Interpenetrating polymer networks formation

G. C. Berry and M. Dror, Modification of Polyurethanes by Interpenetrating Polymer Network Formation with Hydrogels, Am. Chem. Soc. Div. Org. Coat. Plast. Chem. Pap. 38(1), 465 (1978). Polyether-urethane-urea block copolymers with crosslinked HEMA, NVP, or acrylamide. IPNs and gradient IPNs for biomedical purposes. Strength, water swellability, and good blood compatibility. 

Brovko 0 0, Fainleib A M, Slinchenko E A, Dubkova V I and Sergeeva L M (2001) Filled semi-interpenetrating polymer networks formation kinetics and properties. Compos Polym Mat 23(2) 85-91. 

Hyperbranched polyurethanes are constmcted using phenol-blocked trifunctional monomers in combination with 4-methylbenzyl alcohol for end capping (11). Polyurethane interpenetrating polymer networks (IPNs) are mixtures of two cross-linked polymer networks, prepared by latex blending, sequential polymerization, or simultaneous polymerization. IPNs have improved mechanical properties, as weU as thermal stabiHties, compared to the single cross-linked polymers. In pseudo-IPNs, only one of the involved polymers is cross-linked. Numerous polymers are involved in the formation of polyurethane-derived IPNs (12). 

Frisch, H. L. Du, Y. Schultz, M. Interpenetrating Polymer Network (IPN) Materials. In Polymer Networks. Principles of Their Formation Structure and Properties-, Stepto, R. F. T., Ed. Blackie Academic London, 1998 pp 186-214. 

Formation of industrially usable interpenetrating polymer networks derived from caster oil is described in Chapter 27. Products can vary from soft and flexible to hard and tough. 

Since the start of modern interpenetrating polymer network (IPN) research in the late sixties, the features of their two-phased morphologies, such as the size, shape, and dual phase continuity have been a central subject. Research in the 1970 s focused on the effect of chemical and physical properties on the morphology, as well as the development of new synthetic techniques. More recently, studies on the detailed processes of domain formation with the aid of new neutron scattering techniques and phase diagram concepts has attracted much attention. The best evidence points to the development first of domains via a nucleation and growth mechanism, followed by a modified spinodal decomposition mechanism. This paper will review recent morphological studies on IPN s and related materials. 

A substantial number of definitions in the terminology section are either of physical quantities or are expressed mathematically. In such cases, there are recommended symbols for the quantities and, when appropriate, corresponding SI units. Other terms have eommon abbreviations. The following format is used to indicate these essential eharaeteristics name of term (abbreviation), symbol, SI unit unit. Typical examples are tensile stress, interpenetrating polymer network (IPN). If there are any, alternative names or synonyms follow on the next line, and the definition on the sueeeeding lines. 

Note 2 Semi-interpenetrating polymer networks may be further described by the process by which they are synthesized. When an SIPN is prepared by a process in which the second component polymer is formed or incorporated following the completion of formation of the first component polymer, the SIPN may be referred to as a sequential SIPN. When an SIPN is prepared by a process in which both component polymers are formed concurrently, the SIPN may be referred to as a simultaneous SIPN. (This note has been changed from that which appears in ref [4] to allow for the possibility that a linear or branched polymer may be incorporated into a network by means other than polymerization, e.g., by swelling of the network and subsequent diffusion of the linear or branched chain into the network.). 

Interpenetrating polymer network prepared by a process in which the second component network is formed following the formation of the first component network. 

The examples summarized above are but indicative of the increasing body of evidence in support of the chemical bonding theory, and of the role of the silane organofunctional group in the formation of covalent bonds at the coupling agent/ matrix interphase by reaction or by co-polymerization with the formation of an interpenetrating polymer network. 

He XW et al. (1989) Poly(dimethylsiloxane)/poly(methyl methacrylate) interpenetrating polymer networks 1. Efficiency of stannous octoate as catalyst in the formation of poly(dimethylsiloxane) networks in methyl methacrylate. Polymer 30(2) 364-368... 

Zhou P, Xu Q, Frisch HL (1994) Kinetics of simultaneous interpenetrating polymer networks of poly(dimethylsiloxane-urethane)/poly(methyl methacrylate) formation and studies of their phase morphology. Macromolecules 27(4) 938-946... 

Abstract This article summarizes a large amount of work carried out in our laboratory on polysiloxane based Interpenetrating Polymer Networks (IPNs). First, a polydimethylsiloxane (PDMS) network has been combined with a cellulose acetate butyrate (CAB) network in order to improve its mechanical properties. Second, a PDMS network was combined with a fluorinated polymer network. Thanks to a perfect control of the respective rates of formation of each network it has been possible to avoid polymer phase separation during the IPN synthesis. Physicochemical analyses of these materials led to classify them as true IPNs according to Sperling s definition. In addition, synergy of the mechanical properties, on the one hand, and of the surface properties, on the other hand, was displayed. 

Fichet O, Vidal F, Laskar J, Teyssie D. (2005) Polysiloxane - Cellulose Acetate Butyrate Interpenetrating Polymer Networks - Synthesis and kinetic formation study. Part 1. Polymer 46 37 7... 

In order achieve the demands of expanded applications, new additives for surface modifications were developed. These additives are often fluoro compounds [13], sometimes fluoroalkylsilanes [14], and in many cases alkylsilanes. When these additives are incorporated into a polymer matrix, the extremely valuable properties of these chemicals like chemical inertness, thermo-oxidative stability, and resistance against water can be transferred to the whole polymer system. This incorporation can either be achieved by chemical bonding to the resin matrix or by formation of an interpenetrating polymer network. 

There are at least four general types of combinations of crosslinked (x) and linear (1) polymers in a two-component system both components crosslinked (xx), one or the other component crosslinked (lx or xl), and both components linear (11). Where at least one of the components has been polymerized in the presence of the other, the xx forms have often been called interpenetrating polymer networks (IPN), the lx and the xl forms termed "semi-IPNs", and the last, linear or in situ blends. There are also a number of ways in which the components can be formed and assembled into a multicomponent system. Sequential IPNs are prepared by swelling one network polymer with the precursors of the second and polymerizing. Simultaneous IPNs are formed from a mixture of the precursors of both components polymerization to form each component by independent reactions is carried out in the presence of the other precursors or products. Usually, the simultaneous IPNs that have been reported are extremes in the component formation sequence the first component is formed before the second polymerization is begun. Sequential IPNs and simultaneous IPNs of the same composition do not necessarily have the same morphology and properties. 

In this regard, preferential use of NIPU in hybrid systems based on copolymerization and modification of other polymer materials seems promising. Using an interpenetrating polymer network (IPN) principle in production of composite materials provides a unique possibility to regulate their both micro- and nanostructures and properties. By changing the IPN formation conditions (sequence of polymerization processes, ratio of components, temperature, pressure, catalyst content, introduction of filler, ionic group, etc.), it is possible to obtain a material with desirable properties. 

From the conversion dependence of the insolubilization process, it was concluded that both inter- and intramolecular propagation reactions occur during the polymerization of the epoxy ring. Blends of epoxidized polyisoprene and difunctional vinyl ether or aciylate monomers were shown to undergo a fast and extensive cross-linking polymerization, with formation of interpenetrating polymer networks. 

The major problem with immiscible blends is the poor physical attraction at phase boundaries that can lead to phase separation under stress resulting in poor mechanical properties. A number of ingenious approaches have been adopted to overcome this problem by improving compatibility between immiscible phases. One is through formation of interpenetrating polymer networks (IPN) as described in Table 4.34. 

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