Study of the Crystal Structure and Hydrogen Bonding during Cold Crystallization of Poly(trimethylene 2,5-furandicarboxylate)

Here, we present
a detailed description of the in situ isothermal
crystallization of poly(trimethylene 2,5-furandicarboxylate)(PTF)
as revealed by real-time Fourier transform infrared spectroscopy (FTIR)
and grazing incidence wide-angle X-ray scattering (GIWAXS). From FTIR
experiments, the evolution of hydrogen bonding with crystallization
time can be monitored in real time, while from GIWAXS, crystal formation
can be followed. Density functional theory (DFT) calculations have
been used to simulate FTIR spectra for different theoretical structures,
enabling a precise band assignment. In addition, based on DFT ab initio calculations, the influence of hydrogen bonding
on the evolution with crystallization time can be understood. Moreover,
from DFT calculations and comparison with both FTIR and GIWAXS experiments,
a crystalline structure of poly(trimethylene 2,5-furandicarboxylate)
is proposed. Our results demonstrate that hydrogen bonding is present
in both the crystalline and the amorphous phases and its rearrangement
can be considered as a significant driving force for crystallization
of poly(alkylene 2,5-furanoate)s.