Brownian Molecular Dynamics Simulation on Self-Assembly Behavior of Rod−Coil Diblock Copolymers

Abstract

Brownian molecular dynamics simulations are carried out on the self-assembly behavior of rod−coil diblock copolymers. The copolymer molecule is represented by a linear chain consisting of definite beads connecting by harmonic bond stretching potential. The rigidity of the rod block is introduced by harmonic potential for bend at a substantially zero bond angle. The micelle structures formed by such copolymers and molecular packing of rod blocks are investigated. Transitions of aggregate structure are found with changing Lennard-Jones (LJ) interaction εRR of rod pairs. The rod blocks tend to align orientationally and pack hexagonally in the core to form a smectic-like disk structure at the higher εRR. With decreasing εRR, a disk micelle is gradually changed to a new string structure, where the twisting of rod blocks packing in the core has been discovered and further breaks into some small aggregates until unimers. The radius of gyration and order parameter of rod blocks are calculated to confirm such a transition from disk to string structure. The regions of thermodynamic stability of disk, string, and small aggregates are constructed in the diagrams of block chain length against εRR and temperature vs εRR. Increase of the rod block length leads to a more dramatic decrease of the critical micelle interaction (CMI) than decrease of the coil block length does. The onsets of string and disk formation move to higher εRR with decreasing rod block length and/or increasing coil length. Meanwhile, the regions of string micelle and small aggregates become wider. Some simulation results are in agreement with existing experimental observations and theoretical predictions.

Drug releasing behavior of hybrid micelles containing polypeptide triblock copolymer

“…In addition to the experimental studies, we also performed molecular dynamics (MD) simulations using a Brownian dynamics to further verify the structures. The MD simulations offered a microscopic understanding of the thermodynamic properties and a detailed picture of the self-assembled aggregates [41][42][43][44][45]. Following the micelle characterization, we studied their behavior as drug carriers.…”

Self-assembly of rod-coil-rod triblock copolymers: A route toward hierarchical liquid crystalline structures

“…The reduced temperature T can be converted into the real unit through the relation of 1T = ε/R = 60.1 K, where the energy unit ε is chosen as 0.5 kJ/mol, and R is the gas constant. 46 Therefore, as the reduced temperature changes from 6.0 to 1.0, the actual temperature decreases from 360.6 K to 60.1 K.…”

“…The BD simulations can be used to investigate the self-assembly of the M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 rod-coil-rod copolymers due to their success in studying the phase behavior of the copolymers with rod blocks. [29][30][31][46][47][48] For example, Glotzer et al performed BD simulations on rod-coil diblock copolymers, and obtained various LC phases, including cubic phase, smectic C phase, tetragonally perforated lamellar phase, and honeycomb phase. 31 The morphologies of LC structures were found to be dependent of rod aspect ratio, coil length, and temperature.…”

Dissipative Particle Dynamics Simulation on Self-Assembly of Comb-Coil Copolymers

“…为了进一步理解和掌握梳 状-线性共聚物的自组装行为, 本文将采用上述方法, 模拟梳状-线性共聚物在选择性溶剂中的自组装行为, 并探讨侧链长度和侧链数量等因素对聚集体结构的影 响. [19,20] , 而 低曲率的盘状胶束(或囊泡)的形成可以保证梳状亚结构 在聚集体核内的紧密堆积 [36] . 与第 II 类聚集体相比, 第 I 类聚集体的形貌较为丰富.…”