ABSTRACT
We study the macroscopic behavior of a pyramid-like nano-construct made of linear macromolecular chains. The average mean square end-to-end distances of the six edges of the pyramoid are evaluated by means of the Gaussian chain model and are found smaller than those of free chains because of architecture confinement. We also evaluate the average areas of the four faces which give a first estimate of the open windows towards the interior space of the macromolecular construct and its loading capacity. The average volume of the polymeric nano-container, which provides a measure of its interior emptiness and carrying ability, is estimated as well. The density of monomers at each point of the construct shows the three-dimensional character of the nano-cage and the location of its entrances and voids.
ABSTRACT
The authors present a detailed study of the microscopic parameters, which control the miscibility in binary linear/star polymer blends. The effective interactions of linear/star polymer blends are studied by means of Monte Carlo simulations and comparison is made with linear/linear and star/star blends, which they also determined. Using the bond fluctuation model on a simple cubic lattice, the authors are able to simulate symmetric linear/linear, star/star, and, for the first time, linear/star blends with a moderate number of arms. The simulations were performed at a volume fraction of occupied lattice sites phi=0.5, which corresponds to dense polymer mixtures for this algorithm. In particular, we study star/star blends with 4, 8, and 12 arms and the respective linear/linear blends as well as linear/star blends, all having the same total number of units equal to 73 and 121. The authors find that linear/star blends are more miscible than the corresponding linear/linear blends, which is in agreement with recent experimental and theoretical results. They find that linear/star mixtures are less miscible than star/star blends, a result which is also verified by theoretical findings.
ABSTRACT
Conformational properties of a dendritic block copolymer of the first generation are studied by means of an analytic calculation and dimensionality techniques. The polymer can have different functionalities and branch lengths in the interior region and the exterior shell. Three parameters are included in order to describe the intensity of the interactions between the same or different monomeric units. Based on the average end to end distances of the branches effective angles are defined in order to study how the microscopic parameters control the position and activity of the end groups, but also the hollowness in the internal region and the tweezing ability of the external shell of the macromolecule.
