Condensation polymers resources

Since the plastics are produced from petrochemicals derived from hydrocarbons, the motivation to reuse, recycle, or reprocess for energy recovery is primarily driven by an interest in conservation of petroleum resources. Economic factors are also important, but the potential saving of landfill space is more a perception rather than a reality [9]. Most of the categories of vinylic polymers discussed in this chapter are melt-formable, that is, they are thermoplastic materials, rather than nonmelting or thermosetting as are several of the condensation polymers discussed in Chapters 20 and 21. Thus,... 

This suggests that future research is in the direction of condensation polymers and modified natural polymers, especially starch as a very cheap and widely available natural resource. The research will require close attention to cost-performance characteristics to develop competitive products since current nonbiodegradable products are not apparently creating environmental problems, though there is a nagging doubt since all the evidence is based on the absence of negative responses to date. 

Keefer, K. D., Structure and Growth of Silica Condensation Polymers. In Silicon-Based Polymer Science. A Comprehensive Resource, Zeigler, J. M. Fearon,... 

Based on current standard testing methods and specifications, several renewable resource polymers may be considered biodegradable, the foremost being starch blends, cellulosic derivatives, polyhydroxyalkanoates and poly(lactic acid). Several new and old condensation polymers based on monomers obtained from fossil resources, such as polycaprolactone and the Bionolle series from Japan (Showa High Polymers) based on suucinic acid, are also acceptable by current standards, as are there blends with natural polymers such as starch. 

Despite the condensed format of this overview, I hope that it manages to convince readers that the interest in monomers from renewable resources is not a passing whim of some polymer chemists led astray by fashionable trends, but, instead, a very sound strategy that should help to shape the future of polymer science and technology. Although obviously not all these studies will reach viable practical realizations in terms of novel macromolecular materials, it is indispensable to build a rich database in preparation for the progressive dwindling of fossil... 

Hyperbranched polymers also possess a dendritic architecture, but with imperfect branching. The basic structural features present in these molecules are the same as in dendrimers, namely, a core surrounded by layers of BC capped with terminal units. The one-pot syntheses used to create these treelike stmctures also rely upon AB -type monomers (Scheme 30.1), but without protecting groups preventing simultaneous condensation reactions. The resulting polymers typically have broad MWD ( ) > 2), with multiple isomers and geometries. Because they are created in a single reaction step, hyperbranched polymers are more economical to produce than dendrimers as their synthesis is less time and resource intensive. This trait represents a major draw for industry and the development of commercial applications for dendritic polymers... 

Poly(ether-ester)s have been prepared by condensation of adipoyl or terephthaloyl chloride with an isosorbide-based ether-diol (Scheme 3.10). The parent isosorbide is obtained from renewable resources, hydrogenation, and subsequent dehydration of D-glucose. The polymerizations were accelerated about five times under microwave heating using a scientific microwave unit as compared to conventional methods, and a 95% yield of the desired polymers was obtained within 5 min at 180 °C. 

Bio-based materials are receiving wide attention, in consequence innovative technologies and competitive industrial products are reducing the dependence on petrochemicals for the production of polymers. Increasing concerns about the environmental degradation caused by conventional polymers have directed worldwide research toward renewable resources. Natural polymers are one of the readily available alternatives for the synthesis path of polyurethanes. The functional groups present in this kind of polymer can be activated for condensation polymerizations, and polyurethane is produced by this route. The incorporation of moieties from natural polymers into the synthetic polymer chain allows tailoring of the properties of polyurethane products for widespread application. 

This condensed survey of how furan monomers and furan chemistry can benefit polymer science hopefully provides two major reflections. The first has to do with the fact that it is possible in principle to build a comprehensive new family of macromolecular materials in which some, if not all, of the precursors are derived from renewable resources. In other words, there is no intrinsic limit to the variety of furan monomers that can be synthesized from F, HMF and their homologues and hence no limit to the polymers and copolymers that they can generate. This constitutes an encouraging potential in terms of the possibility of gradually replacing fossil-derived monomers and polymers by this alternative family. 

Other grafts to natural materials are exemplified by Dordick s work [173] in which he produced polyesters from sugars and polycarboxylates by enzyme catalysis of the condensation polymerization. These polymers and the method of synthesis may well be the future of renewable resource chemistry. 

Based on this lactide intermediate method. Nature Works LLC has developed a patented, low cost continuous process for the production of lactic acid-based polymers. The process combines the substantial environmental and economic benefits of synthesizing both lactide and PLA in the melt rather than in solution and, for the first time, provides a commercially viable compostable commodity polymer made from annually renewable resources. The process starts with a continuous condensation reaction of aqueous lactic acid to produce low molecular weight PLA pre-polymer (Fig. 6.5). 

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