Synthesis of Amphiphilic Block Copolymer and Its Application in Pigment-Based Ink

Area of Science:

• Polymer Chemistry
• Materials Science
• Surface Chemistry

Background:

• Amphiphilic block copolymers are crucial for aqueous color inks in visual communication.
• Conventional synthesis methods are complex, low-yield, and environmentally costly.
• Need for efficient and sustainable dispersant synthesis for water-based inks.

Purpose of the Study:

• To develop a novel, facile, and efficient method for synthesizing amphiphilic AB di-block copolymers.
• To evaluate the effectiveness of the synthesized polycaprolactone-block-polyacrylic acid (PCL-b-PAA) as a dispersant for water-based color inks.
• To characterize the properties of the PCL-b-PAA copolymer and the resulting dye dispersion.

Main Methods:

• Simultaneous cationic ring-opening polymerization (ROP) of ε-caprolactone and reversible addition-fragmentation chain-transfer (RAFT) polymerization of acrylic acid.
• Characterization of the PCL-b-PAA copolymer, including molecular weight and surface excess (Γmax).
• Evaluation of micelle formation (critical micelle concentration [CMC] and dimension) and ink dispersion properties (viscosity, particle size, stability).

Main Results:

• Successfully synthesized PCL-b-PAA with a molecular weight of 1400 g/mol, consistent with theoretical values.
• Demonstrated high surface excess (Γmax) and stable micelle formation (30 nm) at low concentrations (CMC = 10⁻⁴ wt%).
• Prepared a model ink dispersion with near-Newtonian behavior, low viscosity, unimodal particle size (approx. 500 nm), and excellent stability, even after thermal aging.

Conclusions:

• The novel combined polymerization strategy offers an efficient and sustainable route to amphiphilic block copolymers.
• PCL-b-PAA serves as an effective polymeric dispersant for dye dispersions, yielding stable, low-viscosity inks.
• The developed dispersants and ink formulations are highly suitable for visual communication design and printing applications.