Chain Transfer Kinetics of Rhodixan^® A1 RAFT/MADIX Agent

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Industrial-scale production of block copolymer additives is crucial for aqueous formulations.
• Reversible-Deactivation Radical Polymerization (RDRP) techniques, including RAFT/MADIX, offer control over polymer architecture.
• Rhodixan® A1 (O-ethyl S-(1-methoxycarbonylethyl)dithiocarbonate) is a key RAFT/MADIX agent.

Purpose of the Study:

• To evaluate the effectiveness of Rhodixan® A1 in producing block copolymer additives.
• To determine chain transfer coefficients for Rhodixan® A1 with various monomer classes.
• To assess the control over polymer molecular weight and dispersity.

Main Methods:

• Utilized 25 different styrenic, acrylate, and acrylamide monomers.
• Experimentally determined chain transfer coefficients (C_tr) and interchain transfer coefficients (C_tr,PnXA1).
• Analyzed polymer molecular weight and dispersity at high monomer conversion.

Main Results:

• Chain transfer coefficients to Rhodixan® A1 were low, ranging from 0.6 to 3.8.
• Transfer coefficients followed the order: styrenics < acrylates < acrylamides.
• Polymers with predetermined molecular weights were obtained with dispersities inversely proportional to C_tr,PnXA1.

Conclusions:

• Rhodixan® A1 facilitates the industrial-scale synthesis of block copolymers with controlled molecular weights.
• The RAFT/MADIX technique using Rhodixan® A1 is versatile for creating complex copolymers from monomers with differing reactivities.
• This agent is effective for both conjugated and unconjugated monomers, expanding its applicability.