Photo-induced bond breaking during phase separation kinetics of block copolymer melts: a dissipative particle dynamics study

Abstract

We studied phase separation kinetics of block copolymer melts while passing them through alternate photo-induced bond breaking (on) and recombination (off) reaction cycles, and discussed its effect on evolution morphologies, scaling functions, and length.

Purification of MDI Isomers Using Dynamic Falling Film Melt Crystallization: Experiment and Molecular Simulation

“…As shown in Figure 5 , the values in the dotted red line indicate g ( r ) = 1, and the arrow points to the position of g ( r ), where R is the average phase size. 38 − 40 …”

Phase separation kinetics of block copolymer melts confined under moving parallel walls: a DPD study

“…DPD is a powerful simulation technique to study the kinetic behavior of complex soft mesoscale systems. 16,[49][50][51] In DPD, a cluster of particles or molecules is modeled as a single bead, which makes DPD a more thriving numerical tool to simulate the system over a higher length and time scale than a traditional molecular dynamics (MD) simulation technique. [52][53][54] We integrate Newton's equation of motion for the system's time evolution:…”

“…49,50 The characteristic length and time scale in the actual units are estimated to be r c = 0.97nm and τ = 8.3ps, respectively. 16,17 We set the value of repulsive interaction strength a ij = 25 for the interaction between chemically compatible BCP beads (i.e., a AA = a BB = 25); this choice is made to reproduce the compressibility of water by coarse-graining ten water molecules into one bead. [49][50][51][52] The interaction parameter, a ij = 60 for chemically incompatible beads (i.e., a AB = 60).…”

“…The growth exponent varies as φ → 1/3, φ → 1, and φ → 2/3 for diffusive, viscous hydrodynamic, and inertial hydrodynamic regimes, respectively, in 3d. [12][13][14][15][16][17] Although many experimental studies verify the crossover from diffusive to viscous growth, the inertial hydrodynamic regime is still not observed experimentally. [18][19][20] However, a crossover from viscus to the inertial hydrodynamic regime has been reported recently for binary/ternary fluids in 3d, using the DPD simulation method, which is well-known for preserving the system's hydrodynamics.…”

“…[18][19][20] However, a crossover from viscus to the inertial hydrodynamic regime has been reported recently for binary/ternary fluids in 3d, using the DPD simulation method, which is well-known for preserving the system's hydrodynamics. 16,17 BCP melts coarsen into the well-ordered structures differently than macrophase separation of polymer blends. Numerous theoretical [1][2][3][4] and simulation 6,21 efforts have demonstrated that the variation of characteristic length scale with time initially follows a powerlaw with φ ∼ 1/4 in the weak-segregation 1 regime and φ ∼ 1/3 in the strong-segregation regime.…”