formation of partly hydrophobized crosslinked polymer particles of tailored chemical composition, degree of crosslinking and polymer particle size. Styrene strongly decreases the rate of terpolymerization, while the presence of MBAAm has almost no effect on the polymerization rates observed. This conclusion is valid for both APS and DBP initiators. Increase of the S/T mass ratio (T is toluene) in inverse microemulsion leads to an increase of polymer particle diameter from about 20 nm to about 50 nm attributed to toluene swelling of the styrene-rich structural moieties of AAm-co-S copolymer located on the surface of polymer particles. Polymerization kinetics measurements pointed to the important role of exiting water soluble AAm and MBAAm monomer radicals generated by thermal decomposition of APS in water pools of inverse micelles for initiation of polymerization reactions of sparingly water-soluble S monomer in the oil-phase of the inverse microemulsion. It was shown that the polymerization and copolymerization reactions of S in the presence of AAm and/or MBAAm are effectively initiated by water-soluble APS and also by oil-soluble DBP initiators. During dialysis the polymerized single-phase water/oil Winsor IV inverse microemulsion gradually converts itself into a two-phase oil/water Winsor I dispersion system with volume fraction of aqueous phase Φaw ≈ 0.950. The water phase contains water swelled, crosslinked polymer particles of diameters 80–300 nm. During dialysis, toluene and the sodium salt of bis(2-ethyl hexyl)sulphosuccinic acid (AOT) partition between the oil phase of the dialysed dispersion system and the water dialysate. After evaporation of water from the dialysed inverse microemulsion, solid, dried, crosslinked polymer particles in the form of a transparent film, almost uncontaminated by AOT surfactant, were obtained. © 2000 Society of Chemical Industry

POLYMERIC SURFACTANTS BASED ON OLEIC ACID III. Copolymerization of Sodium Acrylamidostearate and Oleic Acid in a Lamellar Liquid Crystal

ABSTRACT Copolymerization of sodium acrylamidostearate (NaAAS) and oleic acid was performed in the lamellar liquid crystal (LLC) formed by NaAAS, oleic acid and water, in the absence of N.N’-methylenebisacrylamide (MBAA) and in the presence of MBAA, respectively. In the absence of MBAA, after the polymerization the lamellar structure remained, and the disorder of the lamellar liquid crystal was, to some extent, enhanced. Surface tension, small-angle X-ray diffraction, viscosity, and fluorescence methods were used to study the properties of the linear copolymer. The linear polymeric surfactant behaves like

Characteristics of polymeric peracids on acrylic acid-grafted polyethylene prepared by photografting in the presence of N, N′-methylenebisacrylamide

Photografting ( λ>300 nm, 60°C) of acrylic acid (AA) on low-density polyethylene (PE) film (thickness=30 μm), on which xanthone photoinitiator was coated earlier, was largely accelerated when small amounts of N, N′-methylenebisacrylamide (MBAAm) (0.67 and 3.3 mol% of AA monomer used) were added to the system. The addition of MBAAm did not affect distribution of the grafted chains in the cross section of the resultant AA-grafted PE film, which was measured by electron probe microanalysis. The AA-grafted samples were subjected to peroxidation with hydrogen peroxide in the presence of methanesulfonic acid at 25°C for 3 h to yield polymeric peracids. The amount of peracids formed was smaller for the grafted samples prepared in the system with MBAAm than those prepared in the system without MBAAm. Moreover, thermal decomposition of the polymeric peracids at 40°C was largely retarded for the former samples compared to the latter samples. These results suggest the formation of a cross-linked structure in the AA-grafted chains, which are introduced into PE substrate by photografting in the presence of MBAAm.

High-yield ?-ray-induced polymerization of bis-2-acetoacetoxyethyl methacrylate copper. II.

The copper (II) acrylic monomer Cu(aaem) 2 (aaem = 2-acetoacetoxyethyl methacrylate) undergoes high-yield y-ray copolymerization with dimethylacrylamide, styrene, and hydroxoethyl methacrylate in the presence of methylene bisacrylamide as crosslinking agent in dimethylformamide. The metalloorganic copolymers are fully characterized. Polymer-protected Cu(II) results in being extremely stable toward a number of reducing agents in different media.