Vibrational and structural properties of amorphous n-butanol: A complementary Raman spectroscopy and X-ray diffraction study

Abstract

Raman spectroscopy and X-ray diffraction experiments were performed in the liquid, undercooled liquid, and glassy states of n-butanol. Clear correlated signatures are obtained below the melting temperature, from both temperature dependences of the low-wavenumber vibrational excitations and the intermediate-range order characterized by a prepeak detected in the different amorphous states. It was found that these features are related to molecular associations via strong hydrogen bonds, which preferentially develop at low temperature, and which are not compatible with the long-range order of the crystal. This study provides information on structural heterogeneities developing in hydrogen-bonded liquids, associated to the undercooled regime and the inherent glass transition. The analysis of the isothermal abortive crystallization, 2 K above the glass transition temperature, has given the opportunity to analyze the early stages of the crystallization and to describe the origin of the frustration responsible for an uncompleted crystallization.

Temperature-dependent self-assembly and rheological behavior of a thermoreversible pmma-PnBA-PMMA triblock copolymer gel

“…For n ‐butanol [Fig. (a)], during cooling several small exothermic peaks have been observed related to the crystallization of n ‐butanol . The exothermic peak at about −110 °C during heating is attributed to the cold crystallization process, and an endothermic peak at approximately −90 °C represents the melting of the crystals.…”

A systematic study of the isothermal crystallization of the mono-alcohol n-butanol monitored by dielectric spectroscopy

“…Based on the dielectric spectra presented here it is perhaps difficult to distinguish between the two scenarios, but the fact that the structural relaxation peaks disappear entirely combined with the emergence of Bragg peaks as documented in Ref. [21], point to a non-trivial crystallization process as the most obvious explanation for the observations.…”

“…Thus we confirm earlier findings that the crystallization process at temperatures near T g stops before the sample is completely crystallized. Hedoux et al report signs of an aborted or frustrated crystallization process, signaled by a amorphous halo persisting in the x-ray spectra [21]. This slow and frustrated crystallization process has also been interpreted as a polyamorph transformation between two meta-stable liquid phases [24,[33][34][35].…”

“…It also exhibits a slow crystallization process upon reheating after a rapid quench below T g [19,20]. At 10 K above the glass transition temperature the crystallization can take several days to finish, and at temperatures close to the glass-transition, the crystallization process stops before the sample is fully crystallized [21]. These two properties, a large dielectric signal and slow crystallization, makes n-butanol an ideal candidate for monitoring isothermal crystallization in real time by dielectric spectroscopy.…”

“…These two properties, a large dielectric signal and slow crystallization, makes n-butanol an ideal candidate for monitoring isothermal crystallization in real time by dielectric spectroscopy. Crystallization of n-butanol has previously been studied with x-ray diffraction [19,20], infrared spectroscopy [21,22], calorimetric methods [23], and phase contrast microscopy [24]. However, no systematic study of the temperature dependence and reproducibility of the crystallization kinetics has been reported.…”