Morphology Multicomponent polymers, types

Most, but not aU, of the multicomponent polymer combinations exhibit some type of phase separation, as is discussed in Chapters 4 and 13. Where the polymers are stainable and observable under the electron microscope, characteristic morphologies are often manifest. The principal polymers that are... 

To increase our understanding of the surface morphology of multicomponent polymer systems, techniques are needed that provide two distinct types of information, namely spatial resolution on various length scales within the surface layer and sufficient depth resolution so that one can observe the transition from surface to bulk structure in the material. When the domain sizes are on the order of micrometres, they should be visible by optical microscopy. 

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. 

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