Sequential interpenetrating networks

Sjmthesis of the first network, into which are then swollen the reagents to form the second network, which are then reacted. This is a sequential interpenetrating network. 

Figure 23.5 Schematic diagram of the synthesis of PDMS/acrylic acid sequential interpenetrating networks. Adapted from [1].

The first type, termed sequential IPN s, involves the preparation of a crosslinked polymer I, a subsequent swelling of monomer II components and polymerization of the monomer II in situ. The second type of synthesis yields materials known as simultaneous interpenetrating networks (SIN s), involves the mixing of all components in an early stage, followed by the formation of both networks via independent reactions proceeding in the same container (10,11). One network can be formed by a chain growth mechanism and the other by a step growth mechanism. 

Simultaneous Interpenetrating Networks. An interpenetrating polymer network, IPN, can be defined as a combination of two polymers in network form, at least one of which was polymerized or synthesized in the presence of the other (23). These networks are synthesized sequentially in time. A simultaneous interpenetrating network, SIN, is an IPN in which both networks are synthesized simultaneously in time, or both monomers or prepolymers mixed prior to gelation. The two polymerizations are independent and non-interfering in an SIN, so that grafting or internetwork crosslinking is minimized (23-26). 

Figure 1. The synthesis of sequential IPN above and simultaneous interpenetrating networks, SIN, below. For the synthesis of SIN, two different reactions operate simultaneously such as condensation polymerization and addition polymerization. Reproduced with permission from Ref. 23. Copyright 1981, Plenum Publishing.

This is a theoretical study on the structure and modulus of a composite polymeric network formed by two intermeshing co-continuous networks of different chemistry, which interact on a molecular level. The rigidity of this elastomer is assumed to increase with the number density of chemical crosslinks and trapped entanglements in the system. The latter quantity is estimated from the relative concentration of the individual components and their ability to entangle in the unmixed state. The equilibrium elasticity modulus is then calculated for both the cases of a simultaneous and sequential interpenetrating polymer network. 

Development of Multiphase Morphology Sequential Interpenetrating Polymer Networks... 

Interpenetrating polymer networks are defined in their broadest sense as an intimate mixture of two or more pol)Mners in network form [1,2]. Ideally, they can be synthesized by either swelling the first crosslinked polymer with the second monomer and crosslinker, followed by in-situ polymerization of the second component (sequential IPN s) or by reacting a pair of monomers and crosslinkers at the same time through different, non-interfering reaction mechanisms, simultaneous interpenetrating networks, SIN s. In fact, many variations of these ideas exist in both the scientific and the patent literature. In any case, at least one of the two components must have a network structure, as an IPN prerequisite. ... 

Physical hybrids containing silica and polymer are typically interpenetrating networks (IPNs). They can be subdivided into simultaneous or sequential IPNs. The terminology of... 

Abbasi F, Mirzadeh H, Katbab AA (2002) Sequential interpenetrating polymer networks of poly(2-hydroxyethyl methacrylate) and polydimethylsiloxane. J Appl Poly Sci 85(9) 1825—1831... 

Huang G-S, Li Q, Jiang L-X (2002) Structure and damping properties of polydimethylsiloxane and polymethacrylate sequential interpenetrating polymer networks. J Appl Poly Sci 85(3) 545-551... 

J. L. Gomez Ribelles, M. Monleon Pradas, G. Gallego Ferrer, N. Peidro Torres, V. Perez Gimenez, P. Pissis, and A. Kyritsis, Poly(methyl acrylate)/poly(hydroxyethyl acrylate) sequential interpenetrating polymer networks. Miscibility and water sorption behavior, J. Poly. Sci. B 37, 1587-1599 (1999). 

Figure 6.1. Two synthetic methods for preparing interpenetrating polymer networks. A, sequential IPNs, and B, simultaneous interpenetrating networks, SlNs.

BMl) - sequential interpenetrating polymer networks (30 wt.-% BMl, different crosslinker fraction) 85.4 - 130 99Nai... 

Nai Nair, C. P. R., Francis, T., Vijayan, T. M., Krishnan, K. Sequential interpenetrating polymer networks from bisphenol A based cyanate ester and bimaleimide Properties of the neat resin and composites. J. Appl. Polym. Sci. 74 (1999) 2737-2746. 

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