semi-IPN Gel Research Articles

Novel chitosan-poly(N,n-dimethylaminoethyl methacrylate) semi-IPN gels: the synthesis and the antibacterial activities

Novel chitosan-poly(N,n-dimethylaminoethyl methacrylate) semi-IPN gels: the synthesis and the antibacterial activities

Thermosensitive properties of semi-IPN gel composed of amphiphilic gel and zwitterionic thermosensitive polymer in buffer solutions containing high concentration salt

In this study, a semi-interpenetrating polymer network (semi-IPN) gel, which consists of an amphiphilic N,N-dimethylacrylamide- co- N-isopropylacrylamide (DMAA- co-NIPAM) gel and an interpenetrating zwitterionic thermosensitive poly( N-isopropylacrylamide- co- N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate) (poly(NIPAM- co-DMAAPS)) was prepared. The thermosensitive behavior of the semi-IPN gel was investigated in a buffer solution composed of a relatively high concentration of sodium chloride and sodium citrate as salts, and sodium dodecyl sulfate as a surfactant, which are generally used as a buffer solution in biochips. At low temperatures, the semi-IPN gel in the buffer solution was absolutely transparent; however, when the gel was heated, the gel became milky white or opaque without a large change in the gel size. The network of the transparent gel is homogeneous, whereas that of the opaque gel consists of coarse and dense parts. Such a structural change in the gel network was confirmed by the temperature dependence of the permeability of the buffer solution through the semi-IPN gel membrane. The permeability increased drastically when the gel became opaque because of heating.

Gelation and Swelling Behavior of Semi-Interpenetrating Polymer Network Hydrogels Based on Polyacrylamide and Poly(vinyl alcohol)

Novel semi-Interpenetrating Polymer Network (semi-IPN) hydrogels based on partially Hydrolyzed Polyacrylamide (HPAM) and Poly(Vinyl Alcohol) (PVA) were prepared by solution crosslinking using chromium triacetate. Effects of PVA content on the gelation process and swelling behavior in tap water and different electrolyte solutions were investigated. Study of the gelation behavior using dynamic rheometery showed that the limiting storage modulus of the semi-IPN gels decreased with increasing PVA content. It was also found that increasing the PVA content increases the loss factor, indicating that the viscous properties of this gelling system increase more strongly than the elastic properties. The swelling ratio of the semi-IPN gels in tap water decreased as the concentration of the PVA increased. However, the semi-IPN gels showed lower salt sensitivity factor in synthetic oil reservoir water as compared with HPAM gels. Therefore, they are potentially good candidates for enhanced oil recovery applications.

Preparation and characterization of a semi‐interpenetrating network gel polymer electrolyte

AbstractPoly(PEG200 maleate) was synthesized as a new type crosslinkable prepolymer and the semi‐interpenetrating polymer network (semi‐IPN) gel electrolytes were prepared by means of thermal polymerization. Their intrinsic properties were characterized by FTIR spectroscopy, differential scanning calorimetry (DSC), X‐ray diffractions (XRD), scanning electron microscopy, alternating current impedance (AC impedance), and linear sweep voltammetry. The prepared polymer hosts are transparent and have good mechanical properties. The results of DSC and XRD confirm that the prepared hosts are in amorphous state and they can hold enough liquid electrolytes, which is favorable for Li+ ions to transport via both the absorbed liquid electrolyte and the gel of the entire systems. The semi‐IPN gel electrolytes exhibit high ionic conductivity on the order of 10−3 S cm−1. Their electrochemical stability up to +4.6 V against Li+/Li also makes them potential candidates for application as polymer electrolytes in devices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Synthesis and Temperature-Responsive Properties of Novel Semi-interpenetrating Polymer Networks Consisting of a Poly(acrylamide) Polymer Network and Linear Poly(acrylic acid) Chains

A novel semi-interpenetrating polymer network (semi-IPN) gel consisting of an AAm gel and linear PAAc chains was designed and developed. The semi-IPN gel was simply prepared by infiltrating PAAc chains into AAm gel networks from an outer PAAc solution through immersion of AAm gels in the PAAc solution. The semi-IPN gel swelled at higher temperature and shrunk at lower temperature. Swelling-ratio transition temperatures of the semi-IPN gel shifted to lower values with increasing pH of the surrounding PAAc solution. The swelling-ratio transition of the semi-IPN gel became sharper with higher-molecular-weight PAAc. These swelling-ratio changes were completely reversible. A prototype of a light modulator was fabricated utilizing semi-IPN microgel particles containing 20 wt % of carbon black pigment. The transmittance of the light modulator was altered from 63 to 8% when the light modulator was heated from 10 to 60 °C.

New design for a safe lithium-ion gel polymer battery

We present a new design of a lithium-ion gel polymer battery which is fabricated using a semi-interpenetrating network (semi-IPN) type gel polymer and LiCoO 2, covered by an ion conductive polyurethane. A 7 wt.% solution of a semi-IPN gel polymer, composed of a fully cyanoethylated cellulose derivative and multifunctional poly(oxyethylene)methacrylate has an ionic conductivity of 2.7 × 10 −3 S cm −1 at 25 °C, and has a higher degree of control of liquid electrolyte evaporation when compared with conventional fluoride polymer gels. Another ion conductive polymer, a caprolactone segmented polyurethane, arranged on the surface of the cathode active material in order to increase the start temperature of the thermal runaway reaction worked as planned, raising the exothermic decomposition temperature by 50 °C. A large (2500 mAh) cell showed good discharge performance and improved safety characteristics as judged by a nail penetration test. Furthermore, this battery system exhibited a unique phenomenon, that of preventing overcharging. The new design of this lithium-ion gel polymer battery could be promising for large batteries that must be inherently safe, such as batteries for mobile applications.

Fluorescence study on the mechanism of rapid shrinking of grafted poly( N-isopropylacrylamide) gels and semi-IPN gels

In order to clarify in nanometer scale the mechanism of rapid shrinking of grafted poly( N-isopropylacrylamide) (PNIPAM) hydrogels during temperature jump from room temperature to 40 °C, temperature dependences of dansyl fluorescence were studied for the rapid-shrinking grafted PNIPAM gels in which dansyl groups are attached to graft chains or network main chains. Gradual decrease in dansyl fluorescence peak wavelength, λ f, with the increase in temperature between 17 and 32 °C for grafted chains in the grafted PNIPAM gel from 540 to 500 nm showed the occurrence of coil-globule transition of graft chains during this temperature range. However, λ f of network main chains showed abrupt decrease at 30–34 °C from 540 to 510 nm reproducing the macroscopic volume phase transition of PNIPAM gels. The coil-globule transition and further aggregation of graft chains enhance the formation of heterogeneous structure during the temperature jump, providing water-expelling channels at the surface skin layer of the collapsed PNIPAM gel. The possible importance of large-scale heterogeneity with a much larger size than the mesh size of network on the rapid-shrinking is suggested, because this type of large-scale heterogeneity can be introduced by the network formation in the presence of linear macromonomer. A post-crosslinked semi-IPN gel also showed rapid shrinking and gradual decrease in λ f for the linear polymer chains inside.