Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle ti...Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.展开更多
N-isopropylacrylamide (NIPAAm) was used to synthesize NIPAAm homopolymer (nonionized) and NIPAAm-sodium methacrylate copolymer (ionized). The swelling equilibria for both gels were obtained in aqueous solution of etha...N-isopropylacrylamide (NIPAAm) was used to synthesize NIPAAm homopolymer (nonionized) and NIPAAm-sodium methacrylate copolymer (ionized). The swelling equilibria for both gels were obtained in aqueous solution of ethanol with concentration ranging from 0 to 100%(by mass) at 25℃. The swollen gel in water shrank first with the addition of a small amount of ethanol and then reswelled with further addition of ethanol showing not only a discontinuous volume phase transition but also a typical reentrant phenomenon. A thermodynamic model based on the UNIQUAC with the 'free-volume' contribution was applied to correlate and predict the swelling behavior of the poly(NIPAAM)-gels in ethanol-water mixture.展开更多
Poly (methacrylic acid-co-poloxamer) hydrogel networks were synthesized byfree-radical solution polymerization, and the dynamic swelling and in vitro release properties ofmodel drugs, dextromethorphan hydrobromide (DM...Poly (methacrylic acid-co-poloxamer) hydrogel networks were synthesized byfree-radical solution polymerization, and the dynamic swelling and in vitro release properties ofmodel drugs, dextromethorphan hydrobromide (DMP) and vitamin B_(12) (VB_(12)) were studied. Thesegels exhibited pH-dependant swelling and sustained drug release properties, and the water uptakerate and drug release rate in neutral or basic media were higher than that in acidic media. Theresults showed that the water uptake followed non-Fickian or zero order process in neutral or basicmedia, and the release of model drugs from hydrogels of appropriate composition was of zero orderkinetics over a period of several hours.展开更多
文摘Polyvinyl alcohol(PVA) physiological saline gel was prepared using physiological saline solution of the polymer by freezing and thawing method. The influences of the concentration of PVA, freezing and thawing cycle times and solvent swelling media on the swelling properties of PVA saline gel were investigated. The result show that the electrolytical ions have great effect on the swelling behavior of PVA saline gel. The equilibrium swelling ratio of PVA saline gel in aqueous swelling media is larger than that in saline swelling media. Also, the equilibrium swelling ratios of PVA saline gel in aqueous and in saline media decrease with the increase of gel concentration and the increase of freezing and thawing cycle times. The decreasing speed of equilibrium swelling ratio with the increase of freezing and thawing cycle times of PVA gel in distilled water is faster than that in physiological saline. The swelling kinetic equation can sufficiently describe the swelling behavior of PVA physiological saline gel.
基金Supported by the Science and Tchnology Ministry of Fujian(No.2001Z046)and the Education Commission of Fujian(No.K2001004).
文摘N-isopropylacrylamide (NIPAAm) was used to synthesize NIPAAm homopolymer (nonionized) and NIPAAm-sodium methacrylate copolymer (ionized). The swelling equilibria for both gels were obtained in aqueous solution of ethanol with concentration ranging from 0 to 100%(by mass) at 25℃. The swollen gel in water shrank first with the addition of a small amount of ethanol and then reswelled with further addition of ethanol showing not only a discontinuous volume phase transition but also a typical reentrant phenomenon. A thermodynamic model based on the UNIQUAC with the 'free-volume' contribution was applied to correlate and predict the swelling behavior of the poly(NIPAAM)-gels in ethanol-water mixture.
文摘Poly (methacrylic acid-co-poloxamer) hydrogel networks were synthesized byfree-radical solution polymerization, and the dynamic swelling and in vitro release properties ofmodel drugs, dextromethorphan hydrobromide (DMP) and vitamin B_(12) (VB_(12)) were studied. Thesegels exhibited pH-dependant swelling and sustained drug release properties, and the water uptakerate and drug release rate in neutral or basic media were higher than that in acidic media. Theresults showed that the water uptake followed non-Fickian or zero order process in neutral or basicmedia, and the release of model drugs from hydrogels of appropriate composition was of zero orderkinetics over a period of several hours.
