Swelling and diffusion characteristics of novel semi‐interpenetrating network hydrogels composed of poly[(acrylamide)‐ co‐(sodium acrylate)] and poly[(vinylsulfonic acid), sodium salt]

A series of novel semi‐interpenetrating polymer networks (IPNs) composed of poly[(acrylamide)‐co‐(sodium acrylate)] with varying amounts (5, 10, and 15 wt%) of poly[(vinylsulfonic acid), sodium salt] was synthesized. The semi‐IPN hydrogels were characterized by infrared spectroscopy. The swelling behavior of these IPNs was studied in distilled water/physiological solutions/buffer solutions/salt solutions. As the amount of poly[(vinylsulfonic acid), sodium salt] increased in the network, the swelling capacity of the semi‐IPNs increased considerably. The swelling and diffusion characteristics such as water penetration velocity (v), diffusion exponent (n), and diffusion coefficient (D) were calculated in distilled water, as well as in other physiological solutions. The highest swelling capacity was noted in urea and glucose solutions. The semi‐IPN hydrogels followed non‐Fickian diffusion behavior in water and physiological fluids, whereas Fickian behavior was observed in buffer solutions. The stimuli‐responsive characteristics towards physiological fluids, salt concentration, and temperature of these semi‐IPN hydrogels were also investigated. The swelling behavior of the semi‐IPNs decreased markedly with an increase of the concentration of the salt solutions. Copyright © 2006 Society of Chemical Industry     

Poly(vinyl alcohol) Based pH Responsive Semi-IPN Hydrogels: A Comparative Swelling Investigation

The semi-interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and random copolymers of poly(acrylamide-co-sodium methacrylate), poly(AAm-co-NMA); poly(acrylamide-co-potassium methacrylate), poly(AAm-co-KMA); poly(acrylamide-co-maleic acid), poly(AAm-co-MA) were prepared by conventional co-polymerization employing ammonium persulphate (APS)/N,N,N¹,N¹-tetraethylmethylenediamine (TMEDA) as redox initiating system in presence of N,N¹-methylenebisacrylamide (MBA) as a crosslinker. The swelling behavior of these semi-IPN hydrogels were compared in detail in various swelling media, including different pH, salt, and biological fluids.     

Preparation and swelling behavior of macroporous poly(acrylamide‐co‐sodium methacrylate) superabsorbent hydrogels

Macroporous superabsorbent hydrogels (SAHs) composed of acrylamide (AAm) and sodium methacrylate (NMA) were prepared by aqueous solution polymerization in the presence of a glucose solution. Their swelling capacity was investigated as a function of the concentrations of the glucose solution, sodium methacrylate, crosslinker, initiator, and activator. The porosity of the poly(acrylamide‐co‐sodium methacrylate) superabsorbent hydrogels was confirmed using scanning electron microscopy. The SAHs were characterized by IR spectroscopy. To estimate the effect on the swelling behavior, three types of crosslinkers were employed: N,N′‐methylenebisacrylamide, 1,4‐butanediol diacrylate, and diallyl phthalate. Network structural parameters such as initial swelling rate, swelling rate constant, and maximum equilibrium swelling were evaluated by water absorption measurement. The equilibrium water content (EWC%) of the AAm–NMA macroporous SAHs was found to be in the range of 93.31–99.68, indicating that these SAHs may have applications as biomaterials in the medicinal, pharmaceutical, and veterinary fields. Most of the SAHs prepared in this investigation followed non‐Fickian‐type diffusion, and few followed a case II– or super–case II‐type diffusion. The diffusion coefficients of these macroporous SAHs were investigated. Further, the swelling behavior of these SAHs also was investigated at different pHs and in different salt solutions and simulated biological fluids. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3202–3214, 2006     

Dye Sorption and Water Uptake Properties of Crosslinked Acrylamide/Sodium Methacrylate Copolymers and Semi-Interpenetrating Polymer Networks Composed of PEG

A series of novel semi-interpenetrating polymer networks hydrogels composed of poly(ethylene glycol) and random copolymer of acrylamide/sodium methacrylate were prepared by polymerization of aqueous solution of acrylamide, sodium methacrylate using ammonium persulphate/N,N,N′,N′-tetramethylethylenediamine as a redox-initiating pair in the presence of poly(ethylene glycol) and poly(ethylene glycol)diacrylate as crosslinker. Fourier Transform Infrared spectroscopy was used to identify the presence of different repeating units in the semi IPNs. Water uptake and dye-sorption properties of acrylamide/sodium methacrylate hydrogels and acrylamide/sodium methacrylate/poly(ethylene glycol) semi IPNs were investigated as a function of chemical composition of the hydrogels. Cationic dye, Janus Green B have been used in sorption studies as a model molecule. This study has given the quantitative information on the swelling and sorption characteristic of acrylamide/sodium methacrylate hydrogels and acrylamide/sodium methacrylate/poly(ethylene glycol) semi IPNs in many potential applications.     

Swelling behaviors of ionic poly(N,N‐dimethylacrylamide‐co‐acrylamide) hydrogels in various media

Polyelectrolyte hydrogels were synthesized from N,N‐dimethylacrylamide, acrylamide, and itaconic acid with ammonium persulfate as a free‐radical initiator in the presence of methylene(bis)acrylamide as a crosslinker. The swelling behavior of the ionic poly(N,N‐dimethylacrylamide‐co‐acrylamide) hydrogels was investigated in pure water, in KSCN solutions with pHs 4 and 9, and in water–acetone mixtures according to the itaconic acid content in the hydrogel. The pulsatile swelling behavior of these hydrogels was studied both in water–acetone and in pH 2–9 buffer solutions. Although the equilibrium swelling ratio of the hydrogels with low concentrations of itaconic acid was almost not affected by changes in the temperature, the equilibrium swelling ratio of the hydrogels with high concentrations of itaconic acid increased in the temperature range of 20–50°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2140–2145, 2007     

Synthesis and swelling behavior of thermosensitive IPN hydrogels based on sodium acrylate and N‐isopropyl acrylamide by a two‐step method

A series of interpenetrating polymer network (IPN) hydrogels having higher swelling ratio (SR) and thermosensitivity were synthesized from sodium acrylate (SA) and N‐isopropyl acrylamide (NIPAAm) by a two‐step method. A series of the porous poly(sodium acrylate ‐co‐1‐vinyl–2‐pyrrolidone) [poly(SA‐co‐VP)], (SV), hydrogels were prepared from acrylic acid having 90% degree of neutralization and VP monomer in the first step. The second step is to immerse the SV dried gels into the NIPAAm solution containing initiator, accelerator, and crosslinker to absorb NIPAAm solution and then polymerized to form the poly(SA‐co‐VP)/poly(NIPAAm) IPN hydrogels (SVN). The effect of the different molar ratios of SA/VP and the content of NIPAAm on the swelling behavior and physical properties of the SVN hydrogels was investigated. Results showed that the SVN hydrogels displayed an obviously thermoreversible behavior when the temperature turns across the critical gel transition temperature (CGTT) of poly(NIPAAm) hydrogel. The pore diameter distributions inside the hydrogel also indicated that the pore sizes inside the SVN hydrogels were smaller than those inside the SV hydrogels. At the same time, the more proportion of SA was added into the hydrogel, the larger pore diameter of the SV hydrogel was formed. The results also showed that the SR decreased with an increase of the VP content in the SV hydrogel and more obviously decreased in the SVN hydrogels. The SVN networks also showed stronger shear moduli than SV hydrogels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Behavior of semi IPN hydrogels composed of PEG and AAm/SMA copolymers in swelling and uptake of Janus Green B from aqueous solutions

Semi-interpenetrating polymer network (semi IPN) hydrogels of poly(ethylene glycol; PEG) were prepared as a water adsorbent for dye (Janus Green B) sorption. For this, PEG and copolymer of acrylamide/sodium methacrylate (AAm/SMA) were prepared by polymerization of aqueous solution of acrylamide (AAm), sodium methacrylate (SMA) using ammonium persulfate (APS)/N,N,N′,N′-tetramethylethylenediamine (TEMED) as redox initiating pair in presence of PEG and poly(ethylene glycol)dimethacrylate (PEGDMA) as crosslinker. FTIR spectroscopy was used to identify the presence of different repeating units in the semi IPNs. Some swelling and diffusion characteristics were calculated for different semi IPNs and hydrogels prepared under various formulations. Water uptake and dye sorption properties of AAm/SMA hydrogels and AAm/SMA/PEG semi IPNs were investigated as a function of chemical composition of the hydrogels. Janus Green B have used in sorption studies. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and properties of silver nanoparticles in chitosan‐based thermosensitive semi‐interpenetrating hydrogels

In this article, thermosensitive poly(N‐isopropyl acrylamide‐co‐vinyl pyrrolidone)/chitosan [P(NIPAM‐co‐NVP)/CS] semi‐interpenetrating (semi‐IPN) hydrogels were prepared by redox‐polymerization using N,N‐methylenebisacrylamide as crosslinker and ammonium persulfate/N,N,N′,N′‐tetramethylethylenediamine as initiator. Highly stable and uniformly distributed Ag nanoparticles were prepared by using the semihydrogel networks as templates via in situ reduction of silver nitrate in the presence of sodium borohydride as a reducing agent. Introduction of CS improves the hydrogels swelling ratio (SR) and stabilizes the formed Ag nanoparticles in networks. Scanning electron microscopy and transmission electron microscopy revealed that Ag nanoparticles were well dispersed with diameters of 10 nm. The semi‐IPN hydrogel/Ag composites had higher SR and thermal stability than its corresponding semi‐IPN hydrogels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

pH‐ and temperature‐responsive IPN hydrogels based on soy protein and poly(N‐isopropylacrylamide‐co‐sodium acrylate)

pH‐ and temperature‐responsive interpenetrating polymer network (IPN) hydrogels based on soy protein and poly(N‐isopropylacrylamide‐co‐sodium acrylate) were successfully prepared. The structure and properties of the hydrogels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analyzer. The equilibrium and dynamic swelling/deswelling behaviors and the drug release properties of the hydrogels responding to pH and/or temperature were also studied in detail. The hydrogels have the porous honeycomb structures, good miscibility and thermal stability, and good pH‐ and temperature‐responsivity. The volume phase transition temperature of the hydrogels is ca. 40°C. Changing the soy protein or crosslinker content could be used to control the swelling behavior and water retention, and the hydrogels have the fastest deswelling rate in pH 1.2 buffer solutions at 45°C. Bovine serum albumin release from the hydrogels has the good pH and temperature dependence. The results show that the proposed IPN hydrogels may have potential applications in the field of biomedical materials such as in drug delivery systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39781.     

Interpenetrating polymer networks of poly(butyl methacrylate) and poly(α‐terpineol‐co‐styrene): Synthesis and characterization

Simultaneous interpenetrating polymer networks (IPNs) based on poly(butyl methacrylate) and poly(α‐terpineol‐co‐styrene) were synthesized with azobisisobutyronitrile (AIBN) as the initiator and divinyl benzene as the crosslinking agent in xylene under an inert nitrogen atmosphere. Fourier transform infrared spectra provided structural evidence for the IPNs, indicating characteristic frequencies of ester groups of butyl methacrylate at 1723 cm^?1 and alcoholic groups of α‐terpineol at 3436 cm^?1. Scanning electron microscopy revealed threadlike network structures. Properties such as percentage swelling and average molecular weight between crosslinks were direct functions of the copolymer and initiator (AIBN) concentrations and inverse functions of the monomer (butyl methacrylate) and crosslinking agent (divinyl benzene) concentrations. Differential scanning calorimetry showed an IPN glass‐transition temperature at 80.2°C. The thermal decompositions of the IPNs were established with the help of thermogravimetric analysis. The value of the activation energy, calculated from thermogravimetric analysis with the Coats and Redfern equation, was 23 kJ/mol. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 343–352, 2006     

Synthesis and network parameters of hydrophobic poly(N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐lauryl acrylate) hydrogels

Hydrophobic poly(N‐[3‐(dimethylaminopropyl)]methacrylamide‐co‐lauryl acrylate) [P(DMAPMA‐co‐LA)] hydrogels with different LA content were synthesized by free‐radical crosslinking copolymerization of corresponding monomers in water by using N,N‐methylenebis(acrylamide) as the crosslinker, ammonium persulfate as the initiator, and N,N,N′,N′‐tetramethylethylenediamine as the activator. The swelling equilibrium of the hydrogels was investigated as a function of temperature and hydrophobic comonomer content in pure water. An interesting feature of the swelling behavior of the P(DMAPMA‐co‐LA) hydrogels with low LA content was the reshrinking phase transition where the hydrogels swell once and collapse as temperature was varied in the range of 30–40°C. The average molecular mass between crosslinks (M?_c) and polymer–solvent interaction parameter (χ) of the hydrogels were calculated from equilibrium swelling values. The enthalpy (ΔH) and entropy (ΔS) changes appearing in the χ parameter for the hydrogels were determined by using the Flory–Rehner theory based on the phantom network model of swelling equilibrium. The positive values for ΔH and ΔS indicated that the hydrogels had a positive temperature‐sensitive property in water, that is, swelling at a higher temperature and shrinking at a lower temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4159–4166, 2006     

Preparation and properties of temperature‐sensitive soy protein/poly(N‐isopropylacrylamide) interpenetrating polymer network hydrogels

Temperature‐sensitive interpenetrating polymer network (IPN) hydrogels based on soy protein and poly(N‐isopropylacrylamide) were successfully prepared. The structure and properties were systematically characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis, and the swelling and deswelling behavior was also investigated. It was found that the hydrogels had good miscibility, thermal stability and temperature sensitivity, and the lower critical solution temperature was ca 32 °C. Changing the content of soy protein or crosslinker could be used to control the swelling behavior, water retention and network structure of the IPN hydrogels. The results show that the novel IPN hydrogels may be of potential interest in drug delivery systems. Copyright © 2011 Society of Chemical Industry     

Synthesis and characterization of pH‐ and temperature‐sensitive silk sericin/poly(N‐isopropylacrylamide) interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) composed of silk sericin (SS) and poly(N‐isopropylacrylamide) (PNIPAAm) were prepared simultaneously. The properties of the resultant IPN hydrogels were characterized by differential scanning calorimetry and SEM as well as their swelling behavior at various temperatures and pH values. The single glass transition temperature (T_g) presented in the IPN thermograms indicated that SS and PNIPAAm form a miscible pair. The swollen morphology of the IPNs observed by SEM demonstrated that water channels (pores present in SEM micrographs) were distributed homogeneously through out the network membranes. The swelling ratio of the IPNs depended significantly on the composition, temperature and pH of the buffer solutions. The dynamic transport of water into the IPN membrane was analyzed based on the Fickian equation. Copyright © 2006 Society of Chemical Industry     

Thermal characteristics of poly(vinyl alcohol) and poly(vinylpyrrolidone) IPNs

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and 1‐vinyl‐2‐pyrrolidone (VP) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depressions of the melting temperatures of PVA segments in IPNs were observed with increasing VP content via the DSC. The DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated using TGA and appeared at near 270°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1844–1847, 2002     

Swelling kinetics of modified poly(vinyl alcohol) hydrogels

Interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and monomer, N‐isopropylacrylamide (NIPAAm), diallyldimethylammonium chloride (DADMAC), or methacrylic acid (MAA) were prepared by using the sequential‐IPN method. The equilibrium swelling ratios of PVA/NIPAAm (VANP), PVA/DADMAC (VADC), and PVA/MAA (VAMA) are 412, 370, and 297 at 25°C, respectively. VANP had the highest swelling ratio in time‐dependent swelling behavior, whereas the swelling ratio of VAMA had the lowest. The n values of VANP, VADC, and VAMA are 0.72, 0.81, and 0.96, respectively. Transport of all IPN hydrogels is anomalous and their transport mechanisms are dominated by a combination of diffusion‐controlled and relaxation‐controlled systems. VAMA has the highest activation energy and VANP has the lowest activation energy. The values of all IPN hydrogels are from 4.66 to 16.49 kJ/mol, which proves that all IPN hydrogels are hydrophilic. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3310–3313, 2003     

Environmental responses of poly(N‐isopropylacrylamide‐co‐glycidyl methacrylate derivatized dextran) hydrogels

A series of intelligent hydrogels (poly(NIPA‐co‐GMA‐Dex)) were synthesized by copolymerization of N‐isopropylacrylamide (NIPA) and glycidyl methacrylate derivatized dextran (GMA‐Dex) in aqueous solution with different ratios. Their swelling behaviors at different temperatures and in different pH and ionic strengths, and their mechanical properties were studied. It has found that poly(NIPA‐co‐GMA‐Dex) hydrogels are temperature‐, pH‐, and ionic strength‐sensitive associated with the roles of the component PNIPA and GMA‐Dex, respectively. Most significantly, poly (NIPA‐co‐GMA‐Dex) hydrogels exhibit simultaneously good swelling properties and mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2435–2439, 2005     

Development and characterization of thermosensitive hydrogels based on poly(N‐isopropylacrylamide) and calcium alginate

This work refers to the synthesis and characterization of thermosensitive hydrogels based on interpenetrating polymer networks (IPNs) of poly(N‐isopropylacrylamide) (PNIPAAm) and calcium alginate in the form of films. The influence of the crosslinking degree of PNIPAAm and alginate content on thermal, swelling, mechanical, and morphological properties of hydrogels is investigated in detail. Characterization of pure PNIPAAm hydrogels and IPN hydrogels was performed by FTIR, DSC, DMA, and SEM. In addition, the studies of equilibrium swelling behavior as well as swelling, deswelling, and reswelling kinetics are performed. The results obtained imply the benefits of synthesizing IPNs based on PNIPAAm and calcium alginate over pure PNIPAAm hydrogels. The presence of calcium alginate contributes to the improvement of mechanical properties, the deswelling rate of hydrogels, and the network porosity, without altering the thermosensitivity of PNIPAAm significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Determination of swelling behavior and morphological properties of poly(acrylamide‐co‐itaconic acid) and poly(acrylic acid‐co‐itaconic acid) copolymeric hydrogels

Poly(acrylamide‐co‐itaconic acid) (PAAmIA) and poly(acrylic acid‐co‐itaconic acid) (PAAIA) copolymeric hydrogels were prepared with different compositions via free‐radical polymerization. Ethylene glycol dimethacrylate (EGDMA) was used as an original crosslinker for these monomers. Gelation percentages of the monomers were studied in detail and it was found that addition of IA into the monomer mixture decreased the gelation percentage. The variation in swelling values (%) with time, temperature, and pH was determined for all hydrogels. PAA, which is the most swollen hydrogel, has the swelling percentage value of 2000% at pH = 7.4, 37°C. Swelling behaviors were explained with detailed SEM micrographs, which show the morphologic differences between dry and swollen hydrogels. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5994–5999, 2006     

Carrageenan‐g‐poly(acrylamide)/poly(vinylsulfonic acid,sodium salt) as a novel semi‐IPN hydrogel: Synthesis,characterization, and swelling behavior

A semi‐interpenetrating polymer network (semi‐IPN) hydrogel based on kappa‐carrageenan (κC) and poly (vinylsulfonic acid, sodium salt) (PVSA) was prepared by graft copolymerization of acrylamide (AAm) using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. FTIR spectroscopy was used for confirming the structure of the final product. It was found that the chemical composition of the Semi‐IPN hydrogel is equal to the initial homopolymers and monomer feed compositions. The swelling capacity of the hydrogel was shown to be affected by the MBA, APS, and AAm concentration as well as κC/PVSA weight ratio. The swelling behavior of the hydrogel was also investigated in various pHs and salt solutions. Since the highly swelling biopolymer‐based hydrogel exhibits low salt‐sensitivity, it may be referred to as an anti‐salt superabsorbent hydrogel. The swelling kinetics of the superabsorbent hydrogels was studied as well. POLYM. ENG. SCI., 47:1388–1395, 2007. © 2007 Society of Plastics Engineers     

Temperature‐responsive characteristics of poly(N‐isopropylacrylamide) hydrogels with macroporous structure

Macroporous poly(N‐isopropylacrylamide) (PNIPA) hydrogels were synthesized by free‐radical crosslinking polymerization in aqueous solution from N‐isopropylacrylamide monomer and N,N‐methylenebis (acrylamide) crosslinker using poly(ethylene glycol) (PEG) with three different number‐average molecular weights of 300, 600 and 1000 g mol^?1 as the pore‐forming agent. The influence of the molecular weight and amount of PEG pore‐forming agent on the swelling ratio and network parameters such as polymer–solvent interaction parameter (χ) and crosslinking density (ν_E) of the hydrogels is reported and discussed. Scanning electron micrographs reveal that the macroporous network structure of the hydrogels can be adjusted by applying different molecular weights and compositions of PEG during polymerization. At a temperature below the volume phase transition temperature, the macroporous hydrogels absorbed larger amounts of water compared to that of conventional PNIPA hydrogels, and showed higher equilibrated swelling ratios in aqueous medium. Particularly, the unique macroporous structure provides numerous water channels for water diffusion in or out of the matrix and, therefore, an improved response rate to external temperature changes during the swelling and deswelling process. These macroporous PNIPA hydrogels may be useful for potential applications in controlled release of macromolecular active agents. Copyright © 2006 Society of Chemical Industry