Analysis of the static properties of cluster formations in symmetric linear multiblock copolymers

Abstract

Abstract. We use molecular dynamics simulations to study the static properties of a single linear multiblock copolymer chain under poor solvent conditions varying the block length N , the number of blocks n, and the solvent quality by variation of the temperature T . We study the most symmetrical case, where the number of blocks of monomers of type A, n A , equals that of monomers B, n B (n A = n B = n/2), the length of all blocks is the same irrespective of their type, and potential parameters are also chosen symmetrically, as for a standard Lennard-Jones fluid. Under poor solvent conditions the chains collapse and blocks with monomers of the same type form clusters, which are phase separated from the clusters with monomers of the other type. We study the dependence of the size of the formed clusters on n, N and T . Furthermore, we discuss our results with respect to recent simulation data on the phase behaviour of such macromolecules, providing a complete picture for the cluster formations in single multiblock copolymer chains under poor solvent conditions.

A study for the static properties of symmetric linear multiblock copolymers under poor solvent conditions

“…the relative size and arrangement of the blocks [7]. The same has been shown to be true for a single multiblock copolymer chain under poor solvent conditions [13][14][15].…”

“…However, it has been shown that the different regimes of interest for the phase behavior can all be accessed by simulations [8-10, 13-15, 18]. Multiblock copolymers composed of two different types of blocks (A and B) alternating along the linear chain and length of a block A being equal to the length of block B that adopt coil-like structures in a good solvent or at temperatures close to the Θ [11][12][13][14][15]19] have been studied. The chemical difference of monomers should actually be kept responsible for an expansion in the chain dimensions with respect to the equivalent homopolymer chains (same total number of monomers) under the same thermodynamic conditions [11,12].…”

Collapse transitions in thermosensitive multi-block copolymers: A Monte Carlo study

“…Towards this end, computer simulations have recently made substantial strides 4,19,20,21,22,23,24,25,26,27,28,29,30,31 focusing on solutions of linear multiblock copolymers of the (A n B n ) m type, where n is the degree of polymerization of each block and m is the number of blocks. Systematic explorations within the large parameter space established quantitative relations on how copolymer architecture and intermolecular interactions determine the macroscopic phase behavior and the related chain conformations changes.…”

“…An extensive study on the phase behavior and the static properties of linear multiblock copolymers has been presented in a series of papers by Theodorakis, et al 22,23,24,25 Molecular Dynamics simulations of single linear multiblock copolymer chains were performed under various solvent conditions. In all cases, the A and B blocks were of equal length and with the same self-energetic interactions (i.e., common solvent conditions), whereas the unmixing tendency was introduced via A-B interactions.…”

“…Many of the simulation studies described above explored the effect of the block length on the phase behavior of multiblock copolymers; 4,19,21,24,30 however, they were limited to short lengths of the corresponding blocks and, in most cases, of the total chain length although a wide range of m-values has been explored. The results of our earlier study on the coil-to-globule transition of single homopolymer chains 33 had illustrated very clearly that there is a very strong dependence of the features of the transition and of the globule characteristics on the polymer molecular weight (MW).…”