Towards Larger Molecules From Oligomers to Polymers

5 Towards Larger Molecules From Oligomers to Polymers 

Molecular spectroscopy and lattice dynamics of oligomeric and polymeric materials have been treated thoroughly in several textbooks or articles [16-18]. We wish to point out here a few fundamental concepts which form the basis of the understanding of the spectra of disordered materials which will follow in this discussion. 

Let us first consider the vibrations of polymers considered as one-dimensional perfect and infinite lattices. The usual basic assumptions are the following  

The polymer is obtained by fonning a one-dimensional chain of chemical units linked with a pre-assigned chemical sequence. For sake of example, we consider propylene (CH3-CH=CH2) as the prototype of a monomer unit capable of producing a polypropylene chain. The first step is to make a chain of polypropylene in which all monomers are chemically linked head-to-tail [chemical 

During the polymerization process the catalysts is chosen in such a way that stereo-regidarity is assured [45], e.g., 

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