Studies on hexolic anhydride based polyesters, 1. characterization and sequence determination in hexolic based copolyesters by ¹H- and ¹³C-NMR

Abstract

The copolyesters and terpolyesters containing maleic or phthalic anhydride and 5,6,7,8,10,10-hexachloro-3a,4,4a,5,8,8a,9,9a-octahydro-5,8-methanonaphtho-[2,3-c]-furan-1,3-dione ('hexolic anhydride') with 2-butene-1,4-diol and 2,3-dichloro-2-butene-1,4-diol are synthesized by azeotropic condensation technique. The ¹H- and ¹³C-NMR spectra of these polyesters are recorded and the chemical shifts for the corresponding nuclear magnetic atoms are assigned. A good correlation exists between the observed and theoretically calculated chemical shift values. The sequence distribution, the randomness factor, and the number-average sequence length of each anhydride monomer unit are calculated using ¹H- and ¹³C-NMR spectra. It is found that both methods give identical results for the same copolyesters and terpolyesters. The results indicate that the copolyesters follow Bernoullian statistics and the terpolyesters correspond to alternative copolyesters.