Synthesis of Poly(methacrylic acid)-block-Polystyrene Diblock Copolymers at High Solid Contents via RAFT Emulsion Polymerization.

Iklima Oral,Volker Abetz,Larissa Grossmann,Elena Fedorenko,Jana Struck

doi:10.3390/polym13213675

Abstract

The combination of polymerization–induced self-assembly (PISA) and reversible–addition fragmentation chain transfer (RAFT) emulsion polymerization offers a powerful technique to synthesize diblock copolymers and polymeric nanoparticles in a controlled manner. The RAFT emulsion diblock copolymerization of styrene and methacrylic acid (MAA) by using a trithiocarbonate as surfactant and RAFT agent was investigated. The Z-group of the RAFT agent was modified with a propyl-, butyl- and dodecyl- sidechain, increasing the hydrophobicity of the RAFT agent to offer well-controlled polymerization of poly(methacrylic acid)-block-polystyrene (PMAA-b-PS) diblock copolymers at high solid contents between 30–50 wt% in water. The kinetic data of the PMAA homopolymerization with the three different RAFT agents for various solvents was investigated as well as the RAFT emulsion polymerization of the diblock copolymers in pure water. While the polymerization of PMAA-b-PS with a propyl terminus as a Z-group suffered from slow polymerization rates at solid contents above 30 wt%, the polymerization with a dodecyl sidechain as a Z-group led to full conversion within 2 h, narrow molar mass distributions and all that at a remarkable solid content of up to 50 wt%.

Highlights

Published: 25 October 2021The advent of controlled radical polymerization (CRP) gave rise to a wide variety of well-defined homopolymers and copolymers [1,2,3,4]
The synthesis of PMAA-b-PS diblock polymers was performed according to the previous work of Chaduc et al where the CTA1 was used and different pH-values, solvents, concentrations and reaction times were studied [34]
A carboxylic acid group was chosen as the R group of the reversible–addition fragmentation chain transfer (RAFT) agent, since it is similar to the structure of methacrylic acid (MAA), which will be polymerized as the hydrophilic block

Summary

Introduction

Published: 25 October 2021The advent of controlled radical polymerization (CRP) gave rise to a wide variety of well-defined homopolymers and copolymers [1,2,3,4]. RAFT polymerization can be conducted in a range of solvents [6], including protic solvents such as water [7,8] and lower alcohols such as methanol [9] and ethanol [10], non-polar solvents, e.g., n-alkanes [6] and more exotic media such as ionic liquids [9,11]. It can be performed in bulk, solution or dispersion (with emulsion being a subclass of it) [12,13,14].

Methods

Results

Conclusion