How soft is too soft? Tuning order and disorder in dimeric core-soft colloids with bond flexibility.

Area of Science:

• Soft Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Phase transitions in soft-matter systems are crucial for material properties.
• Understanding the role of internal structure, like dimer flexibility, is key to controlling these transitions.

Purpose of the Study:

• To investigate how the internal flexibility of dimers affects phase transitions.
• To explore the relationship between dimer rigidity and the formation of crystalline and amorphous phases.

Main Methods:

• Molecular dynamics simulations were used to model soft-matter systems of dimers.
• The stiffness of the harmonic springs connecting monomers was varied to control dimer rigidity.

Main Results:

• Flexible dimers exhibited behavior similar to monomers, forming body-centered cubic (BCC) and hexagonal close-packed (HCP) phases.
• Increasing dimer rigidity led to a coexistence region between BCC and HCP phases.
• Rigid dimers resulted in expanded amorphous regions and incomplete crystallization, forming mixed phases due to geometric frustration.

Conclusions:

• Dimer flexibility is a critical parameter controlling structural organization in soft-matter systems.
• Geometric frustration in rigid dimers hinders optimal packing, promoting amorphization.
• Findings offer insights for designing tunable soft materials with controlled phase behavior.