Polymers for Photothermography:  Controlled Thermal Release of Color Photographic Developer from Substituted Polystyrene Derivatives

• Published in: Macromolecules 2006-08, Vol.39 (17), p.5686-5695
• Main Authors: Robello, Douglas R, Levy, David H, Reynolds, James H, Southby, David T, Twist, Stephen L
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma060352b

A series of functionalized styrenic polymers were synthesized that were designed to release a low molar mass compound, a color photographic developer (a substituted phenylenediamine), when heated. The developer moieties were covalently bound via special protecting groups (“switches”) that were stable at ambient temperature but decomposed to release the developer above 100 °C. In one series, the protecting group consisted of benzylic carbamates, designed to release via a cationic mechanism. In a second series, the protecting groups comprised ethylene linkages set up for 1,2-elimination, and release occurred via an anionic mechanism. Waterborne formulations of the title polymers suitable for coating were prepared via milling, evaporative dispersion, or emulsion polymerization. The polymers were incorporated into silver halide-based photothermographic media, which were capable of forming color images after appropriate exposure and heat treatment, indicating successful controlled release of the developer. This system may be applicable to other controlled-release applications in which a bound compound is to be released when the material is heated.