Computation simulation of polyolefins and Monte Carlo simulation of RIS chains on a high-coordination diamond lattice

Computer simulation of polymeric systems were performed using two different modeling approaches: Fully atomistic and coarse-grained modeling. They were compared on the basis of their advantages and their drawbacks. The results were compared to experimental findings to test the validity of the simulation methodology.; Fully atomistic modeling via Molecular Dynamics was used to study the surface and interfacial properties of polyolefins in order to understand the origins of the anomalous mixing behaviour in the blends of PIB/hhPP and PIB/P78. Good quantitative agreement was obtained between simulations and experiments in the values of the surface tensions in erg.cm−2 ($gPIBsim$ = 34.3 ± 6.1 and $ghhPPsim$ = 29.7 ± 10.9 vs. $gPIBexp$ = 33.6 and $ghhPPexp$ = 30.1). The interfacial tensions were calculated as −24.87 for PIB/hhPP and −9.44 for PIB/P78 in erg.cm−2 indicating a stronger attraction between components in PIB/hhPP than in PIB/P78. The large negative value of the interfacial tension in PIB/hhPP was constituted primarily from the local intramolecular energy contribution (−55.42 erg.cm−2). This result supports the idea of packing contributions to anomalous mixing behaviour that is expected to lead to a broader distribution of local chain conformations in a mixture environment mainly dominated by the intramolecular energetics.; Coarse-grained modeling via Monte Carlo simulation on the 2nnd lattice was used to study the mixing behaviour of PE with hhPP in the melt state. The demixing nature of the polymer blend previously determined by experiments was recovered through the structural (e.g., pair correlation functions) and energetic (e.g., interaction parameter) properties. A quantitative disagreement exists between simulations and experiments in the difference of the Flory-Huggins interaction parameters, (χ_sim = 0.01) vs. (χ_exp = 0.09) both at 473 K. A plausible explanation of the high value of χ is the overestimation of the demixing (inhomogeneous) nature of the mixture arising from the incorporation of fewer number of shells in the determination of the long-range interactions, since eliminating higher number of shells is expected to increase the inhomogeneity while the incorporation of infinite number of shells would ideally simulate the homogeneous nature of the mixtures.