An infra-red study of model compounds of poly(tetramethylene terephthalate)

An infra-red spectroscopic investigation of the poly(tetramethylene terephthalate) model compounds butyl-dibenzoate: C₆H₅COO(CH₂)₄OCOC₆H₅ (i), 1,4-bis-butyl terephthalate: HO(CH₂)₄-OCO₆H₄COO(CH₂)₄-OH (ii), α-butyl-ω-butoxyterephthalaoyl-di-(tetramethylene terephthalate): H(CH₂)₄(OCOC₆H₄COO-(CH₂)₄-)₃-OH (iii), and α-butyl-ω-butoxyterephthalaoyl-tetra-(tetra-methylene terephthalate): HO(CH₂)₄-(OCOC₆H₄COO(CH₂)₄-)₅-OH (iv) is presented. The synthesis of (i) is also described. Spectroscopic evidence indicates that the crystal conformations of the aliphatic segments in (i) and (ii) closely resemble the extended all trans beta form of PTMT. Oligomers (iii) and (iv), however, are found to be more similar to the crumpled alpha crystal phase of PTMT.