7.2 HR-MAS of swollen polymers

 

Some polymers are nearly insoluble and as a result, obtaining high resolution NMR spectra may become impossible. An example is a range of poly acethylene derived polymers. These samples show an extremely low solubility in most common solvents and attempts to obtain solution spectra result in low signal to noise ratios and long measurement times. Solid state spectra, on the other hand, can be obtained but generally display a poor resolution.

 

A solution to this dilemma is to swell the polymer with a solvent and to acquire spectra while spinning at the magic angle. Figure 7.7 displays proton and carbon spectra of a derivative of poly acethylene, swollen in chloroform. The carbon spectrum was obtained in about two hours.
 

Figure 7.7. 500 MHz proton (top) and carbon (bottom) spectra of a derivative of poly acethylene, swollen in deuterated chloroform.