Solid multifunctionality

Finally, it can be envisaged that the future development of novel bio-nanohybrids will lead to new improved properties and multifunctionality derived from the synergistic combination of nanosized inorganic solids, with different structural and textural features, with molecular or even highly organized species of biological origin that are extraordinarily abundant in Nature. 

In conclusion, there is interest for bioethanol upgrading to fuel additives and some research is active in this direction, but much more effort is needed to demonstrate the validity and the viability of the concept of preparing oxygenated diesel fuel additives from bioethanol and glycerol. The key to success is to develop selective multifunctional solid catalysts, in which interest is more general, because similar multifunctionality is necessary in the catalytic synthesis of fine chemicals [67]. There is, thus, the possibility of cross-fertilization between the two research areas. 

The multifunctionality contributes higher reactivity and cross-link density. These factors are especially critical when formulating systems that require improved thermal performance over conventional epichlorohydrin—bisphenol A systems. The melt viscosity of these resins, which are solids at room temperature, decreases sharply with increasing temperature. This affords the formula tor an excellent tool for controlling flow of molding compounds, and facilitating the incorporation of ECN resins into other epoxies, eg, for powder coatings. 

Epoxy novolac resins also differ from standard DGEBA-based epoxy resins in their multifunctionality, which is about 2.5 to 6.0. The multiplicity of epoxy groups allows these resins to achieve increased crosslink density. The commercial epoxy novolac resins (e.g., DER 438, Dow Plastics, and EPON 164, Resolution Performance Products LLC) are semisolid to solid resins with EEW in the range of 170 to 230. Recently low-viscosity epoxy novolac resins have been produced (18,000 to 28,000 cP) to provide easy processing however, these generally have lower epoxy content. 

Figure 2.66 Multifunctionality of solid catalysts synthesis of maleic anhydride from n-butane over a (V0)2P207 catalyst.

The magnitude of the achievements in the more quantitative, physical science of the Haber-Bosch program has tended to outshine the contributions from both the associated exploratory catalytic chemistry and the concepts derived therefrom. The work of Mittasch was absolutely vital and led ultimately to the development of the more effective catalysts which had commercial potential and to improved gas purification. As pointed out in this volume, some of those ideas have had to be abandoned, but it is inescapable that the notion of multifunctionality, implying jumpover, spillover, or switchover of intermediates, was contained therein, albeit formalized much later by Weiss and others. Indeed, phenomena at interfaces between solids remained unapproachable until the application of the latest physical techniques (Chapters 2-5). 

In this review we will discuss the multifunctional linkers in terms of assembly on solid supports, stability towards reaction conditions, and finally the issue of introduction of multifunctionality. 

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