Sequential interpenetrating polymer networks, synthesis

Goswami, S., Chakrabarty, D. Synthesis and characterization of sequential interpenetrating polymer networks of novolac resin and poly(ethyl acrylate). J. Appl. Polym. Sci. 99, 2857-2867 (2006)... 

G. M. Yenwo, J. A. Manson, J. Pulido, L. H. Sperling, A. Conde, and N. Devia, Castor Oil Based Interpenetrating Polymer Networks, Synthesis and Characterization, J. Appi Polym. ScL 21(6), 1531 (1977). Castor oil-urethane/PS sequential IPNs. Physical properties. 

The first publieations related to synthesis and eharaeterization of polycyanurate-polyurethane full IPNs have appeared in 2000 [48]. Full sequential interpenetrating polymer networks (seq-lPNs) of eross-linked polyurethane (CPU) and polycyanurate (PCN) based on... 

An interpenetrating polymer network (IPN) is defined as a combination of two crosslinked polymers, at least one of which has been synthesised [98] and/or crosslinked in the immediate presence of the other. From the topological point of view, IPNs are closely related to pol)nner blends and to block, graft and crosslinked copolymers. From the synthesis point of view, IPNs can be classified, broadly, into two general types (a) sequential IPNs where a polymer network is formed which is then swollen by the monomer, plus a crosslinking agent and an activator, which is then polymerised in situ to form the second network and (b) simultaneous IPNs (SIPN) where the components necessary to form both networks are mixed and polymerised, at the same time, by non-competing mechanisms. If one of the two polymers is linear (uncrosslinked), a semi-IPN results. A homo-IPN results if both the network polymers are identical in chemical composition [98]. 

This indicates a simultaneous interpenetrating network, where Cn was formed by one reaction (say, addition), C22 was formed independently by another reaction (say, condensation), and the two networks are simultaneously polymerized. Without brackets a sequential synthesis of an interpenetrating polymer network is indicated ... 

IPN interpenetrating polymer network, the general term. Also used to indicate the time-sequential synthesis product. 

L. H. Sperling and D. W. Friedman, Synthesis and Mechanical Behavior of Interpenetrating Polymer Networks Poly(ethyl acrylate) and Polystyrene, J. Polym. Sci. A-2 7, 425 (1969). Synthesis of sequential IPNs. Modulus-temperature behavior. Modulus-composition behavior. 

G. M. Yenwo, Synthesis, characterization, and Behavior of Interpenetrating Polymer Networks and Solution Graft Copolymers Based on Castor Oil and Polystyrene, Diss. Abstr. Int. B 37(11), 5788, (1977). Castor oil-urethane/PS sequential IPNs. Synthesis, morphology, glass transitions, mechanical properties. Ph.D. thesis. 

An interpenetrating polymer network, IPN, is defined as a combination of two polymers, both of which are crosslinked. Most IPN s are formed by synthesizing and/or crosslinking one network in the immediate presence of the other. Formed with covalent crosslinks, IPN s are thermoset, and do not flow or dissolve in ordinary solvents. Two main synthesis paths are illustrated in Figure 1 (a) polymer network I is synthesized, and monomer II plus crosslinker and activator are swollen in and polymerized in situ. This is called a sequential IPN (b) if both monomers or prepolymers are synthesized simultaneously by independent but non-interfering routes, the product is called a simultaneous interpenetrating network, SIN. ... 

The synthesis of an IPN is illustrated in Figure 1, which shows both types of interpenetrating polymer syntheses. First, the reaction for a sequential IPN is shown, where monomer I is polymerized together with crosslinker I to produce a network. Then monomer II and crosslinker II are swollen in and polymerized in a sequential mode to make the IPN. 

Over the years, people have discovered many different ways of synthesizing IFN s. Figure 2 Illustrates the sequential IPN synthesis, top, and the simultaneous Interpenetrating network, SIN, synthesis, bottom. In the sequential synthesis, polymer network I Is swollen with monomer II plus crosslinker and activator, and polymerized In situ. The SIN synthesis begins with a mutual solution of both monomers or prepolymers and their respective crosslinkers, which are then polymerized simultaneously by noninterfering modes, such as stepwise and chain polymerizations. These methods have been used In the bulk, suspension, and latex states. Each will yield a distinguishable composition, even for the same polymer pair. 

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. 

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