Ionic liquid 1-butyl-3-methylimidazolium chloride (bmimCl) and its water mixtures were subjected to the temperature of −25 °C for various periods of time and then investigated by Raman and FTIR spectroscopy and WAXS. Neat bmimCl crystallized in a monoclinic lattice denoted M0. During a phase separation in samples with water concentrations of 0.44 and 2.90 wt %, a metastable monoclinic form denoted M was detected that was later converted into the monoclinic form M0 (0.44 wt %) or into an orthorhombic form (2.90 wt %). The form M existed only due to stresses imposed by hydrodynamic phenomena during the phase separation. According to Raman spectroscopy, the conformation of the butyl group in the bmim cation was identified as gauche–anti for the form M0 and as anti–anti for the orthorhombic form. Capillary forces and H-bonding affected the resultant conformation after the liquid–solid and solid–solid transitions. The ATR FTIR spectra in combination with DFT calculations unveiled further changes in the strength of hydrogen bonds between anion, cation, and water.

A comparative study of thermal response of poly(vinyl methyl ether) in the presence of different hydrophilic and hydrophobic additives was performed by Nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and optical microscopy. The effect of polymer concentration and additive content on the appearance and extent of the phase transition was determined. A detailed study of interaction mechanism in solutions with two hydrophobic additives showed differences in the way in which polymer globules are formed. For solutions containing t-butyl methyl ketone and t-butanol, measurements of ¹H spin-spin relaxations showed the presence of water and additive molecules bound in PVME globular structures. These originally-bound molecules are then slowly released from the globular-like structures. Incorporation of molecules into the globules disrupts the cooperativity of the transition and affects the size of globular structures.