Mechanisms of Nucleation and Solid–Solid-Phase Transitions in Triblock Janus Assemblies

Abstract

A model, including the chemical details of core nanoparticles as well as explicit surface charges and hydrophobic patches, of triblock Janus particles is employed to simulate nucleation and solid–solid phase transitions in two-dimensional layers. An explicit solvent and a substrate are included in the model, and hydrodynamic and many-body interactions were taken into account within many-body dissipative particle dynamics simulation. In order not to impose a mechanism a priori, we performed free (unbiased) simulations, leaving the system the freedom to choose its own pathways. In agreement with the experiment and previous biased simulations, a two-step mechanism for the nucleation of a kagome lattice from solution was detected. However, a distinct feature of the present unbiased versus biased simulations is that multiple nuclei emerge from the solution; upon their growth, the aligned and misaligned facets at the grain boundaries are introduced into the system. The liquid-like particles trapped between the neighboring nuclei connect them together. A mismatch in the symmetry planes of neighboring nuclei hinders the growth of less stable (smaller) nuclei. Unification of such nuclei at the grain boundaries of misaligned facets obeys a two-step mechanism: melting of the smaller nuclei, followed by subsequent nucleation of liquid-like particles at the interface of bigger neighboring nuclei. Besides, multiple postcritical nuclei are formed in the simulation box; the growth of some of which stops due to introduction of a strain in the system. Such an incomplete nucleation/growth mechanism is in complete agreement with the recent experiments. The solid–solid (hexagonal-to-kagome) phase transition, at weak superheatings, obeys a two-step mechanism: a slower step (formation of a liquid droplet), followed by a faster step (nucleation of kagome from the liquid droplet).

Optimization of the Warpage of Fused Deposition Modeling Parts Using Finite Element Method

“…It is reported that decreased coating weight generates higher hydrophobicity and surface roughness while thick layers come with fewer empty spaces between the layers, resulting in a reduced hydrophobic effect. In addition, thin layers of filament are most likely to retain the intrinsic unevenness of the surface [34,35]. From Table 5, the predictions of the finite element method were found to be close to the experimental results in some simulations but diverged in others.…”

“…It is reported that decreased coating weight generates higher hydrophobicity and surface roughness while thick layers come with fewer empty spaces between the layers, resulting in a reduced hydrophobic effect. In addition, thin layers of filament are most likely to retain the intrinsic unevenness of the surface [34,35]. Some studies reported on the extensive hydrophobic nature of thin coating related to the higher roughness [36], while other studies [37] suggested decreased surface roughness as well as hydrophobicity due to filled up voids and formation of large aggregate in the case of multiple layers.…”

DPD Study on the Interfacial Properties of PEO/PEO-PPO-PEO/PPO Ternary Blends: Effects of Pluronic Structure and Concentration

“…As illustrated by the previous studies, the exact equilibrium location of phase boundaries in the phase separation can be precisely determined by adding a bias to the potential energy of the system to sample different configurations or choosing larger repulsion parameters for the different types of beads to lower the free energy barrier. [ 43 , 44 ] In this work, we mainly focus on the interfacial thermodynamic properties, and it should be noted that the phase transition points (such as the temperature, pressure, and copolymer concentration) are not the exact equilibrium transition conditionist. To save the computational cost and speed up the formation of the interfaces, the PEO, PPO homopolymers, and PEO-PPO-PEO triblock copolymers were initially placed in distinct locations along the x-direction in the box, which can greatly enhance computing efficiency.…”

Synthesis of Amorphous Conjugated Copolymers Based on Dithienosilole-Benzothiadiazole Dicarboxylic Imide with Tuned Optical Band Gaps and High Thermal Stability

“…Compared to the E g of PDTSDTTAZ, PDTSTAZ and PDTSNTDO (1.81, 1.78 and 1.65 eV, respectively), both polymers had a significantly lower E g . The significant lowering of band gaps is thought to be a result of adopting a 2D (thin film) structure since the band gap is known to be low in symmetric 2D soft matter systems [50]. As a result, this new type of polymer adopted more planar structures with a greater intrachain charge transfer alongside the polymer backbone.…”