Hyperbranched materials polymer characterization

The hydroxyfunctional hyperbranched polyesters have been characterized with respect to their mechanical and theological properties, both as thermoplastics and in cross-linked networks. The high number of terminal groups in hyperbranched polymers has a large impact on the properties, and also makes it easy to functionalize the polymers for various applications. One option is to attach reactive groups at chain ends, forming a cross-linkable polymer. Variations in functionality and the type of functional groups will affect both the polymer properties and the final cross-linked material properties. 

Dendritic macromolecules exhibit compact globular structures which lead to their low viscosity in the melt or in solution. Furthermore, dendritic macromolecules are characterized by a very large number of available functional groups, which lead to unprecedented freedom for changing/tuning/tailoring the properties of these multivalent scaffolds via complete or partial derivatization with other chemical moieties. All these features have contributed to multidisciplinary applications of these unique macromolecular structures in recent years 6, 7). The development of efficient synthetic routes in recent years has given rise to a virtually unlimited supply of commercially available dendritic polymers, at very affordable price. The transport properties of hyperbranched and dendritic polymers have recently attracted attention as potentially new barrier and membrane materials 8-9). 

B. Voit, H. Komber and A. Lederer, Hyperbranched Polymers Synthesis and Characterization Aspects. Materials Science and Technology, 2012, Wiley-VCH, Weinheim (Germany), p. 701. 

Unfortunately, none of the hyperbranched polymers smdied to date has demonstrated good mechanical properties. A hyperbranched PC is also expected to be a brittle material, but such a stmcture may prove interesting as a highly functionalized prepolymer for composites, coatings, and other applications. Hyperbranched PCs were synthesized and characterized by Bolton and Wooley. ° The products were prepared by the polymerization of an A2B monomer derived from l,Ll- nT(4 -hydroxyphenyl)-ethane. Silylation of the phenol terminated material with rert-butyldimethylsilyl chloride, followed by degradation of the carbonate hnkages by reaction with lithium aluminum hydride and analysis of the products by HPLC... 

Marija Pergal, MSc, works at the Department for Polymeric Materials, Institute for Chemistry, Technology and Metallurgy since 2003 as Research Scientist. Since 2007 she is also Teaching Assistant for the course Chemistry of Macromolecules at Department of Chemistry, University of Belgrade. Her research interests are focused on synthesis and characterization of siloxane homopolymers and copolymers, especially thermoplastic elastomers based on poly(butylene terephthalate) and polyurethanes, as well as polyurethane networks based on hyperbranched polyester. In addition to physico-chemical, mechanical and surface properties of polymers, her particular interest is directed towards the study of biocompatibility of polymer materials. 

The application of IGC to studies of polymeric systems was initiated in 1969 by Smidsrod and Guillet [9], who showed that gas chromatography could be used to demonstrate several interesting properties of the polymer. Nowadays, IGC is a useful and quite versatile technique for material characterization, because it can provide information on thermodynamic properties over a wide temperature range. To date, IGC has been used for the characterization of polymer blends [10], block copolymers [11,12], hyperbranched polymers [13[, fillers [14], and other materials [15-17]. 

In this chapter we consider the properties of synthetic polymers. First, the main techniques of polymer synthesis are outlined (Section 2.2). Then the conformation of polymer molecules is discussed in Section 2.3. We move on to a summary of the main methods for characterization of polymeric materials in Section 2.4. Then the distinct features of the main classes of polymer are considered, i.e. solutions (Section 2.5), melts (and glasses) (Section 2.6) and crystals (Section 2.7). Then the important properties of plastics (Section 2.8), rubber (Section 2.9) and polymer fibres (Section 2.10) are related to microscopic structure and to rheology. Polymer blends and block copolymers form varied structures due to phase separation, and this is compared and contrasted for the two types of system in Section 2.11. Section 2.12 is concerned with dendrimers and hyperbranched polymers. Section 2.13 and 2.14 deal with polyelectrolytes and (opto)electronic polymers respectively. 

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