Polymer Synthesis and Processing

The use of RTILs in polymer synthesis and processing has significantly increased during the last decade and this has resulted in reviews and symposia dedicated to the topic.However, the field is less advanced than polymerizations in other green media such as water and SCCO2. Reactions that have 

Based on an understanding of how [Bmim]Cl was able to dissolve cellulose, which is generally insoluble in most common organic media, researchers have 

Another advance in this area has come in the degradation of lignocellulosic materials through hydrolysis using hydrochloric acid in an RTIL to afford 

The large macromolecules of the commercially useful polymers must be synthesized from substances having smaller molecules in a process termed polymerization. Furthermore, the properties of a polymer may be modified and enhanced by the inclusion of additive materials. Finally, a finished piece having a desired shape must be fashioned during a forming operation. This section treats polymerization processes and the various forms of additives, as well as specific forming procedures. 

Addition polymerization (sometimes called chain reaction polymerization) is a process by which monomer units are attached one at a time in chainUke fashion to form a linear macromolecule. The composition of the resultant product molecule is an exact multiple of that of the original reactant monomer. 

Three distinct stages—initiation, propagation, and termination—are involved in addition polymerization. During the initiation step, an active center capable of propagation is formed by a reaction between an initiator (or catalyst) species and the monomer unit. This process has already been demonstrated for polyethylene in Equation 14.1, which is repeated as follows  

Propagation involves the linear growth of the polymer chain by the sequential addition of monomer units to this active growing chain molecule. This may be represented, again for polyethylene, as follows  

Chain growth is relatively rapid the period required to grow a molecule consisting of, say, 1000 repeat units is on the order of 10 to 10 s. 

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Tager AA, Yushkova SM (1984) In Physical chemistry of polymer synthesis and processing, Univ. of Gorky press Gorky, p 52... 

Cooper, A.I. (2000) Polymer synthesis and processing using supercritical carbon dioxide. Journal of Materials Chemistry,... 

A variety of strategies for reducing or eliminating the use of traditional organic solvents in polymer synthesis and processing have been discussed recently [14]. 

Over the past decade, carbon dioxide has become an attractive alternate solvent for a variety of polymer synthesis and processing applications due to its environmentally benign nature and chemical inertness I T Properties of CO2, such as dielectric constant and density are sensitive to the temperature and pressure of the system. The fluid density and dielectric constant, can be fine tuned using temperature and pressure profiling. In addition, CO2 offers an environmentally sound medium with the potential to eliminate organic and aqueous waste streams in manufacturing facilities. 

Joseph M. DeSimone (BCST Liaison) is William R. Kenan, Jr., Distinguished Professor of Chemistry and Chemical Engineering at North Carolina State University and the University of North Carolina. He is also director of the National Science Foundation Science and Technology Center for Environmentally Responsible Solvents and Processes. He received his B.S. in chemistry form Ursinus College and his Ph.D. in chemistry from Virginia Polytechnic Institute and State University. His areas of interest include polymer synthesis in supercritical fluids, surfactant design for applications in interfacial chemistry, and polymer synthesis and processing—from fundamental aspects of chemical systems to the most efficient and environmentally friendly ways to manufacture polymers and polymer products. 

Listed below are some of the advantages of using a biocatalytic approach to polymer synthesis and processing. 

S.P.Zhiltsov and V.N.Kashaeva, in PhisicoGhemical Foundations of Polymer Synthesis and Processing, Gorkii, 1984. 

The oldest commercially used SCCO2 extraction process is the decaffeination of coffee beans. This is still the most profitable application of SCCO2, but supercritical fluids have been tested in the food industry, pharmaceutical industry, textile dyeing, impregnation, polymer synthesis and processing, dry cleaning, etc. ... 

With the introduction of oil-based polymers such as poly[ethylene], poly[propylene], poly[styrene], poly[ethylene terephthalate] and poly[vinyl chloride] the packaging industry has been truly revolutionised. Despite the advances in polymer synthesis and processing, their end of life still poses a problem [159]. The first choice for processing plastic waste is reuse, but only some plastics can be reused after proper processing, and... 

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