Quantitative Simulations on Temperature-Dependent Lattice Thermal Capacity of Linear, Branched and Cyclic Polymers
Abstract
Valeri Ligatchev
Effects of spatial confinement, and interactions among neighboring molecular fragments, as well as amendments in topological characteristics are taken into account explicitly at semi-empirical quantitative evaluations on temperature-dependent isochoric lattice thermal capacity of several one-dimensional (linear), branched and ‘cyclic’ polymeric macromolecules, in order to replicate compellingly their experimentally obtained temperature-dependent isobaric counterparts. Those experimental dependencies might exhibit ‘sublinear’, nearly-linear, and ‘super-linear’ enlargement(s) with the temperature within ‘moderate’ temperature ranges alongside with so-called ‘low-temperature anomalies’, which are persistently manifested in profound decline(s) in the lattice thermal capacities with the temperature diminishment below the ‘moderate’ ranges. The obtained lengths of the spatial confinement of acoustic phonons located within the liner and branched polymers are compared with the Kuhn and persistent lengths of the linear, branched and cyclic polymers, while other simulation results are discussed in comparison with predictions of the ‘fractal theory’ of heat capacity of polymers, Tarasov’s equations, as well as with those of the ‘free energy of confinement’ approximation.