Interpenetrating polymer network definition

IPNs are found in many applications though this is not always recognised. For example conventional crosslinked polyester resins, where the polyester is unsaturated and crosslinks are formed by copolymerisation with styrene, is a material which falls within the definition of an interpenetrating polymer network. Experimental polymers for use as surface coatings have also been prepared from IPNs, such as epoxy-urethane-acrylic networks, and have been found to have promising properties. 

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. 

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. 

In its broadest definition, an interpenetrating polymer network, IPN, is any material containing two polymers, each in network form/" A practical restriction requires that the two polymers have been synthesized and/or crosslinked in the immediate presence of each other. Two types of IPNs are illustrated in Figure The sequential IPN begins with the... 

The above represents the classical definition of an IPN. The term interpenetrating polymer network was coined before the extent or conseqnences of phase separation were fully realized. This article covers sequential and simultaneous types of IPNs made in bulk and also includes such materials as IPNs based on latexes and suspension-sized particles thermoplastic IPNs, which contain physical cross-links in one or both polymers, and hence may be (partly) soluble and a number of other closely related materials. 

Multicomponent polymeric materials consist of polymer blends, composites, or combinations of both. A polymer blend has two definitions The broad definition includes any finely divided combination of two or more polymers. The narrow definition specifies that there be no chemical bonding between the various polymers making up the blend. Table 2.5 and Section 2.7 summarize the basic types of polymer blends based on the broad definition primarily these are the block, graft, star, starblock, and AB-cross-linked copolymers (conterminously grafted copolymers), interpenetrating polymer networks, as well as the narrow definition of polymer blends. More complex arrangements of polymer chains in space can be shown to be combinations of these several topologies. 

AB crosslinked polymers, ABCP s, and interpenetrating polymer networks, IPN s, more precise definitions of crosslinks became required. While AB crosslinked polymers are listed in Table I, graft and block copolymer bonds per se are not included because these materials remain soluble (uncrossiinked) in the simple case. 

A term sometimes used to mean interpenetrating polymer networks A definite part of a system, homogeneous throughout and physically separated from other phases by distinct boundaries. 

Latex IPNs, by definition, have their origin in emulsion polymerization. Several types of latex IPNs exist. If one blends two kinds of latex particles, followed by film formation and cross-linking of both polymers, the material is called an interpenetrating elastomeric network, TEN. Usually, lENs form a three-dimensional mosaic structure (69,70). 

Although this definition still fits most materials called IPNs, now some hybrid polymer blends, such as thermoplastie ayyarent IPNs, call for a broader concept [3,7,8]. In contrast to the chemically crosslinked IPNs, physical bonds are characteristic of the crosslinking in thermoplastic apparent IPNs. These physical bonds are glassy domains of block copolymers, ionic clusters in iono-mers, or crystalline domains in semicrystalline polymers. The components of thermoplastic IPNs are capable to form physical networks and are characterized by interpenetration of phases. Thermoplastic apparent IPNs take an inter-... 

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