Influence of Strong Electron-Donor Monomers in Sequence-Controlled Polymerizations

Area of Science:

• Polymer Chemistry
• Organic Synthesis
• Materials Science

Background:

• Controlled radical polymerization techniques are crucial for synthesizing polymers with defined architectures.
• Sequence control in copolymerization allows for fine-tuning of material properties.
• Styrenic monomers with electron-donating groups can influence polymerization kinetics and copolymer microstructure.

Purpose of the Study:

• To investigate the effect of donor substituents on styrenic monomers in sequence-controlled radical copolymerization.
• To synthesize well-defined copolymers using nitroxide-mediated polymerization (NMP).
• To explore the hydrolysis of resulting copolymers and assess the stability of their sequence-controlled microstructure.

Main Methods:

• Nitroxide-mediated polymerization (NMP) using BlocBuilder MA.
• Copolymerization of donor-substituted styrenes (4-methylstyrene, 4-acetoxystyrene, 4-tert-butoxystyrene) with N-substituted maleimides.
• Characterization of copolymer molecular weights, molecular weight distributions, and microstructures.
• Hydrolysis of ester and Boc-protected amine functionalities in the copolymers.

Main Results:

• NMP enabled the synthesis of copolymers with controlled molecular weights and narrow molecular weight distributions.
• Donor substituents on styrenic monomers significantly improved the precision of sequence control in copolymerization.
• 4-tert-butoxystyrene demonstrated the most favorable donor/acceptor copolymerization behavior.
• Sequence-controlled microstructures were successfully obtained with various functional N-substituted maleimides.
• Hydrolysis of the copolymers preserved the sequence-controlled microstructure.

Conclusions:

• Donor-substituted styrenic monomers are beneficial for achieving high sequence control in NMP with maleimides.
• The developed method allows for the synthesis of functional copolymers with precisely controlled sequences.
• The sequence-controlled architecture is robust and stable under hydrolysis conditions, enabling access to new poly(hydroxystyrene) derivatives.