ma8b02594_si_001.pdf (1.65 MB)
Crystal Polymorphism of Biobased Polyester Composed of Isomannide and Succinic Acid
journal contribution
posted on 2019-06-12, 20:13 authored by Hironori Marubayashi, Takaaki Ushio, Shuichi NojimaThe
crystallization and solid-state structure of the biobased polyester
composed of isomannide and succinic acid (M4) were systematically
investigated by changing the crystallization conditions such as casting
solvent and crystallization temperature (Tc). It was found from wide-angle X-ray diffraction that M4 had the
crystal polymorphism: casting from the chloroform solution gave the
α-form, whereas thermal annealing at Tc ≥ 160 °C gave the β-form. A mixture of
α- and β-forms was obtained at Tc < 160 °C, and the β-form fraction increased
with increasing Tc. The unit cell of the
α-form was determined by the fiber diffraction method: a = 0.523 nm, b = 0.913 nm, c (fiber axis) = 2.082 nm, and α = β = γ = 90°
(monoclinic P21), where two 2/1 helices
were packed in the unit cell in a parallel manner. M4 chains in the
β-form took the same chain conformation but a different chain
packing. The crystallization half-time of M4 drew an inverted bell-shaped
curve against Tc, in which the minimum
was ca. 200 s at Tc = 140–150 °C.