Polymer compounds platform

The versatility of poly(phenylcne) chemistry can also be seen in that it constitutes a platform for the design of other conjugated polymers with aromatic building blocks. Thus, one can proceed from 1,4- to 1,3-, and 1,2-phenylene compounds, and the benzene block can also be replaced by other aromatic cores such as naphthalene or anthracene, helerocyclcs such as thiophene or pyridine as well as by their substituted or bridged derivatives. Conceptually, poly(pheny ene)s can also be regarded as the parent structure of a series of related polymers which arc obtained not by linking the phenylene units directly, but by incorporation of other conjugated, e.g. olefinic or acetylenic, moieties. 

Some other natural compounds have been transformed for their use in the synthesis of polymers via olefin metathesis processes. As mentioned in the introduction, furans, which are obtained from carbohydrates, are perfect precursors of monomers for ROMP via simple Diels-Alder cycloadditions (n) (Scheme 25) [26]. In this regard, the first example of the ROMP of 7-oxabicyclo[2.2.1]hept-5-ene derivatives was reported by Novak and Grubbs in 1988 using ruthenium- and osmium-based catalysts [186]. The number of examples of ROMP with monomers with this generic structure is vast, and it is out of the scope of this chapter to cover all of them. However, it is worth mentioning here the great potential of a renewable platform chemical like furan (and derived compounds), which gives access to such a variety of monomers. 

Genetic engineering of plants may be used for the production of novel polymers and basic chemicals. These methods may help to alleviate the demands for hmited resources and provide a platform to produce some desired compounds in bulk quantities. 

Xylitol is a specialty chemical with the effects of extreme cooling, caries prevention and safety for diabetes, which are beneficial for manufacturing foods and mouth-care products. As a platform chemical, it also can be converted to various compounds for polymer synthesis and directly polymerized for production of unsaturated polyester resin (Werpy and Petersen, 2004). Danisco (currently part of Dupont Co.) is the largest xylitol producer, and many companies in China and South America (Brazil) manufacture xylitol commercially. The global market of xylitol is estimated to be more than 125,000 tons per year, with 4.5-5.5/kg for bulk purchase and 20/kg in supermarket (da Silva and Chandel, 2012). Xylitol has a 12% share of the total polyols market with growth estimated to increase threefold (da Silva and Chandel, 2012). The xylitol market continues to increase worldwide due to an enhancement in health consciousness and chewing gum market, and new application development as a chemical feedstock. 

This chapter presents an overview of amorphous spray-dried dispersions (SDDs), which have been successfully used as a platform technology to enhance the oral bioavailability of hundreds of compounds with low aqueous solubility. SDDs can be prepared with several nonionic polymers, such as polyvinylpyrrolidone (PVP) and cellulosic polymers, as well as with ionic polymers, such as hydroxypropyl... 

---