Conformation and packing of poly(alkylene phosphate) chains in the crystal lattice. Part II: Temperature FTIR studies

Abstract

The infra-red absorption of recrystallized samples of the polyhexa-, polyhepta-, polyocta-, polynona-, polydeca- and polydodecamethylenephosphate was measured during the heating, from the room temperature to the temperature higher than the melting temperature of the polymer examined. The heating induced changes of FTIR spectra proved, that the spatially arranged polyphosphate chains are cross-linked by the PO⋯H–O hydrogen bonds, whose properties consist with the properties of the theoretically predicted hydrogen bonds. Moreover, the strong crystal field splitting of the rocking vibrations of the polyphosphate monomer unit methylene chain and of the (P)– O–C stretching vibrations has been observed. As was founded, the dispersion curves of rocking vibrations of the polyphosphate chain (CH2)ntrans sequences may be approximated by the exponential function: ν=ν∞ exp (C/n). The crystal field splitting effects proved, that the unit cell of polyphosphate crystals contain two polyphosphate monomer unit, and that the conformation of the polyphosphate extended chains is close to the conformation of the modeled polyphosphate extended chains.