Elastic properties of the RIV–RIII rotator phases of alkanes

Elasticity and phase behaviour of n-heptane and n-nonane in nanopores

“…We can compare these results for the intrinsic shear modulus of the confined heptane and nonane with the scanty values known for other alkanes from previous experimental or theoretical studies [1,[15][16][17][18][19]. Jiménez et al measured a shear modulus (C 44 ) of up to 0.5 GPa for the rotator phase of C 17 H 36 [19].…”

“…The R V orthorhombic rotator phase of pentacosane (C 25 H 52 ) is according to the same group smaller than 0.05 GPa [17], whereas theoretical calculations predict a modulus between ≈ 0.38 GPa and ≈ 0.45 GPa for the R V phase and a modulus of up to 0.3 GPa for the R I phase [16]. Differences in the elastic behaviour were also found between the rotator phases R III and R IV : The value for the modulus is up to ≈ 1.0 GPa for R III and only up to ≈ 0.2 GPa for R IV [15].…”

“…3) evidence that at high temperatures the alkanes in the pores possess a modulus in a range between G nonane pore ≈ 0.10 GPa and G heptane pore ≈ 0.25 GPa. This raises the question as to whether the nanoconfinement causes the formation of a rotator phase at high temperatures as the shear modulus of such phases cannot be zero [15].…”

“…refs. [1,[15][16][17][18][19]). The elastic properties of alkanes in nanoconfinement, however, were completely neglected and in this paper we present the first study, to our knowledge, on the elasticity of normal alkanes in nanopores.…”

Simple Landau Model of the Liquid-RII-RI Rotator Phases of Alkanes

“…The first approach consists of Monte Carlo and molecular dynamics simulations [16][17][18][19][20][21][22] which confirms the first order character of the Liquid-R II (IL-R II ) and R II -R I transitions. The second approach is pursued by Wurger [23] and Mukherjee [24][25][26][27][28][29][30][31][32][33][34]. Wurger [23] developed a microscopic model for the pair interaction of hydrocarbon chains and discussed the detailed structure of the R I and R II phases in terms of a molecular-field approximation.…”