Characterizing polymers with heterogeneous micro- And macrostructures

The potentially extreme heterogeneity of polymer micro- and macrostructures has been demonstrated and a means for characterizing them has been suggested. To ensure that all possible microstructures, such as diad stereosequences in vinyl homopolymers and monomer sequences in copolymers, including their locations along polymer chains, that is, all macrostructures, are represented, it became necessary to generate samples with huge quantities (many many tons) of constituent polymer chains. This suggested a practical need for distinguishing between polymer samples with chains that have homogeneous and heterogeneous populations of micro- and macrostructures. A combination of high resolution ¹³C-nuclear magnetic resonance to determine the types and amounts of constituent short-range microstructures, and dilute solution electrical birefringence or Kerr effect measurements to locate them along the polymer chains has been suggested, and may be able to achieve this distinction. This combination of techniques is required to reduce the innumerably large numbers of different possible polymer macrostructres whose Kerr constants would have to be calculated, for comparison to the observed values. The ability to determine polymer macrostructures is critical to the development of relevant, more meaningful, and therefore, improved structure-property relations for polymer materials.