Recent Developments in Interpenetrating Polymer Networks and Related Materials

Abstract

An interpenetrating polymer network, IPN, is defined as a combination of two polymers in network form, at least one of which is synthesized and/or cross-linked inthe immediate presence of the other. In this chapter, the literature and patents on IPNs are reviewed from 1979 to the present. Many compositions contain two continuous phases, which contribute to their toughness. A new area of IPN interest is the thermoplastic IPN concept, where the IPNs have physical rather than chemical cross-links..A.N INTERPENETRATING POLYMER NETWORK, IPN, previously was defined as a combination of two polymers in network form, at least one of which is synthesized and/or cross-linked in the immediate presence of the other (I). Although this definition still fits most materials called IPNs, now some hybrid compositions, such as the thermoplastic IPNs, call for a broader view. This chapter will review the IPN literature from 1979 to the present. The choice of year 1979 is dictated by the advent of several reviews covering the literature up to that time (1-4). During the 1960s and 1970s, several synthetic methods were developed to prepare IPNs. These methods include materials now called sequential IPNs, where the networks are made sequentially, and simultaneous interpenetrating networks, SINs, where both monomers are mixed together and polymerized by independent and noninterfering routes. Surprisingly, most workers find it is better to polymerize one of the two networks in an SIN faster than the other, as will be explored further. Other methods of synthesis include latex IPNs, where both networks are on each latex particle, and interpenetrating elastomeric networks, IENs, where two latexes are mixed and subsequently cross-linked.

Miscibility, Hierarchical Structures, and Enhanced Mechanical Properties of Acrylic Rubber by the Formation of a Chemically and Physically Crosslinked Partially Miscible Interpenetrating Polymer Network with Poly(vinylidene fluoride)

“…The degree of equilibrium swelling was measured by weight, and the obtained values were transformed to the values measured by volume using the densities of DMAc (0.937 g•cm −3 ) and ACM (1.11 g•cm −3 ). 32 Network-chain density (ν) was obtained using the Flory−Rehner equation 33 (1) where ϕ denotes the volume fraction of crosslinked ACM in the swollen state, ϕ 0 represents the volume fraction of the crosslinked ACM in the dry state (ϕ 0 = 1), V s denotes the molar volume of DMAc (81.6 cm 3 •mol −1 ), and χ represents the Flory interaction parameter. χ was calculated as 0.33 at 25 °C using the Hansen solubility parameters of ACM 34 and DMAc, 35 where ACM was substituted by PEA as the major component of ACM.…”

“…Interpenetrating polymer networks (IPNs) are defined as the combinations of two or more network polymers, at least one of which is synthesized and/or crosslinked in the immediate presence of the others . Owing to the physical entanglement caused by the unusual macromolecular architectures, the synergistic improvements in, e.g., mechanical properties , and damping behavior, have been reported previously.…”

Step Polymerization

“…An IPN is obtained by the simultaneous or sequential crosslinking of two different polymer systems [Kim et al, 1986;Klempner and Berkowski, 1987;Sperling, 1981Sperling, , 1986Sperling, , 1997. IPN synthesis is the only way of achieving the equivalent of a physical blend for systems containing crosslinked polymers.…”

Phase-Separated Interpenetrating Polymer Networks

“…5) produce bigger domains. The domain size also depends on the reaction time and the formation rates of each [15] network. Only when the relative formation rates of both networks become close to each other are the sizes of the domains moderate and both phases can attain larger cross-linking density.…”

“…Sperling [15] defines IPNs as a "combination of two polymers in network form, at least one of which is synthesized and/or cross-linked in the immediate presence of the other". This definition has nothing in common with catenanes or interpenetration between two components on a molecular level.…”