In vitro release of salicylic acid through poly(vinyl alcohol‐g‐itaconic acid) membranes

In this study, itaconic acid (IA) was grafted on poly(vinyl alcohol) (PVA) at two different grafting percentages, 7.0% (w/w) and 14.0% (w/w), and membranes were prepared from the grafted copolymer (PVA‐g‐IA). Performances of PVA and PVA‐g‐IA membranes for the transdermal release of salicylic acid (SA) at in vitro conditions were investigated by using 2.0 mg/mL SA solutions. Effect of the pH on the release of SA was studied by keeping pH of donor and acceptor solutions in a range of (2.1–7.4). Permeation studies were also carried on at different SA concentrations. Effect of temperature on the release of SA was investigated in the temperature range of (32–39) (±1)°C. Results showed that presence of IA decreased the release of SA from the PVA membranes and 73% SA was released at the end of 48 h at (32 ± 1)°C from the IA‐1 membranes. pH affected the release of SA through the grafted membranes and studies showed that release of SA was high with donor solution pH of 2.1. When the pH of donor and receiver solutions were kept at the same pH value, the overall SA% in permeate increased. Increase in concentration of SA decreased the release of SA for the studied membranes. Release of SA from PVA‐g‐IA membranes was temperature sensitive and increase in temperature from (32 ± 1)°C to (39 ± 1)°C increased the release percentage of SA by 24% (w/w). The overall activation energy for the permeation of SA through IA‐1 membrane was found to be 22.97 kJ/mol. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Drug‐release behavior of chitosan‐g‐poly(vinyl alcohol) copolymer matrix

Chitosan‐g‐poly(vinyl alcohol) (PVA) copolymers with different grafting percent were prepared by grafting water‐soluble PVA onto chitosan. The drug‐release behavior was studied using the chitosan‐g‐PVA copolymer matrix containing prednisolone in a drug‐delivery system under various conditions. The relationship between the amount of the released drug and the square root of time was linear. From this result, the drug‐release behavior through the chitosan‐g‐PVA copolymer matrix is shown to be consistent with Higuchi's diffusion model. The drug‐release apparent constant (K_H) was slightly decreased at pH 1.2, but increased at pH 7.4 and 10 according to the increasing PVA grafting percent. Also, K_H was decreased by heat treatment and crosslinking. The drug release behavior of the chitosan‐g‐PVA copolymer matrix was able to be controlled by the PVA grafting percent, heat treatment, or crosslinking and was also less affected by the pH values than was the chitosan matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 458–464, 1999     

Release of salicylic acid through poly(vinyl alcohol)/poly(vinyl pyrrolidone) and poly(vinyl alcohol‐g‐N‐vinyl‐2‐pyrrolidone) membranes

A controlled release profile of salicylic acid (SA) for transdermal administration has been developed. Poly (vinyl alcohol) (PVA) and Poly(vinyl alcohol)/Poly(vinyl pyrrolidone) (PVP) blended preparations were used to prepare the membranes by solvent‐casting technique. The release of the drug from the membranes was evaluated at in vitro conditions. The effects of PVA/PVP (v/v) ratio, pH, SA concentration and temperature were investigated. 60/40 (v/v) PVA/PVP ratio was found to be the best ratio for the SA release. Increase in pH and temperature was observed to increase the transport of SA. Instead of blending PVA with PVP, N‐Vinyl‐2‐pyrrolidone (VP) was grafted onto the PVA and the delivery performance for SA was compared with that of the blended PVA/PVP membranes. Grafted membranes gave higher transport percentages than the blended membranes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1244–1253, 2006     

Poly(acrylic acid‐co‐acrylamide‐co‐2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted nanocellulose/poly(vinyl alcohol) composite for the in vitro gastrointestinal release of amoxicillin

Superabsorbent polymer composites (SAPCs) are very promising and versatile materials for biomedical applications. This study concentrates on the development of novel cellulose‐based SAPC, Poly(acrylic acid‐co‐acrylamide‐co?2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted nanocellulose/poly(vinyl alcohol) composite, P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA, as a potential drug delivery vehicle. Amoxicillin was selected as a model drug, which is used for the treatment of Helicobacter pylori induced peptic and duodenal ulcers. P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA was synthesized by graft copolymerization reaction, and FTIR, XRD, SEM, and DLS analyses were performed for its characterization. Equilibrium swelling studies were conducted to evaluate the stimuli‐response behavior of the SAPC and found that equilibrium swelling was dependent on pH, contact time, temperature, ionic strength, concentration of crosslinker and PVA. Maximum drug encapsulation efficiency was found out by using different concentrations of amoxicillin. Drug release studies were carried out at simulated gastric and intestinal fluids and the release % was observed as maximum in intestinal fluids within 4 h. The drug release kinetics was investigated using Peppas' potential equation and follows non‐Fickian mechanism at pH 7.4. Thus, the drug release experiments indicate that P(AA‐co‐AAm‐co‐AMPS)‐g‐NC/PVA would be a fascinating vehicle for the in vitro administration of amoxicillin into the gastrointestinal tract. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40699.     

Characteristics of the nanofiltration composite membranes based on PVA and sodium alginate

Chemically stable nanofiltration (NF) composite membranes based on poly(vinyl alcohol) (PVA) and sodium alginate (SA) (hereafter, these membranes are called PVA/SA composite membranes) were prepared by coating microporous polysulfone (PSF) supports with dilute PVA/SA blend solutions. The PSF supports were pretreated with small monomeric compounds to reduce their pore size and to improve their hydrophilicity before coating with the PVA/SA blend solutions. The concentration of the PVA/SA blend solutions ranged from 0.1 to 0.3 wt %. The membranes prepared in this study were characterized with various methods such as SEM, FTIR, permeation tests, and z‐potential measurements. Especially, chemical stabilities of the membranes were tested, using three aqueous solutions with different pHs such as a HCl solution (pH 1), a K₂CO₃ solution (pH 12.5), and a NaOH solution (pH 13). Their chemical stabilities were compared with that of a polyamide (PA) composite membrane prepared from piperazine (PIP) and trimesoyl chloride (TMC). In this study, it was found that the PVA/SA composite membranes prepared showed not only good chemical stabilities but also good permeation performances in the range from pH 1 to 13. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2471–2479, 2001     

Pervaporation separation of water/dimethylformamide mixtures using poly(vinyl alcohol)‐g‐polyacrylamide copolymeric membranes

Grafted copolymeric membranes of poly(vinyl alcohol) with acrylamide (PVA‐g‐AAm) were developed and used in the pervaporation separation of water–dimethylformamide mixtures by varying the amount of water in the feed from 0 to 100%. From these data, the permeation flux, pervaporation separation index, diffusion coefficient, swelling index, and separation selectivity were calculated at 25, 35, and 45°C. The Arrhenius activation parameters for permeation flux ranged between 22 and 63 kJ/mol, while the activation energy for diffusion ranged between 23 and 67 kJ/mol. Separation selectivity was between 15 and 22. The highest permeation flux of 0.459 kg m^?2 h^?1 was obtained for the 93% grafted membrane at 90% of water in the feed mixture. The results are discussed using the principles of the solution–diffusion model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 273–282, 2002     

Polyacrylonitrile‐g‐poly(vinyl alcohol) membranes for the pervaporation separation of dimethyl formamide and water mixtures

Poly(vinyl alcohol) as well as its grafted copolymer membranes with polyacrylonitrile (PAN‐g‐PVA) were prepared and used to separate water and dimethyl formamide mixtures by the pervaporation technique. The three following membranes were prepared: (1) pure PVA; (2) 46% grafted PAN‐g‐PVA; and (3) 93% grafted PAN‐g‐PVA. Pervaporation separation experiments were carried out at 25°C for the feed mixture containing 10 to 90% water. By use of the transport data, permeation flux, separation selectivity, swelling index, and diffusion coefficients have been calculated. By increasing the grafting of the membrane, flux decreased, whereas separation selectivity increased slightly over that of pure PVA membrane. Arrhenius activation parameters for transport processes were calculated for 10 mass % water containing feed mixture by using flux and diffusion data obtained at 25, 35, and 45°C. Transport parameters were discussed in terms of sorption‐diffusion principles. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4091–4097, 2004     

Thermoresponsive and biocompatible poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) copolymer: Microwave‐assisted synthesis,characterization, and swelling behavior

Novel thermoresponsive poly(vinyl alcohol)‐graft‐poly(N,N‐diethylacrylamide) (PVA‐g‐PDEAAm) copolymers were prepared by microwave‐assisted graft copolymerization using a potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine (KPS/TEMED) initiator system. The structures of PVA‐g‐PDEAAm copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry/thermogravimetric analysis, gel permeation chromatography, X‐ray diffraction, and scanning electron microscopy. The effects of various process parameters on grafting were systematically studied: microwave power, KPS, monomer and PVA concentrations, and ultraviolet irradiation. Under optimal conditions, the maximum grafting percent and graft efficiency were 101% and 93%, respectively. Furthermore, a lower critical temperature of copolymers was measured in the range 29–31 °C by ultraviolet spectroscopy. The swelling behavior of graft membranes was carried out at various temperatures, and the results showed that the swelling behavior of membranes was dependent on the temperature. In vitro cell culture studies using L929 fibroblast cells confirmed cell compatibility with the PVA‐g‐PDEAAm copolymer and its membrane, making them an attractive candidate for drug delivery systems. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45969.     

pH‐ and temperature‐sensitive microfiltration membranes from blends of poly(vinylidene fluoride)‐graft‐poly(4‐vinylpyridine) and poly(N‐isopropylacrylamide)

The copolymer poly(vinylidene fluoride)‐graft‐poly(4‐vinylpyridine) (PVDF‐g‐P4VP) was prepared through the graft copolymerization of poly(vinylidene fluoride) with 4‐vinylpyridine. Through the blending of the PVDF‐g‐P4VP copolymer with poly(N‐isopropylacrylamide) (PNIPAm) in an N‐methyl‐2‐pyrrolidone solution, PVDF‐g‐P4VP/PNIPAm membranes were fabricated by phase inversion in aqueous media. Elemental analyses indicated that the blend concentration of PNIPAm in the blend membranes increased with an increase in the blend ratio used in the casting solution. Scanning electron microscopy revealed that the membrane surface tended to corrugate at a low PNIPAm concentration and transformed into a smooth morphology at a high PNIPAm concentration. The surface morphology and pore size distribution of the microfiltration membranes could be regulated by the blend concentration of the casting solution, temperature, pH, and ionic strength of the coagulation bath. X‐ray photoelectron spectroscopy revealed a significant enrichment of PNIPAm on the membrane surface. The flux of aqueous solutions through the blend membranes exhibited a pH‐ and temperature‐dependent behavior. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4089–4097, 2006     

Preparation and characterization of dual responsive sodium alginate‐g‐poly(vinyl alcohol) hydrogel

Poly(vinyl alcohol) (PVA) was chosen as a controllable gelator to prepare sodium alginate (SA)‐based physically cross‐linked dual‐responsive hydrogel by three steps. First, polyvinyl acetate (PVAc) was grafted onto SA via radical copolymerization. Then, the copolymer was subsequently converted into SA‐g‐poly(vinyl alcohol) (SAPVA) by alcoholysis reaction. PVA content of SAPVA was tailored by controlling the graft percentage of PVAc, i.e. through varying the amount of vinyl acetate during copolymerization. Finally, SAPVA hydrogels were formed by freezing‐thawing cycles. The structure of the graft copolymers was verified with FTIR spectroscopy. X‐ray diffraction analysis results revealed that the crystallinity of SAPVA hydrogels depended on the PVA content of SAPVA. The swelling test showed that SAPVA hydrogels were pH‐responsive, and the swelling was reversible. SAPVA hydrogels also behaved electric‐responsive. In addition, the pH‐sensitivity of SAPVA hydrogels was able to be controlled with the composition of the hydrogels. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Gellan gum‐based novel composite hydrogel: Evaluation as adsorbent for cationic dyes

A semi‐interpenetrating network system [(GG‐g‐PAAm)‐PVA] was made by microwave irradiation of aqueous mixture of gellan gum (GG), acrylamide (AAm), and poly(vinyl alcohol) (PVA) containing N,N′‐methylene‐bis‐acrylamide as crosslinking agent. The gel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, and scanning electron microscopy techniques. The swelling behavior was studied under different pH conditions. A pH‐dependent swelling with maximum swelling under neutral pH was observed. The swelling process is found to follow second‐order kinetics and the mechanism of water transport is found to be Fickian type of diffusion. The (GG‐g‐PAAm)‐PVA was evaluated for removal of dye from aqueous solution, using crystal violet, a cationic dye. The maximum adsorption capacity of the gel was found to be 45.45 mg/g. The kinetic studies revealed a second‐order adsorption process which fits well into Langmuir model. The evaluation of thermodynamic parameters indicated the adsorption process to be exothermic and spontaneous at lower temperatures. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45527.     

Synthesis of pH‐responsive polyethylene terephthalate track‐etched membranes by grafting hydroxyethyl‐methacrylate using atom‐transfer radical polymerization method

pH‐responsive polyethylene terephthalate (PET) track‐etched membranes were synthesized by grafting 2‐hydroxyethyl‐methacrylate (HEMA) on the surface of the membrane via atom transfer radical polymerization. The controllability of grafting polymerization of HEMA on membrane surface is systematically investigated. The pH‐responsive characteristics of PET‐g‐poly(2‐hydroxyethyl‐methacrylate) (PHEMA) gating membranes with different grafted PHEMA chain lengths are measured by tracking the permeation of water solution with different pH values. The results show that the grafting polymerization is controllable, and the permeation of grafted membranes is affected by the grafted PHEMA chain lengths on the surface of membrane. The results also demonstrate that the grafted PET membranes exhibit reversible pH‐response permeation to environmental pH values. Desired pH‐responsive membranes are obtained by controlling the grafted PHEMA chain lengths via atom transfer radical polymerization method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40912.     

Preparation and release behavior of temperature‐ and pH‐responsive chitosan material

BACKGROUND: Chitosan is a polymer with good biocompatibility which makes it promising for potential applications in the field of drug delivery. A novel kind of copolymer, P(CS‐Ma‐graft‐NIPAm), was synthesized with chitosan (CS), maleic anhydride (Ma) and N‐isopropylacrylamide (NIPAm) by grafting and copolymerization. RESULTS: The copolymers were characterized using Fourier transform infrared, ¹H NMR and ultraviolet spectroscopies, and the molecular weight and polydispersity were determined using gel permeation chromatography. The aqueous solution properties of the copolymer and the controlled delivery of coenzyme A from it were also studied. The results showed that the copolymer had temperature and pH sensitivities, and that the release of coenzyme A from the copolymer was dependent on the release medium, namely the concentration of the copolymer, pH and temperature. Higher concentrations of the copolymer absorbed more coenzyme A than lower ones. Increasing temperature accelerated coenzyme A release from the copolymer. Also, the pH of the solution had a significant impact on the release of coenzyme A. CONCLUSION: These results suggest that the novel copolymer could be used in drug delivery systems. Copyright © 2007 Society of Chemical Industry     

Polyacrylamide‐g‐alginate‐based electrically responsive hydrogel for drug delivery application: Synthesis,characterization, and formulation development

An electrically responsive hydrolyzed polyacrylamide‐grafted‐sodium alginate (H‐PAAm‐g‐SA)‐based membrane‐controlled transdermal drug delivery systems were developed and evaluated. The grafting reaction was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. On application of electric stimulus, the swollen H‐PAAm‐g‐SA hydrogel was deswelled in the vicinity of electrodes. The drug release was greater in the presence of electric stimulus when compared with passive diffusion, and it was found to be dependent on the applied electric current strength, concentration of H‐PAAm‐g‐SA copolymer in the reservoir, and cross‐link density of rate‐controlling membrane. A pulsatile pattern of drug release was observed when the electric stimulus was switched “on” and “off.” The skin histopathology study suggested that, after application of an electrical stimulus, changes were in the structure of stratum corneum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Water‐soluble dual responsive polythiophene‐g‐poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate) for different applications

Polythiophene (PT) based dual responsive water‐soluble graft copolymer (PT‐g‐[poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate)]) (PT‐g‐P(MeO₂MA‐co‐DEAEMA)) (PTDE) has been synthesized by random copolymerization of methoxyethoxy ethyl methacrylate (MeO₂MA) and N,N‐diethylamino ethyl methacrylate (DEAEMA) at 30 °C on the 2,5‐poly(3‐[1‐ethyl‐2‐(2‐ bromoisobutyrate)] thiophene) (PTI) macroinitiator using the Cu based atom transfer radical polymerization technique. The PTDE graft copolymer was characterized by gel permeation chromatography and ¹H NMR techniques and it exhibits thermo‐reversible solubility in water showing a lower critical solution temperature of ca 42 °C in neutral aqueous solution. The PTDE graft copolymer contains a fluorescent PT backbone, and interestingly the system exhibits doubling of fluorescence intensity with rising temperature over the temperature range 41–45 °C at pH 7. The PTDE system therefore acts following the principle of the polymeric AND logic gate and it is also found to be effective in sensing of nitroaromatics, particularly picric acid. The influence of chain hydrophobicity on the logic operation and on the sensing of nitroaromatics is discussed. © 2014 Society of Chemical Industry     

Two new types of copolymer membranes controlling clonidine zero‐order release

Two new types of membranes were synthesized by UV curing in our laboratory. The first type of membrane was made of three monomers: 2‐hydroxy‐3‐phenoxypropylacrylate(A), 4‐hydroxybutyl acrylate(B), and 2‐methyl‐2‐nitropropyl methacrylate(C1). The second type of membrane was made of the same monomers A and B, and 2‐butoxyethyl methacrylate(C2). Permeation properties of clonidine releasing through two new types of copolymer membranes were studied. The effects of the ratios of monomers, the thicknesses of membranes, and the concentration of clonidine on the permeation rates were studied. It was found that both copolymer membranes could control clonidine zero‐order release. The permeation rates of the first optimized membrane were linearly dependent on the square root of the drug concentration. The permeation rates of the second optimized membrane had no significant difference when the concentration of clonidine varied in the range of 3.0–5.0 mg mL^?1. Furthermore, both optimized membranes were characterized by FTIR, DSC, and SEM. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Synthesis and characterization of polyacrylamide‐grafted sodium alginate copolymeric membranes and their use in pervaporation separation of water and tetrahydrofuran mixtures

Polyacrylamide‐grafted sodium alginate (PAAm‐g‐Na‐Alg) copolymeric membranes have been prepared, characterized, and used in the pervaporation separation of 10–80 mass % water‐containing tetrahydrofuran mixtures. Totally three membranes were prepared: (1) neat Na‐Alg with 10 mass % of polyethylene glycol (PEG) and 5 mass % of polyvinyl alcohol (PVA), (2) 46 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA, and (3) 93 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA. Using the transport data, important parameters like permeation flux, selectivity, pervaporation separation index, swelling index, and diffusion coefficient have been calculated at 30°C. Diffusion coefficients were also calculated from sorption gravimetric data of water–tetrahydrofuran mixtures using Fick's equation. Arrhenius activation parameters for the transport processes were calculated for 10 mass % of water in the feed mixture using flux and diffusion data obtained at 30, 35, and 40°C. The separation selectivity of the membranes ranged between 216 and 591. The highest permeation flux of 0.677 kg/m² h was observed for 93% grafted membrane at 80 mass % of water in the feed mixture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 272–281, 2002     

Temperature‐sensitive poly(N‐tert‐butylacrylamide‐co‐acrylamide) hydrogels bonded on cotton fabrics by coating technique

Different from the conventional method of developing stimuli‐sensitive textiles by graft copolymerization of environmental responsive polymers onto the fabric, the coating technique was applied to bond temperature‐sensitive hydrogels with cotton fabric through chemical covalent in our work. A temperature‐sensitive linear copolymer of N‐tert‐butylacrylamide (NTBA) and acrylamide (AAm) was prepared in methanol. Then, the cotton fabrics were coated using an aqueous solution of this copolymer containing 1,2,3,4‐butanetertracarboxylic acid as a crosslinker and sodium hypophosphite (SHP) as a catalyst, followed by drying and curing. The surface of the cotton fabrics was bonded on more or less coatings of poly (NTBA‐co‐AAm) hydrogels, as verified by Fourier transform infrared spectroscopy and scanning electron microscopy images. The poly(NTBA‐co‐AAm) hydrogels‐coated fabrics exhibited temperature sensitive, and the temperature interval of the deswelling transition was higher than lower critical solution temperature of linear copolymer solution. The coated fabrics presented good water‐impermeable ability because of the swelling of hydrogels bonded, especially when the add‐on was as high as 14.14%. Environmental scanning electron microscopy images revealed that coating hydrogels swelled and covered on the surface as a barrier to prevent water from penetrating once the coated fabric came into contact with water. The findings demonstrate that the temperature‐sensitive hydrogels can be covalently bonded on the cotton fabrics by coating technique and the coated fabrics have potential on immersion fabrics. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Chlorohydrin water‐swellable rubber compatibilized by an amphiphilic graft copolymer. II. Effects of PVA‐g‐PBA and CPA on water‐swelling behaviors

A water‐swellable rubber (WSR), compatibilized by the amphiphilic graft copolymer, has been prepared by blending chlorohydrin rubber (CHR) with crosslinked polyacrylate (CPA), Poly(vinyl alcohol)‐g‐poly(butyl acrylate) (PVA‐g‐PBA), precipitated silica (PSA), and poly(ethylene glycol) (PEG). The WSR was characterized by scanning electron micrography (SEM). The dependence of the water‐absorbing ratio by weight, the water‐swelling ratio by volume, and the percentage loss by weight on PVA‐g‐PBA and crosslinked polyacrylate contents was investigated. The effect of PVA‐g‐PBA and crosslinked polyacrylate contents on second water‐swelling behaviors and long‐term water‐retention behaviors were also studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3145–3152, 1999     

Novel methyl cellulose‐grafted‐acrylamide/gelatin microspheres for controlled release of nifedipine

Naturally available carbohydrate polymers such as methylcellulose (MC) and gelatin (Ge) have been widely studied in the previous literature for controlled release (CR) applications. In this study, methyl cellulose‐g‐acrylamide/gelatin (MC‐g‐AAm/Ge) microspheres were prepared by water‐in‐oil (W/O) emulsion method and crosslinked with glutaraldehyde to encapsulate with nifedipine (NFD), an antihypertensive drug. The microspheres prepared were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and laser particle size analyzer. DSC thermograms of NFD‐loaded AAm‐MC/Gel microspheres confirmed the molecular level distribution of NFD in the matrix. SEM indicated the formation of spherical particles. Swelling experiments supported the drug diffusion characteristics and release data of the matrices. Cumulative release data were analyzed using an empirical equation to understand the nature of transport of drug through the matrices. Controlled release characteristics of the matrices for NFD were investigated in pH 7.4 media. Drug was released in a controlled manner up to 12 h. Particle size and size distribution of the microspheres as studied by laser light diffraction particle size analyzer indicated their sizes to be around 120 μm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010