Backbone structure step-growth polymers

The dependence of polymer properties on chemical compositions is reviewed in basic polymer texts.9,10 The backbone structure of a polymer defines to a large extent the flexibility and stability of a polymer molecule. Consequently, a great range of polymer properties can be achieved within each class of step-growth polymers by varying the backbone structure using different monomers. 

A different approach of modeling ethylene-based copolymers is presented using acyclic diene metathesis (ADMEl) polymerization. Monomer s)mtiiesis dictates final polymer structure due to step-growth chemistry yielding only to olefin metathesis. While copolymerization of ethylene with a-olefins produces random distribution of alkyl branches along the PE backbone, polymerization of one kind of symmetric macromonomer produces PE with a perfectly known primary structure, as seen in Figure 1. 

Find the chemical structures of sebacic acid and propylene glycol (use your textbook, a chemistry handbook, or the Internet). Will these react by free radical (addition) polymerization or condensation (step growth) polymerization Write the order of the atoms along the repeat unit on the polymer backbone (do not include pendant groups or groups foimd only at the end of the polymer chain). 

Lee and Jin (2003) were the first to report the growth of metallic NPs inside a thermotropic LC based on polymeric materials. A polyester matrix polymer consisting of hydrophilic PEG branches attached to a hydrophobic aromatic polyester backbone was used for his purpose (see Table 21.1 and Fig. 21.8a). This structure tended to be organized in smectic-like domains with the PEG branches occupying the inter-layer domains. Gold nanoparticles were obtained in a two-step procedure. First an aqueous solution of HAuCU was allowed to diffuse into the hydrophilic domains. Then, these gold ions were reduced to Au NPs upon addition of a hydrazine solution as shown on TEM micrographs in Fig. 21.8b. The mesomorphous properties of the LC/NP hybrid were not discussed. 

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