Toward Sulfur-Free RAFT Polymerization Induced Self-Assembly.

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Polymerization Induced Self-Assembly (PISA) is an emerging technique for creating colloidal structures.
• Methacrylate-based macromonomers are unexplored RAFT agents for PISA due to low reactivity.
• Heterogeneous polymerizations present challenges in controlling chain-growth and monomer partitioning.

Purpose of the Study:

• To explore the use of methacrylate-based macromonomers as RAFT agents in PISA.
• To address the obstacles of chain-growth control and monomer partitioning in PISA.
• To achieve controlled self-assembly of colloidal objects using PISA.

Main Methods:

• Investigated batch and semi-continuous dispersion polymerizations of hydroxypropyl methacrylate.
• Utilized poly(glycerol methacrylate) macromonomers as RAFT agents in aqueous media.
• Employed an amphiphilic thermoresponsive diblock copolymer to manage particle nucleation and monomer partitioning.
• Analyzed particle morphology using Transmission Electron Microscopy (TEM).

Main Results:

• Batch polymerizations showed limited control over chain-growth.
• Semi-continuous monomer feeding offered partial improvement in control.
• Employing a pre-phase-separated diblock copolymer successfully mitigated monomer partitioning.
• Successful PISA was achieved, yielding various particle morphologies.

Conclusions:

• Overcoming chain-growth and monomer partitioning is crucial for effective PISA.
• A strategy involving a pre-formed diblock copolymer enables controlled PISA with methacrylate macromonomers.
• This approach allows for the synthesis of diverse self-assembled colloidal structures.