Density functional theory for rod-coil polymers with different size segments.

Area of Science:

• Polymer physics
• Computational chemistry
• Materials science

Background:

• Rod-coil copolymers are complex macromolecules with diverse applications.
• Accurate theoretical models are needed to predict their behavior.
• Existing models may not fully capture segment size effects.

Purpose of the Study:

• To develop and validate a polymer density functional theory (PDFT) for rod-coil copolymers.
• To investigate the impact of segment size on local density and solvation forces.
• To provide a theoretical framework applicable to various polymer architectures.

Main Methods:

• Utilizing a modified fundamental measure theory for excluded-volume effects.
• Incorporating Wertheim's first-order thermodynamics perturbation theory for chain connectivity.
• Applying mean-field approximation for van der Waals attractions.
• Comparing PDFT predictions with simulation data for validation.

Main Results:

• The developed PDFT successfully reproduces simulation data for density profiles.
• Excluded volume effects of coil segments are critical for solvation force profiles in rod-coil brushes.
• Weak attraction near classical contact is observed due to vacuum effects.
• The theory accurately models copolymers with both different (A(5)D(3)) and same (A(5)B(3)) sized segments.

Conclusions:

• The proposed PDFT is a reliable tool for studying rod-coil copolymers.
• The findings offer insights into controlling surface and colloidal stabilization using rod-coils.
• The theoretical framework is adaptable to other polymer architectures with varying segment sizes.