Poly -acrylate hydrogels

There was some interest in making a gel using acrylic acid and its salts. Iwakura et al. reported on an EDLC capacitor using a cross-linked potassium poly(acrylate) hydrogel. ° The capacitance with a polymer electrolyte was 150 F/g, which was a little higher than with the aqueous KOH electrolyte (144 F/g).The effect was attributed to pseudocapacitance owing to the use of the hydrogel in the capacitor cell. Moreover, the capacitance retention after 20000 cycles was found to be 82% of the initial capacitance for the polymer-based electrolyte while it was only 72% for the aqueous KOH electrolyte. 

The two matrices in these cements are of a different nature an ionomer salt hydrogel and polyHEMA. For thermodynamic reasons, they do not interpenetrate but phase-separate as they are formed. In order to prevent phase separation, another version of resin glass polyalkenoate cement has been formulated by Mitra (1989). This is marketed as VitraBond, which we term a class II material. In these materials poly(acrylic acid), PAA, is replaced by modified PAAs. In these modified PAAs a small fraction of the pendant -COOH groups are converted to unsaturated groups by condensation reaction with a methacrylate containing a reactive terminal group. These methacrylates can be represented by the formula ... 

Surface Heparinization of Poly(ethylene terephthalate) Films Modified with Acrylic Hydrogels... 

The aim of this paper is to report the bonding of heparin on poly(ethylene terephthalate) films containing an acrylic hydrogel (pHEMA), the method of preparation of the support material and some of its properties. 

Hydrogels that have the ability to respond to pH changes have been studied extensively over the years. These gels typically contain side ioni-zable side groups such as carboxylic acids or amine groups (Oppermann, 1992 Scranton et al., 1995). The most commonly studied ionic polymers include polyacrlyamide (PAAm), poly(acrylic acid) (PAA), poly(metha-crylic acid) (PMAA), poly (diethylaminoethyl methacrylate) (PDEAEMA), and poly(dimethylaminoethyl methacrylate) (PDMAEMA). 

Similarly, fluorescent silver clusters could be prepared in so called molecular hydrogels, formed by polyglycerol-b/oc -poly(acrylic acid) (PG-b-PAA), using a ratio COOH Ag of 2 1 with UV irradiation (365 nm). The emission band centered at 590 nm reached a maximum after 200 min of irradiation. The authors claim improved photostability of the clusters since they are still luminescent even after 9 h of irradiation, but it has to be mentioned that the irradiation source was weak, only 0.5 mW/cm2. They claim that it is the number of arms in the star polymer rather than the length of the arms (thus the density of COOH) that plays a crucial role in the formation of silver clusters [30]. 

Shen Z, Duan H, Frey H (2007) Water-soluble fluorescent ag nanoclusters obtained from multiarm star poly(acrylic acid) as molecular hydrogel templates. Adv Mater 19 349-352... 

The main reason that poly(acrylic acid) and poly(methacrylic acid) hydrogels and hydrogel particles have been utilized in oral drug delivery is the fact that they also possess bioadhesive properties (Park and Robinson 1987). Bioadhesive polymers... 

Park, H. and Robinson, J.R. (1987). Mechanisms of mucoadhesion of poly(acrylic acid) hydrogels. Pharmaceut. Res., 4, 457-64. 

Garcia-Gonzalez, N., et al., Design and evaluation of buccoadhesive metoclopramide hydrogels composed of poly(acrylic acid) cross linked with sucrdafe.J. Pharm., 100, 65,1993. 

N. S. Patil, J. S. Dordick, and D. G. Rethwisch, Macroporous poly(sucrose acrylate) hydrogel for controlled release of macromolecules, Biomaterials, 17 (1996) 2343-2350. 

Another area in which smart hydrogels are likely to find application is the development of more efficient drug delivery systems. One material that has showed promise in this held is called Pluronic-PAA. Its trade name is Smart Hydrogel . The material is a mixture of two polymers, one of which is poly(acrylic acid) (PAA), which attaches readily to other biological materials and is responsive to changes in pH. The other polymer is a copolymer of poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO). This copolymer belongs to a family of polymers known by the trade name of Pluronic polymers. 

A. Kyritsis, P. Pissis, J. L. Gomez Ribelles, and M. Monleon Pradas, Polymer-water interactions in poly(hydroxyethyl acrylate) hydrogels studied by dielectric, calorimetric and sorption isotherm measurements, Polym. Gels Networks 3, 445-469 (1995). 

G. Gallego Ferrer, J. M. Soria Melia, J. Hernandez Canales, J. M. Meseguer Duenas, F. Romero Colomer, M. Monleon Pradas, J. L. Gomez Ribelles, P. Pissis, and G. Polizos, Poly(2-hydroxyethyl acrylate) hydrogel confined in a hydrophobous porous matrix. Colloid Polym. Sci. 283, 681-690 (2005). 

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