NMR spectra of amorphous polymer

B. Bom, H. W. Spiess, Ah Initio Calculations of Conformational Effects on NMR Spectra of Amorphous Polymers Springer-Verlag, New York (1997). 

Ab Initio Calculations of Conformational Effects on C NMR Spectra of Amorphous Polymers... 

The linewidths of the high resolution scalar decoupled and NMR have been studied for semicrystalline P(4HB) and P(3HB-co-18%4HB) in the amorphous phase and in the melt as functions of temperature and magnetic field strength [87]. There are two classes of origins, which exert linebroadening of the NMR spectra of amorphous or semicrystalline polymers,... 

Figure 15 shows the Si and C CP/MAS NMR spectra of PMPhSM at room temperature. From the Si CP/MAS NMR spectrum, only one broad line is observed at —4.5 ppm. This polymer is an amorphous polymer so that this broad signal means a conformational distribution along the Si-C backbone. Peaks at 141.7 ppm (the Cl), 134.0 ppm (the C2), 128.5 ppm (the C3 and C4), 7.0 ppm (the methylene carbon) and 0.5 ppm (the methyl carbon) are observed in the C CP/MAS NMR spectrum. The broad signal is assigned to the methylene carbons of the main-chain implies conformational distribution along the Si-C backbone in a similar manner to the Si NMR... 

Figure 7. NMR spectra of an amorphous polymer at various temperatures,...

Oguni and co-workers have examined the carbon-13 NMR spectra of crystalline poly(propylene oxideD and of amorphous poly-(propylene oxideD made with a base catalyst (8 ). They made the peak assignments shown in Figure 5. The spectrum of the crystalline polymer contained three peaks at 17.33, 73.98, and 75.98 ppm. downfield from tetramethylsilane. These were identified as arising from methyl, methylene, and methine carbons, respectively. 

Fig. 17. Carbon 13 NMR spectra of the amorphous part of poly(methyl oxirane) obtained in stereoelective polymerization. Optical activity of the polymer = 6.3 (C H, C = 1).

Figure 1 NMR CRAMPS spectra of amorphous polystyrene (top) and crystalline adipic acid (bottom), showing different degrees of resolution. Reproduced with permission of Elsevier Science from Gerstein BC (1998) NMR. In Ando I and Asakura T (eds) Solid State NMR of Polymers, Vol 84, pp 166-189. Amsterdam Elsevier Science.

---