Epimerized isotactic polystyrene

Our previous reports concerned 20 MHz 13C-NMR spectra of partially epimerized polystyrenes. The aromatic C-l carbon resonances were recorded at room temperature and were poorly defined when the extent of epimerization was high. A need for remeasuring these resonances at higher temperature, using higher field spectrometers was clearly evident. This paper is therefore concerned with the 75 MHz 13C-NMR specrra of partially epimerized isotactic polystyrenes. 

HARWOOD ETAL. Polystyrene and Epimerized Isotactic Polystyrenes 201... 

Aromatic C-l Resonance. Figures 1-6 show aromatic C-l carbon resonance patterns observed for various epimerized isotactic polystyrene samples. The patterns are easily divided into six resonance areas, that are designated A-F in order of increasing field. Areas A, C and E are clear in these Figures while areas B, D and F are cross-hatched. Except for the resonance pattern observed for atactic polystyrene (Figure 6), the resonances appear to be assignable as follows ... 

Carbon Resonance Pattern of an Epimerized Isotactic Polystyrene Sample Having a mm-Content of 0.70. 

Epimerized Isotactic Polystyrene Samples from Aromatic C—1 Carbon Resonances and Calculated by Monte Carlo Simulation... 

Table IV. Heptad Stereosequences Responsible for Minor Signals in Partially Epimerized Isotactic Polystyrene Samples having mm-Contents Below 0.50.

Although the aromatic C-l carbon resonance of polystyrene is very complex, relatively simple aromatic C-l carbon resonance spectra are observed for partially epimerized isotactic polystyrenes. Studies on such "model polystyrenes" provide the information needed to interpret the spectrum of polystyrene itself. Based on assign-... 

Table III. Correlation of A-F Aromatic C-1 Carbon Resonance Areas Measured for Polystyrene and Epimerized Isotactic Polystyrene Samples with Stereosequence Distributions Calculated by Monte Carlo Simulation (V=0.65)...

---