Shaping Block Copolymer Microparticles by Positively Charged Polymeric Nanoparticles.

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Block copolymer (BCP) microparticles are crucial in nanotechnology and biomedicine.
• Precise control over BCP microparticle shape and structure is essential for their performance.
• Existing methods for shape control require further refinement for diverse applications.

Purpose of the Study:

• To develop a novel method for precisely regulating the shape and structure of polystyrene-b-polydimethoxysiloxane (PS-b-PDMS) microparticles.
• To investigate the role of electrostatic interactions in dictating BCP microparticle morphology.
• To establish a facile strategy for tailoring BCP morphologies.

Main Methods:

• Utilizing positively charged core-crosslinked nanoparticles (CNPs) as a cosurfactant with cetyltrimethylammonium bromide (CTAB).
• Investigating the influence of electrostatic repulsive interactions between CNPs and CTAB on PS-b-PDMS particle shape.
• Introducing sodium chloride (NaCl) to modulate electrostatic repulsion and induce shape transformation.

Main Results:

• PS-b-PDMS microparticles transform from striped Janus ellipsoids to onion-like microspheres at a critical NaCl concentration (c_NaCl).
• The critical NaCl concentration required for shape transformation is dependent on the crosslinking degree of the CNPs.
• A correlation between CNP crosslinking degree and the critical NaCl concentration was observed, showing an initial increase followed by a plateau.

Conclusions:

• A simple and effective strategy for tailoring BCP microparticle morphology has been demonstrated.
• Electrostatic interactions, modulated by CNPs, CTAB, and NaCl, are key to controlling BCP shape.
• This approach offers a versatile platform for designing advanced BCP-based nanomaterials.