Sequential distribution of main chain phosphorous-containing copolyesters characterized by H-1 NMR

Abstract

A series of main chain phosphorus-containing copolyesters were synthesized by polycondensation of terephthalic acid (TPA), ethylene glycol (EG) and phenyl phosphonic acid (PPA). Chemical structures of these main chain phosphorus-containing copolyesters were characterized by H-1 NMR. Experimental results show that the resonance intensity of PPA aromatic protons increases with increase of the phosphorus content. The chemical shifts of the ethylene protons in the ethylene glycol units vary with different sequences. The resonance chemical shift of the ethylene protons of the T-E-T unit is higher than those of P-E-T (T-E-P) and P-E-P units. The monomer molar fraction, sequential distribution and degree of randomness of the phosphorus-containing copolyesters were determined through analyses of the ethylene protons in the ethylene glycol units. The molar fractions of the PPA comonomer determined by H-1 NMR analyses are close to the values determined by a UV method. The degree of randomness for the copolyesters was found to be in the range 0.66-0.83. (C) 1998 SCI.