Interpenetrating polymer networks basis

A novel interpenetrating polymer network (IPN) of polyethylene glycol, polyvinyl alcohol and polyacrylamide is prepared and its potential for sorption and delivery of diatase, a digestive enzyme, is evaluated. The effects of experimental parameters such as varying chemical composition of the IPN, percent loading of diatase, pH and temperature of the release medium and molecular weight of PEG are investigated on the release dynamics of the diatase. On the basis of Pick s equation, the diffusional exponent (n) and diffusion (D) are evaluated for different IPN compositions. From the kinetic parameters data, an attempt is made to explore the nature of the mechanism of the release process of diastase. The IPNs are characterised by IR and examined for zero-order release behaviour of loaded enzyme. 39 refs. 

If two or more monomeric units are used to make one polymer, a copolymer is formed. The statistical, random, alternating, and periodic copolymers show the relationship of two mers on an individual basis. The block, graft, AB-cross-linked, and interpenetrating polymer network copolymers comprise large portions of chain or chains containing only one mer. It must be pointed out that each of these may be subject to being composed of the various tac-ticities and so forth that describe the configurational properties. 

T. E. Lipatova, V. V. Shilov, N. P. Bazilevskaya, and Yu. S. Lipatov, The Formation of Interpenetrating Polymeric Networks on the Basis of Oligoester Acrylate, Styrene, and Divinylbenzene by an Anionic Mechanisms, Br. Polym. J. 9(2), 159 (1977). Oligoester acrylate/PS anionically prepared IPNs. 

V. V. Shilov, Yu. S. Lipatov, L. V. Karabanova, and L. M. Sergeeva, Phase Separation in the Interpenetrating Polymeric Networks on the Basis of Polyurethane and Polyurethane Acrylates, J. Polym. Sci. Polym. Chem. Ed. 17, 3083 (1979). Small-angle X-ray study. Thickness of transition layer, diffuseness of phase boundary, degree of miscibility determined. 

Heterogeneous polymeric sterns on the basis of two polymers can be also realized in the form of interpenetrating polymeric networks 155,156). Such systems are interesting in that they consist of two continuous, not chemically inter-connecting polymeric networks which cannot be separated because of mutual penetration of segments of one network into the cells of the other. The appearance in IPN of a transitional region caused by the incompatibility of the components increases the heterr neity of such systems and can be noted on their viscoelastic properties (157). 

Continuity can also be reached by polymerizing one of the components within the other. In such a case the blend is called an IPN, an interpenetrating network it is, in most cases formed by a thermoset in a thermoplastic polymer. An example is a compound built-up from 50% of a thermoplast (polycarbonate or polysulphone), and 50% of a cross-linked polymer on the basis of dicyanate bisphenol-A. The skeleton... 

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