SSWELLING AND PHYSICO-MECHANICAL PROPERTIES OF SYNTHESIZED SODIUM POLYACRYLATE HYDROGELS. (original) (raw)
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Poly(hydroxamic acid) hydrogels from poly(acrylamide): preparation and characterization
Polymer Bulletin, 2001
Poly(hydroxamic acid) (PHA) hydrogels from crosslinked poly(acrylamide) (PAAm) hydrogels containing different type crosslinkers such as such as N, N'methylene bisacrylamide (N) and ethyleneglycol dimethacrylate (E). The effect of crosslinkers on some physical properties was investigated. The structure of hydrogels was characterized spectroscopically and thermally. The swelling parameters of PHA in distilled water, such as percent equilibrium swelling (S eq %), initial swelling rate (r o), maximum equilibrium swelling (S max), diffusional exponent (n), network parameter (k) and diffusion coefficient (D) were calculated. It has been found that the ionogenity of PHA and the structure of the used crosslinkers during the synthesis have been effective on the swelling behaviour of the hydrogels.
Polymers for Advanced Technologies, 2022
Two kinds of hydrogels based on acrylic acid (AA) and acrylamide (AAm) without and with 2-acrylamido-2-methylpropane sulphonic acid (AMPS) were synthesized by radical polymerization using ethylene glycol dimethylacrylate as a crosslinker, to form double network (DN) and triple network (TN) interpenetrating polymer networks (IPN) gels, respectively. Fourier transform infrared spectroscopy (FTIR) presented evidence for the formation of polyacrylic acid (PAA)/polyacrylamide (PAAm) IPN gels and Michael-type grafting of poly(AAm-co-AMPS) onto PAA in TN gels. The scanning electron microscopy micrograph images exhibited a microporous morphology for synthesized IPN gels which was more compact in TN hydrogel samples compared with DN hydrogels due to the presence of AMPS (which is also proved through energy dispersive X-ray pattern and elemental analysis results) and higher crosslinking density in the structure of TN IPN hydrogels. Swelling behaviors indicated that TN superabsorbent gels presented 192.4 g/g water absorbency which was over three folds and 107 folds the swelling capacity of DN hydrogels and PAA in water, respectively. Additionally, TN alcogels showed enhanced swelling capacities of 99.1, 94.3, and 70.0 g/g in dimethyl sulfoxide, methanol and ethanol, respectively. The significant improvements in the values of absorbency related to TN gels compared to other samples can be attributed to the strong ionic sulfonic acid groups (SO 3 H) in AMPS along with hydrogen bonding as a strong polyelectrolyte and the formation of a threecomponent interpenetrating network structure with higher crosslink density. This structure formed in TN IPN gels can be responsible for elastic behavior, stable gel formation, and enhanced thermal stability of IPN hydrogels, as indicated by rheological, dynamic mechanical thermal analysis (DMTA), and thermogravimetric analysis (TGA) results. K E Y W O R D S acrylate-based hydrogels, double and triple network, interpenetrating polymer networks (IPNs) 1 | INTRODUCTION Polymeric gels, also called gelators or gelling agents, can swell in both aqueous and organic liquid and absorb these supported media several times their weight to form hydrogels and organic gels, respectively, due to their three-dimensional network structure. 1-5 Hydrogels are widely used in versatile applications, including scaffolds for regenerative medicine and tissue engineering due to their hydrated nature and
the influence of crosslinkers and the relative content of sodium acrylate on the swelling properties, the initial swelling rate and the swelling rate constant, swelling exponent, swelling coecients and diusional behaviour of water in the hydrogel systems were examined. Acrylamide-sodium acrylate hydrogels were swollen in the range 860-12870% in water, while acrylamide hydrogels swelled in the range 770-1420%. The equilibrium water content of acrylamide-sodium acrylate hydrogel systems was calculated in the range 0.8851-0.9922. The water intake of hydrogels followed a non-Fickian type diusion.
International Journal of Plastics Technology, 2009
Poly (acrylamide-co-acrylic acid) [poly (AAm-co-AAc)]-based hydrogels were prepared by varying the cross-linking agent concentration (NMBA) in the range of 0.0077% to 0.077%. The effect of the NMBA content on swelling parameters, such as water absorbency, swelling ratio on the hydrogel was studied by keeping two monomers content, that is, AAm and AAc constant. The effect of KPS as an initiator in the range of 0.1% to 0.5% on the water absorbency of the hydrogels was also studied. The swelling value could be modulated in a great range by varying the cross-linking agent (NMBA) or initiator (KPS) concentration at fi xed monomer concentration. The synthesized hydrogels were characterized by FTIR, SEM and network parameters, such as average molecular weight between cross-links (Mc), cross-link density (q) and mesh size (ξ). The experimental results showed that the equilibrium water absorbency decreases from 707.23 to 389 with increasing the NMBA content from 0.0096 % to 0.0385%. The network parameters, such as average molecular weight between cross-links (Mc) were decreased from 2.33 x 10 12 to 2.30 x 10 11 and cross-link density (q) decreased from 3.07 x 10-11 to3.09 x 10-11 ; although mesh size (ξ) increased from 3.00 x 10 6 to 8.89 x 10 6 with increase in percentage of NMBA content from 0.009265% to 0.077%. The equilibrium water absorbency of various hydrogels were studied in distilled water and different types of saline solutions, which exhibited that hydrogels have higher equilibrium water absorbency in 0.009% saline (NaCl) solution than in 0.09% and 0.9% saline solutions. From the results it was clear that water absorbency increased from 302 to 573 g water/g sample with increasing the KPS content from 0.1 to 0.5%.
Arabian Journal of Chemistry, 2017
Poly(acrylamide-co-acrylic acid) poly(AAm-co-AAc) hydrogels were prepared by free radical polymerization initiated by redox initiators of ammonium peroxodisulphate (APS) and N,N,N 0 ,N 0-tetramethyl ethylene diamine (TEMED); N,N 0-methylene bisacrylamide (BIS) was employed as a crosslinking agent. The copolymers were characterized by infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dynamic rheology and swelling measurements. Results indicated that the strong interaction in the hydrogels resulted in the formation of a more stable copolymer. The single glass transition temperature (T g) in sample suggested that the two polymers into the hydrogel have a good miscibility. The elastic modulus (G 0) and linear viscoelastic region increased with increase in PAAc concentration. The oscillation time sweep study of the hydrogels exhibited a flat G 0 indicating a stable structure and good mechanical strength. In the swelling measurements, the gels exhibited appreciable water uptake and were highly sensitive to pH environment. So the poly(AAm-co-AAc) hydrogel will have promising application in pharmaceutical use and in biomaterials.
Macromolecular Symposia, 2012
Stimuli-responsive polyampholyte hydrogels were synthesized by the copolymerization of acrylic acid (AAc) and acrylamide (AAm) by thermal methods. Polyampholytic hydrogels are crosslinked networks composed of positively and negatively charged repeating units that show entirely different properties from their origins. In this work, polyampholytic poly (acrylic acid acrylamide) hydrogels prepared in different molar ratio in feed composition by thermal methods. The structures of hydrogels were characterized by FTIR analysis. Thermal stabilities of the hydrogels were investigated using TGA analysis. The swelling behavior of hydrogels investigated by some parameters such as pH, salt concentration and temperature. We determined this swelling capacity in different temperatures (25, 50 and 70 8C) and different pH (2, 7 and 12). In addition, we investigated the effects of different salts such as LiCl, CaCl 2 , Na 2 SO 4 and NaCl with concentration of 0.1, 0.2 and 0.3 M on swelling properties.
Journal of Applied Polymer Science, 2006
The mechanical and thermodynamic properties of poly(acrylic acid-co-methyl methacrylate) hydrogels with varying crosslinker N,N 0 -methylenebisacrylamide (NMBA) content are reported. A higher NMBA content generally led to a stronger and harder gel with lower water content. Swelling capacity decreased as the NMBA concentration increased between 0.5% and 2%, remaining constant beyond this range. The temperature changes of the partial molar Gibbs free energy of dilution and enthalpic and entropic contributions were examined. The thermodynamic parameters showed that swelling was an unfavorable and endothermic process. The freezing and nonfreezing water in the hydrogel was determined by differential scanning calorimetry (DSC). Freezing water content decreased with increasing crosslinker (NMBA) content, whereas the ratio of nonfreezing water to total water content increased with NMBA content because of the promoting of hydrophobic interactions in the hydrogels.
2013
Interpenetrating polymeric network (IPN) hydrogels of acrylamide (AAm) with , -bisstyryl (2,4ionene) were synthesized by free-radical copolymerization in water with N,N-methylenebisacrylamide (BAAm) as the crosslinker, ammonium persulphate (APS) as the initiator and N,N,N’,N”-tetramethylethylenediamine (TEMED) as the activator. The water uptake and the sorption properties of the IPN hydrogels were investigated as a function of composition and measured as gram of water per minute. The swelling behavior of the gels was specified by a relatively fast rate of swelling at the beginning of the process. The gel fraction and degree of swelling at different pH, temperature and salt concentration were studied. It was found that the gel fraction increased with BAAm content and AAm ratio in the copolymer but never reached to 100%. Thermogravimetric analysis (TGA) and mechanical properties such as DMTA and tensile strength were performed. The results of DMTA and TGA showed that T and T of the IP...