화학공학소재연구정보센터
Langmuir, Vol.24, No.2, 534-540, 2008
Thermal properties of the gel made by low molecular weight gelator 1,2-O-(1-ethylpropylidene)-alpha-D-glucofuranose with toluene and molecular dynamics of solvent
The studies of the gel-to-sol phase transition by the Raman, FT-IR, and H-1 NMR methods of the gel made by low molecular weight organogelator 1,2-O-(1-ethylpropylidene)-alpha-D-glucofuranose with toluene as the solvent are reported. The FT-IR spectra revealed the existence of a hydrogen bond network formed by gelator molecules in the crystalline and gel phase. In both phases, the network formation is dominated by the gelator self-interaction. Upon gelation, only one stretching band of infrared absorption modes v, assigned to the O(6)H hydroxyl protons of gelator, is shifted by Delta nu(alpha) = 25 cm(-1), which indicates the involvement of this proton in the interaction with the solvent molecules. The phase transition measurements performed as a function of gelator concentration allowed the calculation of the energy correlated with the transition front gel to solution phase. The obtained value of 72 kJ/mol is the largest one reported up until now for monosaccharide-based gels. The analysis of the temperature measurements of the toluene H-1 NMR spectra provides evidence for a different chemical environment of toluene molecules in the gel. The toluene spin-lattice relaxation in bulk and gel indicate that the viscosity is most likely the main factor that influences the dynamics of toluene.