Thermodynamics Research Center / ThermoML | Thermochimica Acta

Effect of nanopore confinement on the thermal and structural properties of heneicosan

Deng, S.[Shuping], Wang, D.[Dongqing], Wang, X.[Xin], Wei, Y.[Yongteng], Waterhouse, G. I.N.[Geoffrey I.N.], Lan, X. Z.[Xiao Zheng]
Thermochim. Acta 2018, 664, 57-63
ABSTRACT
The effect of nano-confinement on the phase transitions of heneicosane (n-C21H44, C21) were investigated using differential scanning calorimetry (DSC) and variable temperature powder X-ray diffraction (XRD). When C21 is confined within the pores of controlled pore glasses (CPGs), SBA-15 or other mesoporous materials, the solid-solid (Ts) and solid-liquid (Tm) transition temperatures are depressed. The depression of the phase transition temperatures (ATs, ATm) for C21 in CPGs and SBA-15, the degree of supercooling and enthalpy change (AHs, AHm) for C21 in CPGs, exhibited a linear dependence on the inverse pore size. The ATm values were insensitive to the polarity pore wall but varied with the pore geometry. XRD analysis revealed that the lamellar ordering characteristic for the solid C21 was disturbed in the nanopores, with the extent increasing as the pore size decreased. A new rotator phase RII is found for C21 confined in CPG (12 nm) and SBA-15 (14.4 nm).
Compounds
# Formula Name
1 C21H44 heneicosane
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal 1
  • Crystal 1
  • Liquid
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 1
  • Crystal 1
  • Liquid
  • Air at 1 atmosphere
  • DSC
  • 1
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2
  • Crystal 2
  • Crystal 1
  • Air at 1 atmosphere
  • DSC
  • 1