Oriented primary crystal nucleation in lamellar diblock copolymer systems

Area of Science:

• Polymer Science
• Materials Science
• Crystallography

Background:

• Diblock copolymers form ordered lamellar structures.
• Controlling crystal orientation in block copolymers is crucial for material properties.
• The nucleation and growth of crystals within these structures are complex.

Purpose of the Study:

• To investigate the primary crystal nucleation of diblock copolymers in a lamellar phase using numerical simulations.
• To understand the influence of polymer block connectivity on crystal orientation.
• To elucidate the molecular origins of competing crystallite orientations.

Main Methods:

• Numerical simulation of crystal nucleation in diblock copolymers.
• Modeling of lamellar phase structures with one crystallizable and one glassy block.
• Analysis of crystallite orientation relative to the lamellar plane under different conditions.

Main Results:

• Crystals in intact diblock copolymers nucleate with their chain axis perpendicular to the lamellar plane.
• In systems with broken block junctions, crystallites align parallel to the lamellar plane.
• The connectivity between polymer blocks significantly influences crystal orientation.

Conclusions:

• The study clarifies the molecular mechanisms governing crystal orientation in block copolymers.
• Findings explain the observed competition between parallel and perpendicular crystallite alignments in real systems.
• This research provides insights for designing block copolymer materials with desired crystalline structures.