Computer Simulation of Static and Dynamic Behavior of Diblock Copolymer Melts

Abstract

Monte Carlo simulations, using the cooperative motion algorithm (CMA), have been employed to investigate the statics and dynamics of both symmetric and asymmetric diblock copolymer melts near the order-disorder transition. Investigation of the static properties has revealed the existence of two characteristic temperatures in the system: the ODT expressed as a peak in the heat capacity and a higher temperature T1 at the crossover between the homogeneous state and the state with considerably increased concentration fluctuations. As T1 is crossed, the increased amplitude of concentration fluctuations is accompanied by a significant increase of the average end-to-end distance of chains and the local chain orientation correlation. The dynamic properties of these systems have been observed by means of the relaxation of the single-bond, the chain end-to-end vector, and the block end-to-end vector, as well as by the single point concentration autocorrelation function. Corresponding relaxation times have been determined as a function of temperature. Below the ODT, a splitting of both the chain and the block end-to-end vector orientation correlation function is observed, while the relaxation of composition fluctuations becomes slower than that of the block orientation. The slow process is attributed to the conformal relaxation of the coherent interfaces formed in the ordered state.

Interface Orientation and Chain Conformation in Simulated Symmetric Diblock Copolymer Lamellar Systems

“…Figure 1 shows an example of variation of the average interaction energy and the specific heat with temperature for a symmetric diblock copolymer system studied previously. [6] The dependencies allow one to infer that the microphase separation temperature T MS is nearly proportional to N, which justifies the use of the T/N scale. [6,7] According to the simulation results, this temperature separates the strong and weak segregation regimes observed below and above T MS , respectively.…”

“…Both experimental [1][2][3][4][5] and computer simulation [6][7][8][9][10] methods have been applied to analyze composition profiles in copolymers of immiscible blocks undergoing microphase separation to the characteristic morphologies: spherical, cylindrical, or lamellar, in accordance with their composition. Most of the attention has been directed towards the simplest lamellar morphologies for which information at the molecular level was obtained by means of X-ray and Summary: We describe the results of Monte Carlo simulations, based on the cooperative motion algorithm, of the lamellar structure generated at finite temperature by a symmetric diblock copolymer.…”

“…Computer simulations of the microphase separated copolymer states offer the possibility to obtain even more details about the interfacial structures. [6][7][8][9][10][11] This information includes: descriptions of chain deformation, orientation correlations, chain end distributions, and concentration profiles at the interfaces of the simulated diblock copolymer systems.…”

“…[12,13] Proper interpretation of these experimental data depends on knowledge about the orientation of copolymer chains at the interface and the distribution of junction points between the blocks within the interface. The simulation method used here is the cooperative motion algorithm (CMA), [6,7] which has already been successfully applied for simulation of diblock copolymer melts under various conditions ranging between the homogeneous and the strong segregation limits.…”

Protein‐like behavior of multiblock copolymer chains in a selective solvent by a variety of lattice and off‐lattice Monte Carlo simulations

“…Therefore, in our previous work [11], we performed a lattice Monte Carlo (MC) simulation of single alternating multiblock copolymer chains in a selective solvent, 4 (A B) A, -/ using Cooperative Motion Algorithm (CMA) [12,13], in order to investigate the properties of such chains upon cooling. The selectivity of the solvent implies that the interaction energy between solvent and one type of chain segments is different from the interaction energy between solvent and another type of chain segments.…”