Well-shaped poly(dimethylsiloxane)-based copolymer nanowires from spherical micelles via kinetic shape evolution

Area of Science:

• Polymer Science
• Materials Science
• Nanotechnology

Background:

• Copolymers are of significant interest for creating self-assembled nanostructures.
• Kinetic control offers a promising route for directed self-assembly of advanced materials.

Purpose of the Study:

• To develop a kinetic approach for synthesizing self-assembled nanowires using a novel PDMS-based block copolymer.
• To investigate the self-assembly mechanism and the influence of solvent properties on nanostructure formation.
• To stabilize the formed nanowires through UV-induced cross-linking.

Main Methods:

• Synthesis of poly(dimethylsiloxane)-block-poly[2-(cinnamoyloxy)ethyl methacrylate] (PDMS-b-PCEMA) via ATRP and subsequent functionalization.
• Observation of self-assembly kinetics and shape evolution in various solvents (THF, DCM, acetone).
• Characterization of nanostructures (micelles, nanowires) and their dimensions (25-35 nm diameter).
• UV-induced cross-linking of PCEMA segments to enhance nanowire stability.

Main Results:

• PDMS-b-PCEMA copolymers self-assemble into core-shell spherical micelles in THF, which kinetically transform into nanowires over 5 days.
• Nanowire formation is dependent on solvent permittivity, with nanowires forming in THF and DCM, and micelles in acetone.
• The PDMS component facilitates shape transformation, while PCEMA controls diameter; nanowires exhibit a PCEMA inner core and PDMS shell.
• UV irradiation successfully cross-links the PCEMA groups, stabilizing the nanowire structure.

Conclusions:

• A novel kinetic strategy for the formation of stable polymer nanowires has been established.
• The study highlights the critical role of solvent properties and copolymer composition in directing self-assembly pathways.
• This work provides valuable insights for designing and fabricating diverse copolymer-based nanostructures.