Combining photocontrolled-cationic and anionic-group-transfer polymerizations using a universal mediator: enabling...

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Synthesizing diverse block copolymers from multiple polymerization mechanisms and monomer classes remains a significant challenge in polymer chemistry.
• Universal mediators are crucial for creating complex polymer architectures without requiring intermediate compatibilization steps.
• While thiocarbonyl thio (TCT) groups mediate radical polymerization with cationic or anionic polymerization, a sequential cationic-anionic system has not been previously reported.

Purpose of the Study:

• To develop a novel thiocarbonyl thio (TCT) universal mediator system capable of sequential photocontrolled cationic polymerization and thioacyl anionic group transfer polymerization.
• To synthesize poly(ethyl vinyl ether)-block-poly(thiirane) block copolymers for the first time.
• To demonstrate the potential of this system for creating complex terpolymers by incorporating a third monomer class via radical polymerization.

Main Methods:

• Utilized a TCT universal mediator to sequentially initiate photocontrolled cationic polymerization of ethyl vinyl ether.
• Followed by thioacyl anionic group transfer polymerization of thiirane.
• Chain-extended the resulting diblock copolymer using radical polymerization of N-isopropylacrylamide.

Main Results:

• Successfully synthesized poly(ethyl vinyl ether)-block-poly(thiirane) block copolymers, representing the first instance of such a structure.
• Thermal analyses confirmed microphase separation in the synthesized block copolymers.
• Achieved the first example of a triblock terpolymer synthesized from three different monomer classes via three distinct polymerization mechanisms without end-group modification.

Conclusions:

• The developed TCT universal mediator system enables facile and sequential access to cationic-anionic block copolymers.
• This approach overcomes limitations in synthesizing complex polymer architectures, offering new possibilities for materials design.
• The system's compatibility with radical polymerization allows for the creation of advanced multi-block copolymers with diverse functionalities.